Dissertations / Theses: 'Hyperfine transitions'

1

Correge, G. "Calculation of fine and hyperfine transitions in atoms and ions." Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394582.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Döringshoff, Klaus. "Optical frequency references based on hyperfine transitions in molecular iodine." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19156.

Full text

Abstract:

Diese Arbeit beschäftigt sich mit der Entwicklung und Untersuchung von optischen Absolutfrequenzreferenzen basierend auf rovibronischen Übergängen in molekularen Jod. Dabei werden Methoden der Doppler-freien Sättigungsspektroskopie angewendet, um einzelne Übergänge der Hyperfeinstruktur mit Linienbreiten unterhalb von 1 MHz im B-X System von molekularem Iod bei 532 nm, der zweiten harmonischen des Nd:YAG-Laser, aufzulösen. Elektronische Regelungstechniken ermöglichen eine präzise Stabilisierung der optischen Frequenz auf die Linienmitte der Übergänge mit einer Auflösung von Teilen in 10^5. Mit dem Ziel einer weltraumtauglichen Absolutfrequenzreferenz für zukünftige Weltraummissionen, wurden zwei Spektroskopiemodule konzipiert und in quasi-monolithischen Glaskeramik-Aufbauten, als sogenanntes elegant breadboard model und engineering model, realisiert. Diese Jodfrequenzreferenzen wurden im Detail in Bezug auf ihre Frequenzstabilität und Reproduzierbarkeit untersucht und Letzteres wurde für die angestrebte Weltraumqualifizierung ersten Umwelttests, sowohl vibrations- als auch thermischen Belastungstests, unterzogen. Für die Untersuchung der Frequenzstabilität dieser Jodreferenzen wurde ein auf einen optischen Resonator hoher Güte stabilisiertes Lasersystem für direkte Frequenzvergleiche bei 1064 nm realisiert. Die Analyse der Frequenzstabilität der Jod Referenzen zeigt eine Frequenzstabilität von 6x10^−15 bei 1 s, und weniger als 2x10^−15 bei 100 s Integrationszeit, was der bis heute besten veröffentlichten Frequenzstabilität entspricht die mit Jod Referenzen erreicht wurde. Mit der erreichten Frequenzstabilität ermöglichen diese Absolutfrequenzreferenzen präzise Lasersysteme für zukünftige Weltraummissionen wie z.B. zur Detektion von Gravitationswellen, zur Vermessung des Gravitationsfelds der Erde oder für Präzisionstest fundamentaler Theorien der Physik.
This thesis deals with the development and investigation of optical absolute frequency references based on rovibronic transitions in molecular iodine. Doppler-free saturation spectroscopy methods are employed to resolve individual transitions of the hyperfine structure with linewidths below 1 MHz in the B-X system of molecular iodine at 532 nm with the second harmonic of Nd:YAG lasers. Electronic feedback control systems are employed for laser frequency stabilization to the line center of the optical transitions with a line splitting of 10^5. With the goal of a space qualified optical absolute frequency reference for future laser-interferometric space missions, two spectroscopy setups were designed and realized in quasi-monolithic, glass-ceramic setups as so called elegant bread board model and engineering model. These iodine references were characterized in detail with respect to their frequency stability and reproducibility and the engineering model was subject to environmental tests, including vibrations and thermal cycling to verify its applicability in future space missions. For the investigation of the frequency instability of these iodine references, a frequency stabilized laser system was realized based on a temperature controlled high Finesse ULE cavity for direct frequency comparisons at 1064 nm. Analysis of the frequency stability of the iodine references revealed exceptionally low fractional frequency instability of 6x10^−15 at 1 s, averaging down to less than 2×10^−15 at 100 s integration time, constituting the best reported stability achieved with iodine references to date. With the demonstrated performance, these absolute frequency references enable precision laser systems required for future space missions that are dedicated to, e.g., the detection of gravitational waves, mapping of the Earth’s gravitational field or precision test of fundamental physics.

APA, Harvard, Vancouver, ISO, and other styles

3

Razet, Annick. "Transitions hyperfines de l'iode moléculaire au service de la métrologie des fréquences optiques." Paris 11, 1988. http://www.theses.fr/1988PA112014.

Full text

Abstract:

Calculs théoriques sur les structures fines et hyperfines, lisses à partir de mesures expérimentales faites aux environs de raies émises par des lasers à argon et à hélium-neon, et estimations théoriques concernant diverses transitions hyperfines obtenues à l'aide d'un laser à colorant continument accordable
Le développement, depuis maintenant presque vingt ans, des sources lasers stabilisées, a donné un regain d'intérêt aux applications métrologiques concernant les références de fréquences ou de longueurs. Parmi tous ces lasers fonctionnant dans des intervalles spectraux différents, ceux émettant dans le visible présentent un intérêt tout particulier pour ce type d'applications. La plupart sont stabilisés sur une composante hyperfine d’une raie donnée de la molécule d’iode (dont le spectre d’absorption couvre une grande partie du spectre visible) par des techniques d’absorption saturée soit dans une cellule (placée à l’intérieur ou à l’extérieur de la cavité laser) soit en utilisant un jet moléculaire. Le choix d’une raie particulière et d’une composante hyperfine particulière dépend non seulement des caractéristiques métrologiques de cette raie (pureté, largeur, …) mais aussi des sources lasers utilisées pour ces applications. L'étude théorique de ce spectre très riche est d'une grande importance pour faire un tel choix et pour apprécier les limites fondamentales des caractéristiques métrologiques d'une raie donnée. Pour cela, des calculs informatiques concernant les structures fines et hyperfines, les largeurs de transitions hyperfines, etc… sont nécessaires. Quelques exemples pratiques sont étudiés, nous présentons des calculs théoriques lissés à partir de mesures expérimentales faites aux environs de raies émises par des lasers à argon et à hélium-néon, ainsi que des estimations théoriques concernant diverses transitions hyperfines obtenues à l'aide d'un laser à colorant continûment accordable. Ces diverses sources lumineuses ont été utilisées pour faire des mesures de rapport de longueurs d'onde ou de fréquences à partir d'un interféromètre de type Michelson à champ compensé à différence de marche fixe. Les résultats obtenus ont une incertitude relative de l'ordre de dix puissance moins dix

APA, Harvard, Vancouver, ISO, and other styles

4

Cox, Simon G. "Hyperfine and Zeeman measurements in the infrared spectrum of doubly charged molecule D'3'5 C1'2'+." Thesis, University of Newcastle Upon Tyne, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366641.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Döringshoff, Klaus [Verfasser], Achim [Gutachter] Peters, Heinz-Wilhelm [Gutachter] Hübers, and Leo [Gutachter] Hollberg. "Optical frequency references based on hyperfine transitions in molecular iodine / Klaus Döringshoff ; Gutachter: Achim Peters, Heinz-Wilhelm Hübers, Leo Hollberg." Berlin : Humboldt-Universität zu Berlin, 2018. http://d-nb.info/1182541704/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Schef, Peter. "Weak Atomic Interactions." Doctoral thesis, Stockholm : Physics Department, Stockholm University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1064.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Boucard, Stéphane. "Calcul de haute précision d'énergies de transitions dans les atomes exotiques et les lithiumoïdes : corrections relativistes, corrections radiatives, structure hyperfine et interaction avec le cortège électronique résiduel." Phd thesis, Université Pierre et Marie Curie - Paris VI, 1998. http://tel.archives-ouvertes.fr/tel-00007148.

