Dissertations / Theses: 'Doppler-spectroscopy'

1

Hong, Xichun. "Doppler Shifted Fourier Transform Emission Spectroscopy /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487929745336654.

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CAPRON, BARBARA ANNE. "TWO-PHOTON MULTIWAVE MIXING (DOPPLER-FREE SPECTROSCOPY)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183854.

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This dissertation examines aspects of the interaction of multiple coherent light fields for the two-photon two-level model. In this model the interacting energy levels are not connected by an atomic dipole and a two-photon transition between them is necessary. We employ the density matrix formalism allowing easy comparison between the one- and two-photon two-level models. Significant differences are found due to dynamic Stark shifts and conjugate scattering off the pump-induced two-photon coherence. Averages over Doppler broadening are performed and the new upper-level relaxation mechanisms of decay to an intermediate nonresonant level and ionization from the upper state are included. The new relaxation mechanisms, introduced to the theory to better model experiments, are similar except that ionization is intensity dependent. They cause the resulting probe absorption spectra to become more complex and in general asymmetric. Doppler broadening is also important in experiments using gases. We analytically average over a Lorentzian velocity distribution for both co- and counterpropagating pump and probe beams. For copropagating fields the results are similar to those for the one-photon case averaged over inhomogeneous broadening, whereas counterpropagating pump and probe fields yield the so-called Doppler-free configuration that is normally only modelled to third order in the pump amplitude. We consider the pump field amplitude to all orders and find that as long as the width of the Doppler velocity distribution is significantly larger than the two-photon Rabi frequency the results are Doppler-free. The final part of the dissertation treats the question of two-photon squeezed states. This requires quantized sidemodes. Squeezed states are minimum uncertainty states with unequal variances in the two quadratures of the electromagnetic field amplitude. One way to generate these states is via multiwave mixing and we present here the first calculation for nondegenerate two-photon multiwave mixing as it applies to squeezed states. We find that in general two-photon squeezed states require lower intensities and detuning than those predicted by the one-photon model.

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程曦敏 and Hei-man Anita Ching. "Detector noise reduction in positron doppler broadening related spectroscopy systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31225846.

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Tolchard, J. M. "Doppler free laser spectroscopy of atomic hydrogen using pulsed lasers." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383868.

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Ching, Hei-man Anita. "Detector noise reduction in positron doppler broadening related spectroscopy systems /." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25212114.

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Bakule, Pavel. "A solid state laser system for Doppler-free spectroscopy of muonium." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365885.

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Rowan, Michael E. "Doppler-Free Saturated Fluorescence Spectroscopy of Lithium Using a Stabilized Frequency Comb." Oberlin College Honors Theses / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1368804208.

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8

Persaud, Michael Alan. "Doppler-free two-photon spectroscopy of one electron atoms using pulsed lasers." Thesis, University of Southampton, 1991. https://eprints.soton.ac.uk/361600/.

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In two independent experiments, frequency doubled pulse amplified dye laser light has been used in performing Doppler-free two-photon spectroscopy of the 1S½−2S½ transition in atomic hydrogen and muonium. Absolute values gained for the 1S½−2S½ transition frequencies were 2466 061 416(9) MHz and 2455 528 964(72) MHz for hydrogen and muonium respectively. Values for the ground state Lamb shifts were inferred to be 8171(9) MHz for hydrogen and 8079(73) MHz for muonium. All results were found to be in agreement with current quantum electrodynamic (QED) theory. Assuming QED theory to be accurate, then the hydrogen experiment yielded a new value for the Rydberg constant of 109 737 31.58(4) m−1, which is in agreement with other independent measurements. A separate experiment demonstrated a novel and general technique for efficiently frequency doubling mode-locked laser light, based on second harmonic generation inside an actively stabilised external ring enhancement cavity. When applied to a synchronously pumped mode-locked dye laser, over 100mW average power of tunable light around 243nm was available from the system corresponding to crystal conversion efficiencies in excess of 55%. A simple theoretical model successfully described the performance of this system. FM sideband frequency stabilisation of mode-locked lasers is treated both theoretically and experimentally. For the mode-locked dye laser, a frequency stability to within 500kHz relative to a reference interferometer was routinely possible. The frequency stabilised tunable uv light is ideal for performing Doppler-free coherent multiple pulse spectroscopy and may find application in the synchronous pumping of optical parametric oscillators or in selectively breaking chemical bonds.