Full text

Abstract:

Dans ce mémoire, nous présentons des calculs d'énergie de transition
dans les ions lithiumoïdes et les atomes exotiques : 1) Les nouvelles
sources rendent possible la fabrication d'ions lourds fortement
chargés. Nous nous sommes intéressés à l'étude de la structure
hyperfine des ions lithiumoïdes. Cela nous permet d'examiner les
problèmes relativistes à plusieurs corps et la partie magnétique des
corrections d'Electrodynamique Quantique (QED). Dans les ions lourds,
ces dernières sont de l'ordre de quelques pour-cents par rapport à
l'énergie totale de la transition hyperfine. Nous avons également
évalué l'effet de Bohr-Weisskopf lié à la distribution du moment
magnétique dans le noyau. Nous avons calculé puis comparé ces
différentes contributions en incluant les corrections radiatives
(polarisation du vide et self-énergie) ainsi que l'influence du
continuum négatif. 2) Un atome exotique est un atome dans lequel un
électron du cortège est remplacé par une particule de même charge :
$\mu^(-)$, $\pi^(-)$, $\bar(p)$\ldots Des expériences récentes ont
permis de gagner trois ordres de grandeur en précision et en
résolution. Nous avons voulu améliorer la précision des calculs
d'énergies de transitions nécessaires à la calibration et à
l'interprétation dans deux cas : la mesure de paramètres de
l'interaction forte dans l'hydrogène anti-protonique ($\bar(p)$H) et
la détermination de la masse du pion grâce à l'azote pionique
($\pi$N). Nos calculs prennent en compte la structure hyperfine et le
volume de la distribution de charge de la particule. Nous avons
amélioré le calcul de la polarisation du vide qui ne peut plus être
traitée au premier ordre de la théorie des perturbations dans le cas
des atomes exotiques. Pour les atomes anti-protoniques, nous avons
également ajouté la correction du g-2. Elle provient du caractère
composite de l'anti-proton qui de ce fait possède un rapport
gyromagnétique g $\approx$ -5.5856 .

APA, Harvard, Vancouver, ISO, and other styles

8

Fraval, Elliot, and elliot fraval@gmail com. "Minimising the Decoherence of Rare Earth Ion Solid State Spin Qubits." The Australian National University. Research School of Physical Sciences and Engineering, 2006. http://thesis.anu.edu.au./public/adt-ANU20061010.124211.

Full text

Abstract:

[Mathematical symbols can be only approximated here. For the correct display see the Abstract in the PDF files linked below] This work has demonstrated that hyperfine decoherence times sufficiently long for QIP and quantum optics applications are achievable in rare earth ion centres. Prior to this work there were several QIP proposals using rare earth hyperfine states for long term coherent storage of optical interactions [1, 2, 3]. The very long T_1 (~weeks [4]) observed for rare-earth hyperfine transitions appears promising but hyperfine T_2s were only a few ms, comparable to rare earth optical transitions and therefore the usefulness of such proposals was doubtful. ¶ This work demonstrated an increase in hyperfine T_2 by a factor of 7 × 10^4 compared to the previously reported hyperfine T_2 for Pr^[3+]:Y_2SiO_5 through the application of static and dynamic magnetic field techniques. This increase in T_2 makes previous QIP proposals useful and provides the first solid state optically active Lamda system with very long hyperfine T_2 for quantum optics applications. ¶ The first technique employed the conventional wisdom of applying a small static magnetic field to minimise the superhyperfine interaction [5, 6, 7], as studied in chapter 4. This resulted in hyperfine transition T_2 an order of magnitude larger than the T_2 of optical transitions, ranging fro 5 to 10 ms. The increase in T_2 was not sufficient and consequently other approaches were required. ¶ Development of the critical point technique during this work was crucial to achieving further gains in T_2. The critical point technique is the application of a static magnetic field such that the Zeeman shift of the hyperfine transition of interest has no first order component, thereby nulling decohering magnetic interactions to first order. This technique also represents a global minimum for back action of the Y spin bath due to a change in the Pr spin state, allowing the assumption that the Pr ion is surrounded by a thermal bath. The critical point technique resulted in a dramatic increase of the hyperfine transition T_2 from ~10 ms to 860 ms. ¶ Satisfied that the optimal static magnetic field configuration for increasing T_2 had been achieved, dynamic magnetic field techniques, driving either the system of interest or spin bath were investigated. These techniques are broadly classed as Dynamic Decoherence Control (DDC) in the QIP community. The first DDC technique investigated was driving the Pr ion using a CPMG or Bang Bang decoupling pulse sequence. This significantly extended T_2 from 0.86 s to 70 s. This decoupling strategy has been extensively discussed for correcting phase errors in quantum computers [8, 9, 10, 11, 12, 13, 14, 15], with this work being the first application to solid state systems. ¶ Magic Angle Line Narrowing was used to investigate driving the spin bath to increase T_2. This experiment resulted in T_2 increasing from 0.84 s to 1.12 s. Both dynamic techniques introduce a periodic condition on when QIP operation can be performed without the qubits participating in the operation accumulating phase errors relative to the qubits not involved in the operation. ¶ Without using the critical point technique Dynamic Decoherence Control techniques such as the Bang Bang decoupling sequence and MALN are not useful due to the sensitivity of the Pr ion to magnetic field fluctuations. Critical point and DDC techniques are mutually beneficial since the critical point is most effective at removing high frequency perturbations while DDC techniques remove the low frequency perturbations. A further benefit of using the critical point technique is it allows changing the coupling to the spin bath without changing the spin bath dynamics. This was useful for discerning whether the limits are inherent to the DDC technique or are due to experimental limitations. ¶ Solid state systems exhibiting long T_2 are typically very specialised systems, such as 29Si dopants in an isotopically pure 28Si and therefore spin free host lattice [16]. These systems rely on on the purity of their environment to achieve long T_2. Despite possessing a long T_2, the spin system remain inherently sensitive to magnetic field fluctuations. In contrast, this work has demonstrated that decoherence times, sufficiently long to rival any solid state system [16], are achievable when the spin of interest is surrounded by a concentrated spin bath. Using the critical point technique results in a hyperfine state that is inherently insensitive to small magnetic field perturbations and therefore more robust for QIP applications.

APA, Harvard, Vancouver, ISO, and other styles

9

Gonzalez, Gabriel. "ELECTRON TRANSPORT IN SINGLE MOLECULE MAGNET TRANSISTORS AND OPTICAL LAMBDA TRANSITIONS IN THE NITROGEN-VACANCY CENTER IN DIAMON." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2976.

Full text

Abstract:

This thesis presents some theoretical studies dealing with quantum interference effects in electron transport through single molecule magnet transistors and a study on optical non-conserving spin transitions in the Nitrogen-vacancy center in diamond. The thesis starts with a brief general introduction to the physics of quantum transport through single electron transistors. Afterwards, the main body of the thesis is divided into three studies: (i) In chapter (2) we describe the properties of single molecule magnets and the Berry phase interference present in this nanomagnets. We then propose a way to detect quantum interference experimentally in the current of a single molecule magnet transistor using polarized leads. We apply our theoretical results to the newly synthesized nanomagnet Ni4. (ii) In chapter (3) we review the Kondo effect and present a microscopic derivation of the Kondo Hamiltonian suitable for full and half integer spin nanomagnets. We then calculate the conductance of the single molecule magnet transistor in the presence of the Kondo effect for Ni4 and show how the Berry phase interference becomes temperature dependent. (iii) We conclude in chapter (4) with a theoretical study of the single Nitrogen vacancy defect center in diamond. We show that it is possible to have spin non-conserving transitions via the hyperfine interaction and propose a way to write and read quantum information using circularly polarized light by means of optical Lambda transitions in this solid state system.
Ph.D.
Department of Physics
Sciences
Physics PhD

APA, Harvard, Vancouver, ISO, and other styles

10

Cornish, Simon Lee. "A solid state laser system for high resolution spectroscopy of the 1S-2S transition in muonium." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297937.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

BOUCARD, STEPHANE. "Calcul de haute precision d'energies de transitions dans les atomes exotiques et les lithiumoides : corrections relativistes, corrections radiatives, structure hyperfine et interaction avec le cortege electronique residuel." Paris 6, 1998. http://www.theses.fr/1998PA066423.

Full text

Abstract:

Dans ce memoire, nous presentons des calculs d'energie de transition dans les ions lithiumoides et les atomes exotiques : 1) les nouvelles sources rendent possible la fabrication d'ions lourds fortement charges. Nous nous sommes interesses a l'etude de la structure hyperfine des ions lithiumoides. Cela nous permet d'examiner les problemes relativistes a plusieurs corps et la partie magnetique des corrections d'electrodynamique quantique (qed). Dans les ions lourds, ces dernieres sont de l'ordre de quelques pour-cents par rapport a l'energie totale de la transition hyperfine. Nous avons egalement evalue l'effet de bohr-weisskopf lie a la distribution du moment magnetique dans le noyau. Nous avons calcule puis compare ces differentes contributions en incluant les corrections radiatives (polarisation du vide et self-energie) ainsi que l'influence du continuum negatif. 2) un atome exotique est un atome dans lequel un electron du cortege est remplace par une particule de meme charge. Des experiences recentes ont permis de gagner trois ordres de grandeur en precision et en resolution. Nous avons voulu ameliorer la precision des calculs d'energies de transitions necessaires a la calibration et a l'interpretation dans deux cas : la mesure de parametres de l'interaction forte dans l'hydrogene anti-protonique et la determination de la masse du pion grace a l'azote pionique. Nos calculs prennent en compte la structure hyperfine et le volume de la distribution de charge de la particule. Nous avons ameliore le calcul de la polarisation du vide qui ne peut plus etre traitee au premier ordre de la theorie des perturbations dans le cas des atomes exotiques. Pour les atomes anti-protoniques, nous avons egalement ajoute la correction du g-2. Elle provient du caractere composite de l'anti-proton qui de ce fait possede un rapport gyromagnetique g-5. 5856.

APA, Harvard, Vancouver, ISO, and other styles

12

Hakhumyan, Hrant. "Study of optical and magneto processes in Rb atomic vapor layer of nanometric thickness." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00764958.

Full text

Abstract:

Using a narrow-band resonant fluorescence spectra from a nano-cell with a thickness of L= [lambda]/2, and VSOP resonances formed at a thickness L =[lambda] ([lambda] is the wavelength of the resonant radiation), for the first time it was experimentally investigated the behaviour of the frequency and intensity (transition probabilities) of the atomic hyperfine structure transitions between the 85Rb, 87Rb, D1 and D2 lines Zeeman sublevels in external magnetic fields in range 5 - 7000G. The behaviour of tens of previously unstudied atomic transitions was analyzed and it is demonstrated that the intensities of these lines can both greatly increase, and decrease (tenfold). For the first time it is demonstrated that, in the case of partial pressure of neon buffer gas up to 6~torr into the nano-cell of thickness L = [lambda] filled with Rb, VSOP resonances are recorded confidently, while the addition of 0.1~torr neon buffer gas in a cell of a centimeter thickness leads to the complete disappearance of VSOP resonances formed with the help of the widely used technique of saturated absorption. It is demonstrated for the first time that the spectral width of the resonant fluorescence spectra of the rubidium nano-cell with thickness L= [lambda]/2, for all values of the neon buffer gas pressures is much narrower (6-8 times) compared with the resonant fluorescence spectra of an ordinary centimeter cell containing rubidium with the same pressures of neon

APA, Harvard, Vancouver, ISO, and other styles

13

Meis, Constantin. "Étude de l'effet doppler du 2e ordre sur la transition hyperfine micro-onde à 40,5 Ghz du niveau fondamental ²S½ des ions ¹⁹⁹ Hg⁺ piégés dans une trappe radiofréquence." Paris 11, 1988. http://www.theses.fr/1988PA112313.

Full text

Abstract:

On a étudié les propriétés énergétiques des ions ¹⁹⁹Hg⁺ piégés dans une trappe radiofréquence cylindrique afin d'évoluer le décalage dû à l'effet Doppler du second ordre sur la raie de résonance à 40,5 Ghz de la transition hyperfine du niveau fondamental ²s ₁/₂. Cette étude, théorique et expérimentale, a été menée pour améliorer la précision de l'étalon de fréquence atomique à ion mercure 199. On a voulu, par ailleurs, donner un caractère général aux résultats déduits afin qu'ils puissent être applicables à n'importe quel type d'ions possédant une structure hyperfine, confiné dans une trappe radiofréquence quadrupolaire ou cylindrique. On a créé pour cela un formalisme analytique mettant en jeu des paramètres physiques pouvant être mesurés expérimentalement afin d'évaluer l'énergie cinétique moyenne des ions confinés, ce qui permet de connaitre l’effet Doppler du second ordre proportionnel à cette quantité. L'énergie cinétique moyenne calculée tient compte aussi bien de la contribution du macro-mouvement lent, qu'on a supposé thermalisé, que de celle du micromouvement rapide dû au champ de confinement. On a considéré un modèle thermalisé de la distribution des charges à l’intérieur d'un pseudo potentiel de confinement, tout en tenant compte du potentiel d'interaction électrique entre les tons piégés (charge d'espace). Ce formalisme permet, en outre, d'estimer la densité centrale du nuage ionique formé, ainsi que le potentiel de la charge d'espace. Les résultats ont été comparés à des calculs numériques de simulation, pour différentes conditions de confinement, montrant un très bon accord. Une étude numérique a permis d'étudier les propriétés de confinement du pseudo potentiel créé à l'intérieur d'une trappe radiofréquence cylindrique, afin d'adapter ce formalisme à nos conditions expérimentales. On a démontré que le potentiel efficace de cette trappe est très différent de celui d'une trappe hyperboloïde (quadrupolaire) radiofréquence. Les conditions de sphéricité et d'harmonicité du pseudo potentiel ont été définies, ainsi que la valeur de la fréquence théorique séculaire résultante. On a aussi déduit que des densités plus élevées (environ 25 %) peuvent être atteintes dans une trappe cylindrique pour les mêmes tensions de confinement. Le modèle a été appliqué à différentes conditions expérimentales en mesurant, à chaque fois, les paramètres physiques intervenant dans le formalisme, qui sont le nombre d'ions total et la fréquence du macro mouvement séculaire déplacée par la charge d'espace. On en a déduit que la température d'un nuage de 2 millions d’ions ¹⁹⁹Hg⁺, piégés dans un pseudo potentiel de fréquence séculaire théorique 40 khz, est typiquement de 3300 ± 100 K dans un vide résiduel de 10 ⁻⁸ Torr. Le déplacement du â l'effet Doppler du second ordre dans ce cas est : Δ f ÷ f = -(5,44 ± 0,16) 10⁻¹² En utilisant l'hélium comme gaz tampon, on a étudié le refroidissement collisionnel de ce nuage d'ions dans les mêmes conditions de confinement. La plus basse température mesurée est de 700 K pour une pression d'hélium de 3. 10 ⁻⁵ Torr. Le déplacement dû à l'effet Doppler du second ordre est, dans ce cas: Δ f ÷ f = - (1. 76 ± 0. 11 à 10⁻¹²). Finalement, on a mis en évidence la faible distorsion du pseudo potentiel due aux asymétries de la trappe cylindrique. Les irrégularités sont partiellement compensées par la forme particulière du potentiel efficace
We have studied the energy properties of 199Hg⁺ stored in an R. F. Cylindrical trap in order to evaluate the 2nd order Doppler effect on the resonance line at 40. 5 Ghz of the hyperfine transition of the fundamental level ²s ₁/₂. The purpose of this study, both experimental and theoretical, is to improve the precision of 199 mercury ions atomic frequency standard. Besides, we wanted to give a general caracter to the issued results so as they could be applied to all kinds of tons, with an hyperfine structure, stored in an R. F. Trap, quadrupole or cylindrical. We have established an analytical formalism, using physical parameters that can be measured experimentally, in order to estimate the mean kinetic energy of the stored ions, the 2nd order Doppler effect being directly proportional to this quantity. The mean kinetic energy calculated by this way takes into account the contribution of slow macromotion, supposed thermalized and that of rapid micromotion due to the confining field. We have assumed a thermalized charge density distribution in a confining pseudo potential taking also into account space charge affects. The above formalism also permits to evaluate the ion cloud central density as well as space charge potential. The results have been compared to those of numerical simulation methods for differents trapping conditions showing a very good agreement. We have then carried out a numerical study of the confinement properties of an R. F. Cylindritcal trop pseudo potential so as to adjust this formalism to our experimental conditions. We have thus demonstrated that the effective potentiel of such a trap is quite different to that of a quadrupole one. We have also defined the condition of an approximate sphericity and harmonicity of the pseudo potential as well as the value of the corresponding theoretical secular frequency. We have deduced that higher density (about 25 %) can be achieved in an R. F. Cylindrical trap than in a quadrupolar one for the same trapping parameters. The model has been applied to different experimental conditions measuring each time the necessary physical parameters which are the total ion number and the macromotion secular frequency shifted by space charge. We have concluded that the temperature of an ion cloud of 2. 10⁶ 199Hg+ ions trapped in a spherical pseudo potential of 40 khz is 3300 ± 100 k in a residual vacuum of 10⁻⁸ Torr. The 2nd order Doppler effect shift in this case is : Δ f ÷ f = -(5,44 ± 0,16) 10⁻¹². We have also studied the collisional cooling of an ion cloud for the same trapping conditions using helium buffer gas. At helium pressure of 3. 10⁻⁵ Torr we have measured a lower temperature of 700 ± 60 K. The corresponding 2nd order Doppler shift is: Δ f ÷ f = - (1. 76 ± 0. 11 à 10⁻¹²). Finally, we have put in evidence the weak distortion of the pseudo potential well of an R. F. Cylindrical trap due to the irregularities

APA, Harvard, Vancouver, ISO, and other styles

14

Stocki, Trevor J. "Measurement of muonic hyperfine transition rates and muon capture yields in light nuclei." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0024/NQ38983.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Razet, Annick. "Transitions hyperfines de l'iode moléculaire au service de la métrologie des fréquences optiques." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376179311.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Douay, Marc. "Analyses rotationnelle et hyperfine de la transition électronique A6[sigma+]-X6[sigma+] du radical MnS par spectroscopie d'absorption saturée." Lille 1, 1986. http://www.theses.fr/1986LIL10155.