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9

Jones, D. G. "Fluid phase behaviour in porous media studied by Doppler broadening position annihilation spectroscopy." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637461.

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A comprehensive Doppler broadening positron annihilation spectroscopy study of the confined phase behaviour of pure Argon, pure Krypton and their binary mixtures has been carried out by the author, within the Physics department at the University of Wales Swansea and the results of this work are presented in this thesis. Analysis of changes in photon energy spectra, resulting from positron annihilation within the sample, has yielded clear information regarding the state of the sample fluid confined in the nanometer pores of VYCOR glass. In particular, isothermal and isobaric experiments were performed in order to elucidate the location of confined phase transitions in terms of fluid temperature or pressure. The hysteresis associated with confined phase transitions was also investigated, for both freezing/melting and condensation/evaporation. In tandem with this work, a variable energy positron beam study was also undertaken, at the Technical University of Delft in the Netherlands. In particular, the Ni-SiC system and the thermal nature of the Schottky and Ohmic contacts was investigated.

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Maeda, Shigenori. "Characterization of aerosols with laser doppler velocimetry for LC/ICPMS." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27110.

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Gendron, Denis Julien. "Dynamics of HI photodissociation in the A band absorption via H-atom Doppler spectroscopy." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21348.pdf.

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12

Hara, Takayuki. "A calculation of fermi energy in selected materials using doppler broadened positron annihilation spectroscopy." Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/20238.

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Wyngaard, Adrian Leigh. "Saturated absorption spectroscopy of rubidium and feedback control of LASER frequency for Doppler cooling." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2621.

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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2018.
This research investigates the absorption spectra of rubidium and the feedback control of an external cavity diode laser. This research is a necessary prerequisite for laser (Doppler) cooling and trapping of rubidium atoms. Cooling rubidium atoms down to such low temperatures can be achieved using the Doppler cooling technique. Here a laser is tuned to remain resonant with a speci c atomic transition. To do this, the absorption spectra of rubidium must therefore be observed. All of the above require a reasonable knowledge about topics such as atomic physics, laser cooling and trapping, feedback control systems, and absorption spectroscopy. A discussion of these topics is provided. We have utilised an experimental setup which allowed for measurements of the Doppler broadened and Doppler free absorption spectra of rubidium, as well the analysis of the Zeeman e ect on the Doppler free spectra. The setup consisted of a saturated absorption spectrometer for high resolution spectroscopy and a Michelson interferometer for calibrating our measurements. In analysing the Zeeman e ect we added a set of Helmholtz coils to the saturated absorption spectroscopy arrangement to measure the splitting of the hyper ne energy levels.
French South African Institute of Technology (F'SATI) National Research Foundation

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Adamov, Minja Gemisic. "Measurements of local electric fields by doppler-free laser spectroscopy of hydrogen resonance lines." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2007. http://dx.doi.org/10.18452/15576.