Full text

Abstract:

L'étude a été réalisée à l'aide des spectroscopies d'excitation, de fluorescence dispersée, et d'absorption saturée, utilisant un laser à colorant continu monomode. Observation des perturbations de la structure rotationnelle de la bande 0-1 et confirmation de la présence d'une seconde transition de MnS vers 440 mm

APA, Harvard, Vancouver, ISO, and other styles

17

Douay, Marc. "Analyses rotationnelle et hyperfine de la transition électronique... du radical MnS par spectroscopie d'absorption saturée." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37597438j.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Volotka, Andrey V. "High-precision QED calculations of the hyperfine structure in hydrogen and transition rates in multicharged ions." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1164063385430-72550.

Full text

Abstract:

Studies of the hyperfine splitting in hydrogen are strongly motivated by the level of accuracy achieved in recent atomic physics experiments, which yield finally model-independent informations about nuclear structure parameters with utmost precision. Considering the current status of the determination of corrections to the hyperfine splitting of the ground state in hydrogen, this thesis provides further improved calculations by taking into account the most recent value for the proton charge radius. Comparing theoretical and experimental data of the hyperfine splitting in hydrogen the proton-size contribution is extracted and a relativistic formula for this contribution is derived in terms of moments of the nuclear charge and magnetization distributions. An iterative scheme for the determination of the Zemach and magnetic radii of the proton is proposed. As a result, the Zemach and magnetic radii are determined and the values are compared with the corresponding ones deduced from data obtained in electron-proton scattering experiments. The extraction of the Zemach radius from a rescaled difference between the hyperfine splitting in hydrogen and in muonium is considered as well. Investigations of forbidden radiative transitions in few-electron ions within ab initio QED provide a most sensitive tool for probing the influence of relativistic electron-correlation and QED corrections to the transition rates. Accordingly, a major part of this thesis is devoted to detailed studies of radiative and interelectronic-interaction effects to the transition probabilities. The renormalized expressions for the corresponding corrections in one- and two-electron ions as well as for ions with one electron over closed shells are derived employing the two-time Green's function method. Numerical results for the correlation corrections to magnetic transition rates in He-like ions are presented. For the first time also the frequency-dependent contribution is calculated, which has to be accounted for preserving gauge invariance. One-loop QED corrections to the magnetic-dipole transition amplitude between the fine-structure levels 2p_{3/2} and 2p_{1/2} are calculated to all orders in \alpha Z. Taking into account consistently relativistic, interelectronic-interaction, and QED corrections to the magnetic-dipole transition amplitude allows for predictions of the lifetimes of the states (1s^2 2s^2 2p)^2P_{3/2} in B-like ions and (1s^2 2s 2p)^3P_2 in Be-like ions with utmost precision. The results of corresponding calculations are compared with experimental data obtained in recent measurements at the Heidelberg EBIT. Finally, for He-like ions with nonzero-spin nuclei the effect of hyperfine quenching on the lifetimes of the 2^3P_{0,2} states is investigated and again compared available experimental data.

APA, Harvard, Vancouver, ISO, and other styles

19

Randtke, Jie Min. "Rotational Spectroscopy of Simple Metal Carbon Clusters: Resolving the Beauty of Fine and Hyperfine Interactions in Metal Monoacetylides and Metal Carbides." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/603492.

Full text

Abstract:

Pure rotational spectra of simple metal carbon clusters that relevant to transition metal synthesis and catalysis have been obtained using Fourier transform microwave (FTMW) techniques combined with millimeter-wave direct-absorption methods. Rotational spectra of metal acetylides (CuCCH, ZnCCH, Li/Na/KCCH, MgCCH, AlCCH, CrCCH), diatomic metal monocarbide (CrC) and T-shape metal dicarbides (YC₂ and ScC₂) were recorded in the 4–650 GHz frequency regime. Measurements of weaker isotoplogues including ⁶⁶ZnCCH, ⁶⁸ZnCCH, Zn¹³C¹³CH, ZnCCD, Li/Na/KCCD, CrCCD, Y¹³C¹²C, Y¹³C¹³C, Sc¹³C¹³C, were also studied to aid in structural determinations. This work is the first study of ZnCCH and ScC₂ by any type of spectroscopic technique. Hyperfine splittings in MgCCH and Li/Na/KCCH have also been resolved and the weak isotoplogues of YC₂ have been measured for the first time. Potential interstellar molecules ScO and FeCN were studied using the FTMW techniques in the 4–62 GHz frequency regime. Spectra of the zinc insertion product ClZnCH₃ were additionally recorded in the 10–30 GHz (FTMW) and 260–296 GHz (direct absorption) frequency ranges, along with weaker isotopologues Cl⁶⁶ZnCH₃ and Cl⁶⁸ZnCH₃. This works is the first measurement of zinc insertion products using the FTMW-DALAS techniques. The data were analyzed implementing an effective Hamiltonian, allowing for accurate spectroscopic parameters to be established. From rotational constants, the molecular geometries were accurately determined. Electronic properties were also assessed, including the degree of covalent vs ionic character in a chemical bond, and the molecular orbital composition. The fundamental physical and chemical properties of these benchmark species were obtained in order to gain insight into their role in larger molecular systems, test theoretical calculations, and, in certain cases, provide accurate rest frequencies for astronomical searches.

APA, Harvard, Vancouver, ISO, and other styles

20

CORDEIRO, MOACIR R. "Investigação de interações hiperfinas em Zn(1-x)MT(x)O, onde MT=(V, Cr, Mn, Fe, Co, Ni, Cu) pela técnica de correlação angular gama-gama perturbada." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10073.

Full text

Abstract:

Made available in DSpace on 2014-10-09T12:34:26Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:09:48Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

APA, Harvard, Vancouver, ISO, and other styles

21

Larico, Rolando. "Estrutura eletrônica e campo hiperfino de impurezas complexas de cobalto e de níquel em diamante." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-25032009-135707/.

Full text

Abstract:

As várias possibilidades de aplicações tecnológicas que o diamante permite, na indústria de dispositivos, impulsionaram os avanços de fabricação de amostras de diamante sintético de alta qualidade. O cristal de diamante crescido, do grafite, pela técnica de alta pressão e alta temperatura (HPHT - High Pressure-High Temperature), utiliza ligas de metais de transição como solvente-catalizadores, que produzem contaminação das amostras. Dentre as várias impurezas de metal de transição introduzidas no material resultante, as impurezas de níquel são as mais bem caracterizadas, pois os centros relacionados ao Ni apresentam características únicas nestas amostras sintéticas. Apesar das ligas de cobalto serem as mais utilizadas como solvente-catalizador no crescimento de diamante sintético, defeitos relacionados a sua presença, no material resultante, não têm sido identificados com a mesma facilidade como aqueles relacionados aos do níquel. Medidas de absorção óptica e de ressonância paramagnética eletrônica têm identificado vários centros relacionados com a impureza de níquel e alguns centros relacionados com a impureza de cobalto em diamante, tanto isolados como formando complexos, que envolvem defeitos intrínsecos e/ou dopantes. Entretanto, existem ainda muitas dúvidas e controvérsias sobre a estrutura microscópica destes centros.
High quality synthetic diamond, growth out of graphite, has been achieved by the high pressure-high temperature (HPHT) methods. In order to speed up the process and allow to get macroscopic samples, 3d-transition metal alloys have been used as solvent-catalysts. Those transition metals (TM) end up contaminating the samples, generating electrically and optically active centers. Nickel was the first transition metal impurity unambiguously identified in synthetic diamond, ever since, several nickel-related active centers have been observed. Although cobalt has been the most widely used solvent-catalyst to grow diamond, cobalt-related defects could not be identified as easily as the nickel-related ones. Electron paramagnetic resonance (EPR) and optical absorption measurements have identified several Ni-related centers and some Co-related centers in diamond, mostly isolated TM and TM-related complexes involving intrinsic defects and/or dopants. However, there is considerable controversy about the microscopic structure of those centers. We present a theoretical investigation on the structural and electronic properties of nickel and cobalt impurities in diamond. The atomic structures, symmetries, formation and transition energies, and hyperfine parameters of isolated interstitial and substitutional Ni and Co, as well as of the Ni-divacancy, Co-divacancy, Co-divacancy-nitrogen, Ni-B, and Ni-N complexes were computed by using ab initio total energy methods. Here we used the spin-polarized full-potential linearized augmented plane wave (FPLAPW) method. The calculations were performed within the framework of the density functional theory and considered the supercell approach. Our results are discussed in the context of the microscopic models which have been proposed to explain the active centers identified in synthetic diamond. Based on our results, we confirm some microscopic models and we ultimately propose new ones which unifies several experimentally identified impurities.