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In dieser Arbeit wurde eine einfache laserspektroskopische Messmethode für lokale elektrische Feldstärken im Hinblick auf ihre Messmöglichkeiten und -grenzen untersucht. Als empfindliche optische Feldsensoren dienen dabei Wasserstoffatome, für die die Stark-Aufspaltung der Spektrallinien im elektrischen Feld wohl bekannt und exakt berechenbar ist. Die experimentellen Untersuchungen wurden an einer Niederdruck-Gaszelle durchgeführt, in der ein elektrisch geheizter Wolframdraht für thermische Dissoziation von Wasserstoffmolekülen sorgte. Die Wasserstoffatome wurden durch zwei gegenläufige Laserstrahlen Doppler-frei angeregt. Die Durchstimmung der schmalbandigen Laserstrahlung über den Wellenlängenbereich der Zwei-Photonen-Resonanz lieferte direkt das vom elektrischen Feld hervorgerufene Stark-Spektrum des angeregten Zustands. Weil die Methode im Gegensatz zu ähnlichen, erheblich aufwendigeren Verfahren nur die niedrigsten Wasserstoff-Energieniveaus benutzt, die mit Zwei-Photonen-Anregung direkt aus dem Grundzustand erreichbar sind, kommt sie mit einem einzigen Laser aus. Für das erste angeregte Niveau mit n = 2 wird Strahlung bei 243 nm benötigt, das nächsthöhere Niveau mit n = 3 erfordert 205 nm. Für n = 2 wurden Untersuchungen an Wasserstoff und Deuterium durchgeführt und Stark-Spektren mittels optogalvanischer Detektion gemessen. Schwerpunkt der Arbeit waren aber die Messungen an Wasserstoff für n = 3, bei denen zusätzlich Balmer-alpha-Fluoreszenz im Sichtbaren zur Detektion eingesetzt werden konnte. Bei elektrischen Feldern bis 200 V/cm wurden Stark-Spektren für drei verschiedene Polarisationszustände der Laserstrahlung aufgenommen. Als Ergebnis konnte jeweils ein Paar isolierter Stark-Komponenten in den Spektren identifiziert werden, dessen gut messbarer Frequenzabstand durch Vergleich mit theoretischen Werten die Bestimmung der elektrischen Feldstärke ermöglicht.
A method for electric field measurements that observes the Stark spectra of the low excited levels n = 2 and n = 3 of atomic hydrogen has been explored in this work. As advantage these levels can be excited Doppler-free from the ground state by a single laser and the highly resolved Stark spectra are easy to understand and to be calculated. Good sensitivity of electric field measurements is achieved with specially designed solid state laser systems, which provide tuneable pulsed UV radiation with a high pulse peak-power and a narrow bandwidth needed for Doppler-free two-photon excitation. Using hydrogen and deuterium the Stark spectra of the n = 2 level are detected as optogalvanic signal. For three different cases of laser polarization the n = 3 spectra of hydrogen are measured simultaneously with optogalvanic and laser induced Balmer alpha fluorescence detection. Electric fields down to 200 V/cm can be determined from the Stark spectra of n = 2 level, while the spectra of n = 3 level enable measurements of electric fields as small as 50 V/cm in each of the three cases of laser polarization.

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15

Glass, Fenton John, and f. glass@fz-juelich de. "Tomographic Visible Spectroscopy of Plasma Emissivity and Ion Temperatures." The Australian National University. Research School of Physical Sciences and Engineering, 2004. http://thesis.anu.edu.au./public/adt-ANU20051028.002110.

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Extending the use of Doppler spectroscopy as an important plasma diagnostic -- by developing a multi-channel system capable of tomography -- is the foundation of this thesis. A system which can simultaneously measure the emissivity, temperature and flow velocity of plasma ions has been installed, calibrated and operated on the H-1NF heliac, yielding comprehensive and interesting results. The measurements are time-resolved, made from a large range of viewing positions and, using scalar tomographic inversion methods, can be unfolded to give two-dimensional images of ion emissivity and temperature. The flow velocity profiles, while not inverted, nevertheless lead to a greater understanding of the plasma behaviour.¶ Fifty-five lens-coupled optical fibres, mounted on a large rotatable stainless steel ring, encircle the plasma poloidally and transport light to a multi-channel Fourier-transform spectrometer. This `coherence-imaging' spectrometer employs an electro-optically modulated birefringent crystal plate to monitor the coherence of an isolated spectral line. Measurement of the intensity, fringe visibility and phase of the resulting interferogram leads to values for the emissivity, ion temperature and flow velocity. Using a multi-anode photomultiplier assembly, allows the time-resolved detection of all optical channels simultaneously.¶ The system has been fully calibrated, including a measurement of the spatial response of each line-of-sight. The calibration procedure accounts for the relative channel sensitivities, the response of the line filter and the removal of detector cross-talk. In situ light sources are installed provide routine and accurate relative intensity calibration of the system.¶ Methods of tomography provide the unfolding of the measured plasma parameters to construct two-dimensional images of ion temperature and emissivity. Methods of inversion include the iterative ART routine -- using projection data gathered with the light-collecting optics rotated to different viewing positions -- and linear composition of Fourier-Bessel basis functions -- with the data obtained from a single unrotated viewing position. ART reconstructions of the emissivity are performed without the need for a priori information while those of the ion temperature are computed using regularising functions to help stabilise the inversion.¶ This new system -- named ToMOSS for Tomographic Modulated Optical Solid-state Spectrometer -- enables a more detailed study of various plasma phenomena observed in H-1NF. Among other results, this thesis presents the first tomographic reconstructions of emissivity and temperature fluctuations associated with a large-scale coherent instability.

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Thapa, Rajesh. "Doppler-free spectroscopy of acetylene in near infrared spectral region inside photonic band gap fiber." Manhattan, Kan. : Kansas State University, 2005. http://hdl.handle.net/2097/133.

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Schulze-Hartung, Tim [Verfasser], and Thomas [Akademischer Betreuer] Henning. "Searching and Characterising Exoplanets using Astrometry and Doppler Spectroscopy / Tim Schulze-Hartung ; Betreuer: Thomas Henning." Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1177040840/34.

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18

Kemp, Helen Rochelle. "Sensitive sub-doppler gas phase nonlinear laser spectroscopy for hyperfine structure analysis and trace analyte detection /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2002. http://wwwlib.umi.com/cr/ucsd/fullcit?p3036948.

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19

Mickadeit, Fritz Karl Matthew. "Sensitive doppler-free high-resolution spectroscopy based on laser wave mixing for hyperfine structure analysis and trace-concentration detection /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2001. http://wwwlib.umi.com/cr/ucsd/fullcit?p9993990.

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20

Jordan, Judith Elena [Verfasser], and Alban [Akademischer Betreuer] Kellerbauer. "High-resolution Doppler laser spectroscopy of the laser cooling candidate La‾ / Judith Elena Jordan ; Betreuer: Alban Kellerbauer." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180608895/34.

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21

Blackman, David Rhys. "Kinetic-hydrodynamic modelling of short-pulse Doppler-shift spectroscopy experiments, and resistive filamentation of fast-electron transport." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/18765/.

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Three pump-3ω-probe Doppler-shift spectroscopy experiments are presented along with both 1D radiation-hydrodynamics modelling (HYADES) and 1D three-stage modelling process involving: HYADES radiation-hydrodynamics pre-pulse calculations; EPOCH kinetic particle-in-cell main-pulse calculation initialised from HYADES result; followed by hydrodynamic calculations, initialised from EPOCH result, of the evolution after the main-pulse. These investigations are aimed at exploring the formation of shocks at the front surface of targets after interaction with an ultra-short (30 fs), ultra-intense (10^18 W/cm^2 ) laser pulse. To this end a 3ω-probe is delayed then reflected from a 3ω critical surface on the front surface to obtain a temporal profile of the velocity of this surface. Two investigations use identical polished crown glass targets, but are performed with lasers systems with different contrast ratios (10^5 and 10^7 ). HYADES simulations match experimental results for the high contrast experiments except at early times. HYADES simulations of low contrast experiments do not agree. The three-step modelling process shows good agreement with experimental results in both cases, though with some adjustment to the pre-plasma scale-length for the low contrast case. The third Doppler-spectroscopy experiment uses a low density (over-dense) foam target with identical setup to high-contrast case described. Experimental results show a similar magnitude Doppler-shift evolution as in low-contrast case. HYADES simulations show similarities to experimental results but not overall trend. The three-step modelling process shows that the experimental response may be due to post-soliton formation as a result of SRS or photon acceleration plasma instabilities. This is supported by an additional 2D EPOCH simulation. A fourth theoretical investigation is presented into the transport of fast electrons produced 10^19−20 W/cm^2 laser pulses using the hybrid code ZEPHYROS. A low resistivity (< 5 µωm) at low temperatures (1 eV) is found to be of critical importance to suppressing filamentation of electron beams through low-Z targets.

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22

Häggblad, Erik. "In vivo diffuse reflectance spectroscopy of human tissue : from point measurements to imaging /." Linköping : Department of Biomedical Engineering, Linköpings universitet, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15191.

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Menmuir, Sheena. "Visible spectroscopic diagnostics : application and development in fusion plasmas." Doctoral thesis, Stockholm : Fysik, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4541.

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Zhang, Jingdong, and 張敬東. "Development of optimized deconvoluted coincidence doppler broadening spectroscopy and deep level transient spectroscopies with applicationsto various semiconductor materials." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38279010.

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Zhang, Jingdong. "Development of optimized deconvoluted coincidence doppler broadening spectroscopy and deep level transient spectroscopies with applications to various semiconductor materials." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38279010.

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Jones, Myles. "Optical imaging spectroscopy and laser doppler flowmetry in rodent barrel cortex : the hemodynamic response to whisker stimulation and hypercapnia." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251371.

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Chen, Sophia Lee. "Two-Photon Direct Frequency Comb Spectroscopy of Rubidium." Oberlin College Honors Theses / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1337650567.

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Kurt, Mustafa. "Time Resolved Spectroscopy Of Laser Induced Air Plasma." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608985/index.pdf.