APA, Harvard, Vancouver, ISO, and other styles

22

PENDL, JUNIOR WILLI. "Estudo do campo hiperfino magnetico no sup181Ta no sitio Y das ligas de Heusler Cosub2 YAI (Y=Ta, Cr) e Cosub2 Ysup1sup1sub1-xYsup2subxZ (Y=Ti,V,Nb,Cr e Z=Al,Sn)." reponame:Repositório Institucional do IPEN, 1996. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10444.

Full text

Abstract:

Made available in DSpace on 2014-10-09T12:38:48Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T13:59:57Z (GMT). No. of bitstreams: 1 02804.pdf: 5729707 bytes, checksum: c667fdd5fc2e2f8e905f4ff2e50381bf (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

APA, Harvard, Vancouver, ISO, and other styles

23

Souiri, Moncef. "Correlation entre les parametres de resonance paramagnetiques et de la liaison chimique : ions des metaux de transition et muonium." Strasbourg 1, 1986. http://www.theses.fr/1987STR13213.

Full text

Abstract:

Recherche de relations entre parametres de l'hamiltonien de spin en rpe de defauts ponctuels (decomposition par le champ cristallin, constante de couplage hyperfin) et les parametres de la liaison chimique du reseau hote (ionicite, electronegativites de l'anion et du cation, longueur de liaison). Bonne correlation dans le cas de l'ionicite et de l'electronegativite de l'anion; absence de correlation avec la longueur de liaison, explicable par une relaxation locale, et mise en evidence dans les matrices ternaires. Application de l'analyse au muonium: la constante de couplage hyperfin est correlee a l'electronegativite du cation dans le cas du muonium normal, qui serait localise seulement dans les cristaux covalents; cette constante est tres faible pour le muonium anormal qui serait engage dans une liaison covalente avec le voisin le plus proche

APA, Harvard, Vancouver, ISO, and other styles

24

SOUZA, SYLVIO D. de. "Medidas de campos hiperfinos magneticos em ligas de Heusler do tipo Cosub2Yz(Y=Ti,Zr;Z=Al,Ga,Sn)." reponame:Repositório Institucional do IPEN, 1986. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10369.

Full text

Abstract:

Made available in DSpace on 2014-10-09T12:37:52Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:08:50Z (GMT). No. of bitstreams: 1 11262.pdf: 2088807 bytes, checksum: e62f93356490df3bf8bfb2ab45b5ce42 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

APA, Harvard, Vancouver, ISO, and other styles

25

Crispino, Ângela Burlamaqui Klautau. "Estudo das propriedades locais de impurezas substitucionais de FE em PD, SC, Y, TI e ZR." Universidade de São Paulo, 1995. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-05082013-163412/.

Full text

Abstract:

Neste trabalho determinamos a estrutura eletrônica em torno de uma impureza substitucional de Fe nos metais de transição Pd, Sc, Y, Ti e Zr. Para realizar estes cálculos utilizamos urn método de primeiros princípios dentro da aproximação de densidade local, o RS-LMTO-ASA (\"Real Space-Linear Muffin-Tin Orbital-Atomic Sphere Approximation\'\'). Os resultados encontrados para os momentos magnéticos são comparados com outros cálculos te6ricos da literatura, e com resultados experimentais, quando existentes. Em particular, para o sistema com uma impureza de Fe em Pd analisamos os mecanismos de formação do momento magnético gigante. No caso da impureza de Fe nos hospedeiros Sc, Y, Ti e Zr, onde dois sítios distintos são observados experimentalmente, os resultados deste trabalho ajudam a identificar o sítio magnético como sendo o sítio substitucional. Calculamos também o comportamento do deslocamento isomérico e do campo hiperfino no sitio de Fe nos vários sistemas. Os valores determinados apresentam, em geral, excelente concordância com os resultados experimentais disponíveis na literatura.
In this work we use a first principles method within the local density approximation, the RS-LMTO-ASA (Real Space-Linear Muffin-Tin Orbitals-Atomic Sphere Approximation) to study the electronic structure around substitutional Fe impurities in Pd, Sc, Y, Ti and Zr hosts. We compare our results for the local magnetic moments at the impurity site with those obtained by other methods in the literature and with experimental results when available. For the substitutional Fe impurity in Pd we investigate the formation of the giant magnetic moment, which appears in this system. For the Fe impurity in Sc, Y, Ti and Zr, where two different sites for the Fe are observed experimentally, our results can help with site identification. We show beyond any doubt that the magnetic site is associated with the substitutional Fe in these hosts. Finally we also calculate the isomer shift and hyperfine contact field at the Fe impurity in all the systems. The values are in general in excellent agreement with experiment and other calculations, when available in the literature.

APA, Harvard, Vancouver, ISO, and other styles

26

Meis, Constantin. "Etude de l'effet Doppler du 2e ordre sur la transition hyperfine microonde à 40.5 GHz du niveau fondamental ²S¹/ des ions¹⁹⁹ Hg⁺ piégés dans une trappe radiofréquence." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37616605d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

JUNQUEIRA, ASTROGILDO de C. "Estudo de interacoes hiperfinas em oxidos perovskitas do tipo La(MT)Osub(3) (MT=metais de transicao Fe, Cr, Mn e Co)." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11242.

Full text

Abstract:

Made available in DSpace on 2014-10-09T12:49:51Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T14:03:04Z (GMT). No. of bitstreams: 1 09826.pdf: 5905522 bytes, checksum: b0354cc2f21014da9657b88019b2b992 (MD5)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:99/07068-0

APA, Harvard, Vancouver, ISO, and other styles

28

Bréant, Christian. "Développement de lasers infrarouges accordables de haute pureté spectrale : application à la spectroscopie hyperfine des molécules HF et SF(6)." Paris 13, 1985. http://www.theses.fr/1985PA132010.

Full text

Abstract:

Les développements de deux spéctromètres de saturation à ultra-haute résolution dans le domaine infrarouge, l'un dans la région spectrale 9-12 mu m et l'autre accordable de 2,3 a 3,2 mu m sont exposés en detail. La stabilisation en fréquence d'un laser à CO(2) conventionnel ou guide d'ondes au niveau de la dizaine de hertz ainsi que l'obtention d'une stabilité meilleure que 1 khz pour le laser à centres colores soulignent le role cle de ces oscillateurs dans la chaine de raccordement de fréquence de l'horloge à cesium vers le domaine visible. L'étude des interactions hyperfines est presentée dans le cas des molécules diatomiques héteronucleaires (hf) et des toupies spheriques du groupe ponctuel O(h) (sf(6)). Grace a l'enregistrement de structures hyperfines tres bien resolues, de nombreux effets ont etes mis en evidence et interpretes à l'aide du formalisme tensoriel (dans le groupe (l)o(3) x O(h)) en particulier : l'interaction de spin-vibration (bande upsilon (3) de sf(6)), les mélanges d'états de types de symétrie differents (sf(6)), les corrections ro-vibrationnelles à l'interaction de spin-rotation (hf et sf(6)), les structures superhyperfines (sf(6))

APA, Harvard, Vancouver, ISO, and other styles

29

Nota, Matteo. "Modélisation du laser à iode et oxygène chimique : élargissement collisionnel de transitions hyperfines de l'iode atomique et exploration de la flamme de dissociation de l'iode moléculaire par l'oxygène singulet." Lyon 1, 1990. http://www.theses.fr/1990LYO10030.