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The laser beam interaction with matter and the plasma generation have been studied for many years. In some applications what is really important is to understand the composition and the temporal evolution of the species in the interested medium. In this thesis, time resolved optical spectroscopy was employed to understand the evolution of the plasma which is produced by interaction of Infrared (1.064 µ
m) laser beam with air. In this thesis, a new technique is suggested to analyze the time evolution of laser induced breakdown spectroscopy. The suggested method and the instrumentation of the setup are tested with a single gas (He). After the tests, we analyzed time sequence spectra of Laser Induced Air Breakdown. The suggested method is based on triggering the laser and the spectrometer at different time and applying the spectrometer trigger time by adding the time delay (&
#916
t) between them by using the pulse generator. The results show that the decay rates are slowing down microseconds after the excitation of the plasma. The results of the time-resolved measurements of the line spectra show that different component of the air has different decay rate, and lifetime. The lifetime of helium is 20 µ
s, and the decay start 5 µ
s after the initiation of plasma. Air has 12 µ
s lifetime, and the decay start 3 µ
s after the initiation of the plasma. Also, the decay rate and the lifetime depend on the state. We also calculate Doppler velocity for different component and different emission states. Doppler velocities show that the component which has great mass has small velocity, the component which has small mass has high velocity.

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Amiryan, Arevik. "Formation of narrow optical resonances in thin atomic vapor layers of Cs, Rb, K and applications." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCK028/document.

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Cette thèse présente l'étude de l'interaction de lumière cohérente avec une couche sub-longueur d'onde de vapeur alcaline atomique confinée en nano-cellule et applications pour la formation de résonances optiques étroites.Nous développons un modèle théorique décrivant l'interaction résonante de lumière laser avec la couche mince de vapeur alcaline en présence d'un champ magnétique. Nous montrons qu'en raison d'un régime transitoire d'interaction, seuls les atomes lents contribuent au signal et leur spectre de transmission est essentiellement sans effet Doppler. La nature des spectres obtenus fait de la spectroscopie de transmission, en nano-cellule, une technique pratique pour l'étude de transitions très rapprochées et l'évolution de leur comportement dans un champ magnétique. Des expériences réalisées pour des champs magnétiques jusqu'à 7000 G montrent un excellent accord entre théorie et expérience.Nous explorons aussi la rotation Faraday du plan de polarisation de la lumière lors de sa propagation dans la couche mince atomique. Bien que l'angle de rotation soit très faible, nous observons que les résonances des spectres de rotation Faraday sont plus étroites que celles de transmission. Enfin, nous étudions de nouvelles possibilités pour former des résonances optiques étroites et montrons qu'un traitement par deuxième dérivée des spectres de transmission donne le meilleur rétrécissement de raies parmi toutes les méthodes étudiées dans cette thèse
This thesis presents the study of coherent light interaction with a sub-wavelength atomic alkali vapor layer confined in a nano-cell and applications for the formation of narrow optical resonances.We develop a theoretical model describing the resonant interaction of the laser light with the thin alkali vapor layer in the presence of an external static magnetic field. We show that due to a transient regime of interaction, only slow atoms contribute to the signal and their transmission spectrum is essentially Doppler-free. The nature of the obtained spectra makes the transmission spectroscopy from a nano-cell a convenient technique to perform studies of closely-spaced atomic transitions and investigate their behavior in magnetic fields. Experimental realizations for magnetic field up to 7000~G show an excellent agreement between theory and experiment.We also explore the Faraday rotation of the plane polarization of light with the propagation through the thin atomic slab. We see that despite a small angle of rotation, Faraday rotation spectra exhibit resonances narrower than that for transmission. At last, we investigate new possibilities to form narrow optical resonances in nano-cells and show that second derivation processing of transmission spectra yields the strongest line narrowing among all methods studied in this thesis

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Gatenby, Simon David. "A stereodynamical study of the H+Nâ†2O reaction." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301421.

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Antonsson, Johan. "On optical methods for intracerebral measurements during stereotactic and functional neurosurgery : Experimental studies." Doctoral thesis, Linköping : Linköping University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8081.

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Neto, Ibrahim El Chamaa. "IMPLANTACAO DE UM SISTEMA DE DIAGNOSTICOS POR ESPECTROSCOPIA E MEDIDA DE TEMPERATURA IONICA NO TBR-1." Universidade de São Paulo, 1992. http://www.teses.usp.br/teses/disponiveis/43/43131/tde-11052015-152545/.