Full text

Abstract:

Dans un premier temps, un rappel general du developpement suivi par les differents types de lasers chimiques est fait, en insistant sur les performances de chacun et les perspectives ouvertes dans ce domaine. Puis, l'importance des deux axes developpes autour du laser a iode et oxygene chimique est mise en evidence, ainsi que les tout derniers progres effectues dans chacun d'eux: le premier point, concernant la modelisation, un schema de la cavite optimale est donne et l'on insiste particulierement sur le role joue dans le temps d'extraction de l'energie laser, par la relaxation collisionnelle entre les etats hyperfins concernes de l'atome d'iode. Ce dernier aspect fait d'ailleurs l'objet d'un article ou les constantes en question sont determinees a partir de nouvelles experiences, avec une fiabilite bien superieure a ce qui existait auparavant dans le litterature. Le second point concerne l'etude du mecanisme de dissociation de l'iode moleculaire par l'oxygene singulet. Des resultats deja existants ont ete rappeles, et ce travail concerne surtout la determination du role d'etats reservoirs. A et le fondamental de l'iode moleculaire dans ce processus. L'etude experimentale a ete effectuee par fluorescence induite par laser et a permis le developpement d'une methode d'analyse par inversion de spectre. Cette methode est decrite ainsi que d'autres aspects fondamentaux des methodes semiclassiques les plus couramment utilisees (cf methode rkr). Ce travail a permis de conclure a plusieurs mecanismes de dissociation possibles, intervenant en plusieurs etapes et en concurrence entre eux. Ces mecanismes sont decrits, mais leur importance relative est encore inconnue

APA, Harvard, Vancouver, ISO, and other styles

30

Jöhren, Raphael [Verfasser], and Christian [Akademischer Betreuer] Weinheimer. "Spectroscopy of the hyperfine transition in lithium like bismuth at the ESR at GSI and an APD based single photon detector for laser spectroscopy on highly charged ions / Raphael Jöhren ; Betreuer: Christian Weinheimer." Münster : Universitäts- und Landesbibliothek Münster, 2013. http://d-nb.info/1141383691/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

CARBONARI, ARTUR W. "Estudo do campo hiperfino magnetico no sup181Ta no sitio Y das ligas de Heusler Cosub2YZ(Y=Ti,Nb,V e Z=Si,Ge,Sn e Ga)." reponame:Repositório Institucional do IPEN, 1992. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10308.

Full text

Abstract:

Made available in DSpace on 2014-10-09T12:37:09Z (GMT). No. of bitstreams: 0
Made available in DSpace on 2014-10-09T13:56:46Z (GMT). No. of bitstreams: 1 01909.pdf: 4337748 bytes, checksum: 86acf59a272732a64c336ea3408816ec (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

APA, Harvard, Vancouver, ISO, and other styles

32

Bouazza, Safa. "Étude de la structure hyperfine de as i, pt ii, au ii, pb ii et bi ii et du déplacement isotopique de pt ii et pb ii par interférométrie Fabry-Pérot dans l'ultraviolet lointain." Brest, 1987. http://www.theses.fr/1987BRES2027.

Full text

Abstract:

L’interprétation théorique des résultats expérimentaux repose sur des calculs "a priori" menés au moyen d'un programme Dirac-Foch multiconfigurationnel auquel s'ajoutent d'autres calculs par méthode de Racah dans le formalisme de Judd pour la structure hyperfine

APA, Harvard, Vancouver, ISO, and other styles

33

Tu, Peng. "Etude des canaux TRPC6 sensibles au diacylglycérol dans les neurones de cortex de souris et de leurs rôles dans le transport de métaux de transition." Phd thesis, Université Joseph Fourier (Grenoble), 2009. http://tel.archives-ouvertes.fr/tel-00529360.

Full text

Abstract:

Les canaux TRPC6 sont des canaux cationiques non sélectifs qui peuvent être activés par le diacylglycérol (DAG). Ils sont présents dans de nombreux tissus et types cellulaires, notamment dans le cortex de souris embryonnaire (à E13). Des expériences d'imagerie calcique réalisées sur des neurones de cortex de souris en culture ont révélé la présence de canaux cationiques activés par le DAG. Ils sont perméables aux ions Ca2+, Na+, Ba2+ et Mn2+. L'entrée de Ca2+ via ces canaux est indépendante de la protéine kinase C et elle est bloquée par le SKF-96365 et le Gd3+. Par ailleurs, l'acide flufénamique augmente l'amplitude des réponses calciques induites par le DAG. Des expériences d'électrophysiologie réalisées avec la technique du patch-clamp en configuration cellule entière ont montré que l'hyperforine, un activateur des canaux TRPC6, donne naissance à un courant cationique non sélectif, confirmant ainsi l'existence de canaux de type TRPC6 dans les neurones corticaux. Des analyses quantitatives en spectrométrie d'émission atomique à plasma couplé inductif, en spectrométrie d'absorption atomique et en fluorescence X avec la nanosonde synchrotron (µ-SXRF) révèlent que la surexpression de TRPC6 dans les cellules HEK-293 s'accompagne d'une augmentation du contenu intracellulaire en zinc, en soufre et en manganèse. Les résultats obtenus avec des sondes fluorescentes sensibles au zinc et au fer indiquent que les canaux TRPC6 peuvent transporter ces cations. Par ailleurs, les expériences en µ-SXRF montrent que l'activation des canaux TRPC6 en présence de fer induit une accumulation de ce métal dans les cellules HEK et les neurones. Au cours de notre étude, nous avons également mis en évidence l'action de deux agents (l'acide flufénamique et l'hyperforine), couramment utilisés pour modifier l'activité des canaux TRPC6, sur la physiologie mitochondriale et l'homéostasie des métaux. En effet, l'acide flufénamique et l'hyperforine non seulement modifient le fonctionnement des canaux TRPC6 mais ils exercent aussi une action de type découplante sur les mitochondries, provoquant une libération de Ca2+ et de Zn2+ à partir de ces organelles.

APA, Harvard, Vancouver, ISO, and other styles

34

Ait, Bahammou Abdellah. "Application de l'effet Mössbauer à l'étude de milieux désordonnés : alliages terre rare-fer hydrogénés et verres de spin." Grenoble 1, 1986. http://www.theses.fr/1986GRE10098.

Full text

Abstract:

Etude par effet moessbauer de **(57)fe de l'occupation en fonction de sa concentration x des sites interstitiels tetraedriques, par l'hydrogene dans erfe::(2)h::(x). Comparaison des champs hyperfins sur les noyaux de fer aux moments magnetiques obtenus par diffraction de neutrons. Etude des alliages au::(0,96)fe::(0,03)sn::(0,01) (verre de spin) et au::(0,79)fe::(0,19)sn::(0,02) (ferromagnetique reentrant) par effet moessbauer sur **(57)fe et **(119)sn. Mise en evidence d'amas ferromagnetiques dans au::(0,79)fe::(0,19)sn::(0,02) par etude moessbauer en presence de champ applique

APA, Harvard, Vancouver, ISO, and other styles

35

SCHELL, JULIANA. "Investigação de parâmetros hiperfinos dos óxidos semicondutores SnOsub(2) e TiOsub(2) puros e dopados com metais de transição 3d pela espectroscopia de correlação angular gama-gama perturbada." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23699.

Full text

Abstract:

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-06-09T18:22:48Z No. of bitstreams: 0
Made available in DSpace on 2015-06-09T18:22:49Z (GMT). No. of bitstreams: 0
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

APA, Harvard, Vancouver, ISO, and other styles

36

Nabli, Hassan. "Étude par résonance magnétique nucléaire et spectroscopie Möessbauer de l'ordre local dans les alliages amorphes CO : :(x) sn::(1-x)." Nancy 1, 1987. http://www.theses.fr/1987NAN10078.

Full text

Abstract:

Étude par RMN de CO**(59) et par effet Moessbauer de SN**(119) avec et sans champ appliqué. On montre que l'ordre local autour d'un CO n'est pas aléatoire. L'analyse des spectres Moessbauer indique que les sites d'étain préférentiels dans l'amorphe sont constitués par les étains au centre d'un prisme trigonal d'atomes de cobalt. Les modèles d'empilement semblent être de motifs tetrahédriques

APA, Harvard, Vancouver, ISO, and other styles

37

Bonnisseau, Dominique. "Etude des structures magnétiques de composés de neptunium (NpAs, NpSb, NpSe et NpRu2Si2)." Grenoble 1, 1987. http://www.theses.fr/1987GRE10144.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Karr, Jean-Philippe. "Optique quantique dans les microcavités semi-conductrices. Spectroscopie de l'ion moléculaire H2+." Habilitation à diriger des recherches, Université d'Evry-Val d'Essonne, 2008. http://tel.archives-ouvertes.fr/tel-00347825.

Full text

Abstract:

Je présente dans une première partie mes travaux de recherche sur les microcavités semi-conductrices en régime de couplage fort exciton-photon. Les modes propres dans ces systèmes sont des états mixtes exciton-photon appelés polaritons de cavité, qui présentent de fortes non-linéarités optiques provenant de l'interaction exciton-exciton. Je présente plusieurs applications de ces dispositifs dans les domaines de l'optique quantique (compression du bruit quantique, génération de faisceaux corrélés) des communications optiques et de l'opto-électronique de spin.

J'aborde dans la deuxième partie mes activités théorique et expérimentale autour de la spectroscopie de l'ion H2+. Le but de l'expérience, qui a débuté en 2003 à l'université d'Evry, est de mesurer la fréquence d'une transition vibrationnelle à deux photons sans effet Doppler, et de la comparer à des prédictions théoriques précises pour en déduire une nouvelle détermination du rapport mp/me. Je décris les progrès des calculs de haute précision sur l'ion H2+ (niveaux d'énergie non relativistes, structure hyperfine), ainsi que le dispositif expérimental mis en place et les perspectives de l'expérience.

APA, Harvard, Vancouver, ISO, and other styles

39

Potin, Yves. "Spectrométrie Mössbauer in situ : application a l' étude de perovskites non-stoechiométriques et de fluorures d'étain." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1986. http://tel.archives-ouvertes.fr/tel-00204092.

Full text

Abstract:

Mise au point d'un appareillage permettant des études in situ de réactions solide-gaz dans une large gamme de températures; étude de différentes phases du système SrFeO3-y(y = 0,5-1) en fonction de la température et de la pression partielle d' oxygène; étude des composes du système SnF2 - SnF4 et établissement d' une corrélation entre les paramètres Mössbauer et les propriétés structurales.

APA, Harvard, Vancouver, ISO, and other styles

40

CHEN, TING-JU, and 陳亭儒. "Cesium 6S1/2-6D3/2 hyperfine transitions : absolute frequency and hyperfine structure." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5x3af2.

Full text

Abstract:

碩士
國立中央大學
物理學系
105
We developed an 885-nm frequency stabilized laser system locked via Cesium 6S1/2-6D3/2 crossover-line transition with electro-optical modulator. The stability of laser frequency is 10-12 at 200-seconds average time. We offset locked a slave laser to probe the hyperfine structure of Cesium 6D3/2 via the Doppler free two-photon transition spectra. After extrapolating the light shift and the Zeeman shift, the Cesium 6D3/2 coupling constants A and B and C are determined as A=16.3351(8) MHz; B=-0.092(9) MHz; C=0.0029(4) MHz, which is the first time to our knowledge pushing the spectral resolution to C constant in this transition. Besides, to avoid any collision shift by alien gas, we performed the absolute frequency measurement of 6S1/26D3/2 transition with a cesium cell whose vacuum was always kept at 10-10 by an ion pump. We obtained the value of 338 595 897 162 (51) kHz for 6S1/2 F=4 - 6D3/2 F=5 and 338 600 493 491 (15) kHz for 6S1/2 F=3 - 6D3/2 F=5 respectively.

APA, Harvard, Vancouver, ISO, and other styles

41

Liao, Wen-Sheng, and 廖文聖. "Cesium 6S-6D two-photon transitions and hyperfine coupling constants." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/18662686842771526666.

Full text

Abstract:

碩士
國立中央大學
物理學系
103
We constructed an 885 nm frequency stabilized diode laser system. We locked the 885 nm laser to Cs atom 6S1/2 F=3 to 6D 3/2 F=5 transition and scanned the frequency of carrier of the diode laser to obtain the hyperfine structure of 6D3/2. Similarly, we locked the 885 nm laser frequency to Cs atom 6S 1/2 F=4 to 6D3/2 F=3 transition and scanned the frequency of carrier of the diode laser to obtain hyperfine structure of 6D3/2. In the end, we deduced that the hyperfine coupling constant via the measuring of 6D3/2 hyperfine interval. In this work, for the hyperfine interval of 6S1/2 F=3 to 6D 3/2 F=2 to 5 that we measured were 81.767(29) MHz, 65.315(19) MHz and 49.148(23) MHz. The hyperfine coupling constants A and B that we deduced were 16.346(2) and 0.058(17). Similarly, the hyperfine interval of 6S1/2 F=4 to 6D3/2 F=2 to 5 that we measured were 81.763(17) MHz, 65.320(19) MHz and 49.149(3) MHz. The hyperfine coupling constants A and B that we deduced were 16.331(3) and 0.067(16) Other purposes of this work are to provide a frequency reference for Ti-Sapphire laser. In the past, our lab made a self-reference comb laser by referring to a Cs clock. In this work, we constructed a stabler frequency comb laser by directly referring the mode-locked laser to a cesium atom two-photon transition at 822 nm and 885 nm.

APA, Harvard, Vancouver, ISO, and other styles

42

蕭伃真. "Frequency Measurement of Molecular Iodine Hyperfine Transitions at 548.5 nm." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/98302178798677346324.

Full text

Abstract:

碩士
國立清華大學
物理系
100
The iodine stabilization system is usually used as an optical frequency standard. We report the absolute frequency measurement of 127I2 P(28) (24-0) lines. The frequency of iodine transitions is several GHz away from the Li+ ion transition and can be used as reference for lithium ion spectroscopy. In this experiment, we use 1097 nm external-cavity diode laser and a double system to produce 548.5 nm light, and use modulation transfer spectroscopy to obtain the iodine spectrum. We measure a1, a10, a15 lines, and they are measured at a vapor pressure of 7.8 Pa. As a result, we correct them by the pressure shift which is measured to be 8.9(1.2) kHz/Pa. The final results of the a1, a10, a15 are 546437908826(12) kHz, 546438483384(12) kHz, and 546438771985(12) kHz respectively. The results agree with the calculated values of IondineSpec5. The effect of pressure and power broadening are also investigated. For the future work, we will measure other transitions of molecular iodine between 540-550 nm, and some of them can also be used as references for lithium ion spectroscopy.

APA, Harvard, Vancouver, ISO, and other styles

43

Wang, Chun-Ju, and 王淳㚢. "Investigation of Zeeman Effect of Molecular Iodine Hyperfine Transitions at 548 nm." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/81935963528701812868.

Full text

Abstract:

碩士
國立清華大學
物理系
102
In many experiments, the iodine-stabilized laser system serves as an optical frequency standard. However, the geomagnetic field is usually not taken into consideration when measuring frequencies of molecular iodine hyperfine transitions. Up to now, the research on how the magnetic field affects absorption spectra of I2 hyperfine transitions is very limited because I2 is not sensitive to the magnetic field. The reason why spectra changes under the magnetic field is the difference in g-factor for different energy levels. As a result, each transition between Zeeman sublevels will exhibit different Zeeman shift. 　　In our experiment, the absorption spectra of 127I2 R(136) 27-0, R(86) 25-0, P(28) 24-0 and R(32) 24-0 hyperfine transitions are observed, and the linewidth of a10-lines is measured. By the superposition of several Lorentzian profiles, the difference of g_F-factors between the excited and ground state is calculated, and the average values of that under different magnetic fields are 0.0935, 0.0765, 0.0617 and 0.0571 respectively. Although the effect of the magnetic field on 127I2 hyperfine transitions at 548.5 nm is not theoretically investigated, the observed spectra can be reasonably explained and expected by the difference of g_F-factor obtained. In the future, more 127I2 hyperfine transitions under different magnetic fields can be investigated and better–controlled magnetic fields can be applied to get more precise g_F-factors.

APA, Harvard, Vancouver, ISO, and other styles

44

Lin, Chia-wei, and 林佳緯. "Sub-mHz-coherence optical offset locking for high-resolution cesium 6S-6D hyperfine transitions." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/33602635501528318876.