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Um sistema de diagnóstico por espectroscopia no visível foi implantado no tokamak TBR-I. O diagnóstico consiste de um espectrógrafo (do tipo Czerny-Turner), um sistema de acoplamento óptico e um detetor multicanal (MCP). O diagnóstico foi usado para observar e identificar impurezas presentes no plasma do TBR-I. As principais impurezas observadas foram oxigênio (O-II) e nitrogênio (N-II). Foi feito um estudo no alargamento das linhas do hidrogênio e dos íons para se obter a temperatura a partir do efeito Doppler. As intensidades das linhas espectrais foram observadas de descarga em descarga.
A visible spectroscopic diagnostic was implemented on TBR-I tokamak. The diagnostic system consist of a 1,5 m spectrograph (Czerny-Turner type), an optical coupling system and a microchannel plate (MCP) detector. The diagnostic system was used to examine and document the impurity content of the plasma in TBR-I. The main impurities discovered were oxygen (O-II) and nitrogen (N-II). Line broadening experiments were performed on hydrogen and ions to obtain the temperatures using Doppler broadening effects. The intensities of the spectral lines were measured on a shot to shot basis.

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33

Gigl, Thomas [Verfasser], Christoph [Akademischer Betreuer] Hugenschmidt, Christoph [Gutachter] Hugenschmidt, and Günther [Gutachter] Dollinger. "New Brightness Enhanced Positron Microbeam for Spatially Resolved Doppler Broadening Spectroscopy at NEPOMUC / Thomas Gigl ; Gutachter: Christoph Hugenschmidt, Günther Dollinger ; Betreuer: Christoph Hugenschmidt." München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1198402172/34.

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Reiner, Markus [Verfasser], Christoph [Akademischer Betreuer] [Gutachter] Hugenschmidt, and Johannes [Gutachter] Barth. "Point Defects in MnSi and YBCO Studied by Doppler Broadening Spectroscopy Using a Positron Beam / Markus Reiner. Betreuer: Christoph Hugenschmidt. Gutachter: Christoph Hugenschmidt ; Johannes Barth." München : Universitätsbibliothek der TU München, 2015. http://d-nb.info/110493373X/34.

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35

Mariano, Leandro. "Estudo da distribuição de momento de elétrons ligados por correlação ângulo-energia da radiação de aniquilação elétron-pósitron." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-26012011-154606/.

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Neste trabalho foi medido o alargamento Doppler de uma aniquilação elétron pósitron com o uso de um filtro angular. O Filtro angular reduz, substancialmente, a detecção de fótons provenientes de aniquilações de elétrons com baixo momento, enfatizando, desta forma, a contribuição de aniquilações com elétrons fortemente ligados. Foram medidos os espectros de coincidência para os ângulos de corte de 0,28°, 0,42° e 1.2°. Os resultados obtidos mostram que, conforme se aumenta o ângulo de corte, há uma redução das aniquilações com elétrons de valência em proporção muito maior do que para elétrons fortemente ligados. Foi determinada a transmissibilidade do filtro em função do ângulo entre as direções de emissão dos gamas, levando em conta todos os elementos do arranjo experimental para cada ângulo crítico, assim como a distribuição espacial da atividade da fonte radioativa. Um modelo simples foi utilizado para estimar teoricamente a dependência da dispersão da energia em função do ângulo de corte. Este modelo permitiu calcular o alargamento Doppler da radiação de aniquilação elétron pósitron. Os resultados obtidos mostram um bom acordo com os dados experimentais. Geralmente, estudos de aniquilação de pósitrons com elétrons fortemente ligados dependem de uma modelagem detalhada do espectro de coincidência, ou da medida dos fótons provenientes da aniquilação em coincidência com elétrons Auger. O filtro angular, desenvolvido neste trabalho se coloca como uma boa alternativa a estes métodos.
This work reports the measurement of the Doppler broadening of the electron-positron annihilation radiation using an angular filter. The angular filter substantially reduces the number of detected gamma-rays from positron annihilation with low momentum electrons, therefore emphasizing the contribution of bound electron. Four coincidence measurements of the emitted gamma-rays were done with arrangements corresponding to critical angles of 0.28°, 0.42°, 1.2°. The obtained results show that the relative intensity of annihilation with valence electrons decreases as the critical angle increases. The filter transmissibility as a function of the angle between the two gamma-rays emission directions was determined taking into account all the elements of the experimental arrangement for every critical angle as well as the spatial distribution of the source activity. A simple model was used to theoretically estimate the dependence of the energy dispersion on the critical angle. The model allows us to calculate the Doppler broadening of the electron-positron annihilation radiation, and the obtained results show good agreement with the experimental data. Usually, the study of positrons annihilation with inner electrons requires good detectors\' energy resolution and depends on either sophisticated modeling and statistical analysis of the coincidence spectra or the measurement of the annihilation gamma-rays in coincidence with Auger electrons. The use of the angular filter developed in this work is a good alternative to those procedures.

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Choo, Hui C. "Peripheral blood flow changes in response to post-exercise cold water immersion." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2014. https://ro.ecu.edu.au/theses/1012.

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A reduction in body temperature is considered to be the primary mechanism by which cold water immersion (CWI) enhances short-term (h) recovery and improves exercise capacity in the heat. However, improvement in exercise performance may be optimised at a given cooling magnitude. Water temperature and immersion duration influence the magnitude of cooling in the core body, muscle and skin. Given the role of blood flow in convective heat flux, substrate delivery and metabolic waste clearance, it is important to understand the influence of different water temperatures on compartmental distribution of limb blood flow during CWI. Therefore, the purpose of this study was to compare blood flow changes in the common femoral artery, vastus lateralis muscle, and thigh skin induced by 5 min of post-exercise water immersion at 8°C, 14°C, 35°C or passive rest. In a randomised manner, nine recreationally active men performed exhaustive cycling in a climate control chamber (32.8 ± 0.4°C and 32 ± 5%rh), followed by 5 min of water immersion at 8.6 ± 0.2°C (WI8), 14.6 ± 0.3°C (WI14), 35.0 ± 0.4°C (WI35) or passive rest (CON). The exercise task involved 25 min of cycling at a power output equivalent to first ventilatory threshold, followed by high-intensity intermittent cycling (30 s at 90% of peak power output to 30 s at 70 W). Measurement of blood flow in thigh skin (laser Doppler flowmetry), vastus lateralis muscle (near infrared spectroscopy), and common femoral artery (Doppler ultrasound), heart rate, mean arterial pressure, skin, muscle, rectal, and mean body temperatures were obtained prior to exercise and up to 60 min post-immersion. Both WI14 and WI8 reduced mean body, calf and thigh skin, and muscle temperatures, compared with WI35 and CON (p0.05). Relative to pre-immersion, differences were observed in the magnitude of reduction between skin, muscle, and common femoral blood flow. Decreases in muscle and skin blood flow were similar (p>0.05), but to a lesser extent when compared with femoral blood flow (p Therefore, 5 min of CWI at 8°C and 14°C effectively reduced temperatures, when compared with CON and WI35. Although WI8 was more effective than WI14 in reducing mean body temperature, there was no influence on the decreases in skin, muscle and femoral blood flow. Furthermore, WI8 did not result in significant reduction in muscle blood flow compared to WI35, despite significant muscle cooling. Given that mean arterial blood pressure was elevated, it is possible hydrostatic effects during WI35, coupled with shivering thermogenesis during WI8 confounded extent of muscle blood flow reduction in the present study. As such, influence of hydrostatic pressure per se on peripheral blood flow cannot be ruled out although blood flow changes were similar between WI35 and CON. Additionally, current findings indicate unknown vascular beds, other than measured sites in the vastus lateralis muscle and thigh skin, contribute to overall changes in the limb blood flow. It appears that vasoconstriction in skin and muscle vasculatures are associated with the interaction between suppressed vasodilatory substances (e.g. nitric oxide) and altered baroreflex mediated sympathetic nerve activity. However, underlying mechanisms warrant further investigation.

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Pikart, Philip [Verfasser], Christoph Pascal [Akademischer Betreuer] Hugenschmidt, and Peter [Akademischer Betreuer] Müller-Buschbaum. "Advances in Coincident Doppler Broadening Spectroscopy: Element Selective Studies on Metallic Nanolayers with Monoenergetic Positrons / Philip Pikart. Gutachter: Peter Müller-Buschbaum ; Christoph Pascal Hugenschmidt. Betreuer: Christoph Pascal Hugenschmidt." München : Universitätsbibliothek der TU München, 2012. http://d-nb.info/1024567427/34.

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Oliveira