Full text

Abstract:

碩士
國立中央大學
物理學系
104
We tried to make frequency difference of two lasers be stable by some offset locking. Using different approaches, we successfully offset locked the frequency of one diode laser (slave laser) against the other frequency-stabilized laser (master laser), resulting in a highly stable frequency difference. A novel and simple scheme of electronic offset locking includes phase detector, PI loop filter is reported. For boosting up the beat-note power, we also built up a tracing oscillator with which a freency counter-based device was installed for extending the capture range. We use both digital and analogic phase detector to demonstrate the optical offset locking. We used different approaches to measure 3-dB linewidth of beat-note. The best design can make the 3-dB linewidth of beat-note be smaller than 1 mHz. The master laser was a diode laser having an independent frequency locking system that could serve as a stable reference frequency of slave laser. To sum up, we can control optical offset locking to monitor cesium 6S1/2-6D2/3 hyperfine transitions by two approaches. The purpose is to scan cesium hyperfine transitions by changing the frequency of slave laser, using the developed offset locking technique in this thesis.

APA, Harvard, Vancouver, ISO, and other styles

45

Chang, Chun-Yu, and 張君瑀. "Absolute frequency measurements of molecular iodine hyperfine transitions at 535 nm and 730 nm." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/01023309976899911763.

Full text

Abstract:

碩士
國立清華大學
光電工程研究所
101
Precision measurements of optical frequency play important roles in defining physical constants, investigating atomic and molecular structures, and testing physical principles. Optical frequency comb (OFC) directly links the radio frequency standards to optical frequency regime. In addition to optical frequency metrology, OFC grows the research of optical clocks and applications in astronomy. 　　The repetition rate and offset frequency of our Ti:sapphire-based OFC are phase-locked a global positioning system (GPS) disciplined Rb clock. It can use to measuring the absolute frequency of wavelength from 500 to 1100 nm. The accuracy of our OFC is better than 1×〖10〗^(-12) at a 1000 s integration time. After phase locking, the standard deviation of the repetition rate and offset frequency are 3 mHz and 10 mHz respectively at 1 s gate time of the frequency counter. 　　In this thesis, we perform two frequency measurements of molecular iodine hyperfine transitions, and in both experiments the laser frequency is stabilized to the center of hyperfine transitions. One is the absolute frequency measurements of the a_1, a_10, a_15 hyperfine components of molecular iodine P(28) 30-0 line at 535 nm. We obtain the zero-pressure absolute frequencies and the accuracy is 11 kHz. 　　The other is the absolute frequency measurements of molecular iodine reference frequencies for 1S-2S spectroscopy in muonium, hydrogen, and deuterium. We measure the absolute frequencies of R(26) 5-13 a_15, P(258) 7-11 a_15 and R(137) 5-12 a_(19-21) hyperfine components of iodine near 730 nm. Our preliminary results are more precise than previous measurements, but our results show a difference of 500 kHz to 1.2 MHz from the previous results.

APA, Harvard, Vancouver, ISO, and other styles

46

Mbaebie, Kingsley Okwuchukwu. "Calculation of forbidden-doublet separations and intensity of allowed and forbidden-hyperfine transitions in the EPR spectrum of transition-metal complexes." Thesis, 1989. http://spectrum.library.concordia.ca/2655/1/ML49044.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Fraval, Elliot. "Minimising the Decoherence of Rare Earth Ion Solid State Spin Qubits." Phd thesis, 2005. http://hdl.handle.net/1885/47058.

Full text

Abstract:

This work has demonstrated that hyperfine decoherence times sufficiently long for QIP and quantum optics applications are achievable in rare earth ion centres. Prior to this work there were several QIP proposals using rare earth hyperfine states for long term coherent storage of optical interactions. The very long T_1 (~weeks ) observed for rare-earth hyperfine transitions appears promising but hyperfine T_2s were only a few ms, comparable to rare earth optical transitions and therefore the usefulness of such proposals was doubtful. ¶ This work demonstrated an increase in hyperfine T_2 by a factor of 7 × 10^4 compared to the previously reported hyperfine T_2 for Pr^[3+]:Y_2SiO_5 through the application of static and dynamic magnetic field techniques. This increase in T_2 makes previous QIP proposals useful and provides the first solid state optically active Lamda system with very long hyperfine T_2 for quantum optics applications. ¶ ...

APA, Harvard, Vancouver, ISO, and other styles

48

Huang, Shin-Wei, and 黃信偉. "Comb Laser Referring to 133Cs Hyperfine Transition." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/d36ddt.

Full text

Abstract:

碩士
國立東華大學
應用物理研究所
94
Femto-second optical frequency comb laser were invented on years 2000, which causes a great revolution on the metrological applications and becomes the main achievements of the Nobel prize winner 2005 in Physics. However, up to now, just few experiments doing high resolution spectroscopy using comb laser. The main reason is that the available comb power is too weak to be delivered to user. Therefore, in this thesis, we develop a new way on making an optical frequency comb laser which available power could be promoted for using in high-resolution spectroscopy. Our approach is to make a comb laser by directly referring to a Cesium two-photon transition on 822.5 nm wavelength region. In this thesis, we describe our methods including: Laser repetition locking using phase lock loop; the arrangement of high power pump laser; the construction of Ti:sapphire laser system, the producer of locking absolute frequency of comb laser; and so on.

APA, Harvard, Vancouver, ISO, and other styles

49

Lin, Shih-Yin, and 林詩茵. "Abnormal pressure shift during atomic cesium 6S --> 8S hyperfine transition." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/44625282036438344276.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Eastwood, Michael William. "Searching for the Cosmic Dawn with the Hyperfine Structure Transition of Hydrogen." Thesis, 2019. https://thesis.library.caltech.edu/11547/1/eastwood_michael_2019.pdf.

Full text

Abstract:

The 21 cm hyperfine structure transition of neutral hydrogen promises to open a window into the first billion years of the Universe (z > 6). With the exception of rare lines of sight towards exceptionally distant and luminous galaxies, this period of the universe's history remains largely unexplored. During this time the 21 cm transition is expected to be detectable as a 10--100 mK perturbation in the thermal Cosmic Microwave Background (CMB) spectrum.

Due to the large field of view of low frequency radio telescopes (typically composed of dipole antennas) and the fact that the line of sight distance can be inferred from the measured frequency of the transition, the ultimate goal of 21 cm cosmology is to produce three dimensional tomographic maps of the 21 cm brightness temperature. In this way, the formation of the first stars and galaxies will be revealed through their influence on the neutral gas around them.

This thesis saw the construction of the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA), a new low frequency (27--85 MHz) radio telescope located near Bishop, California. Composed of 288 crossed-dipole antennas, the OVRO-LWA is capable of imaging the entire visible hemisphere in a single 13 s snapshot image with 8 arcmin angular resolution.

The primary challenges faced by efforts to detect the highly redshifted 21 cm transition are seeing past the blinding glow of foreground radio emission that is five orders of magnitude brighter than the cosmological emission, and calibrating the instrument to a level where it's possible to make the separation between foreground emission and the 21 cm signal. In this thesis I will present foundational work using the OVRO-LWA to place upper limits on spatial fluctuations of the 21 cm transition during the Cosmic Dawn---the period of first star formation.

In this thesis I present the highest angular resolution maps of the full sky below 100 MHz, and generated with a new widefield imaging technique that is specialized for drift scanning interferometers. These sky maps are a 10-fold improvement in angular resolution over existing maps at comparable frequencies, and are publicly available now for use in modeling and subtracting the contamination of foreground emission in 21 cm experiments.

Using a 28 hr integration with the OVRO-LWA, I place to-date the most constraining upper limits on the amplitude of the 21 cm spatial power spectrum at the Cosmic Dawn, and the first limits at z > 18. Although the current constraints Δ₂₁² ≲ (10⁴mK)² do not meaningfully restrict the parameter space of models of early star formation, they do inform the design and calibrations necessary for future measurements to push towards a detection of the high-redshift 21 cm transition. In making this measurement I demonstrate the application of a new foreground filter that accounts for the full covariance of the foreground emission, and provide an updated measurement of the foreground angular covariance. Finally, I interpret the limiting factors in this measurement and determine the instrumental calibration and characterization requirements the OVRO-LWA will need to achieve in order to make a detection of the 21 cm power spectrum of the Cosmic Dawn.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Hyperfine transitions'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles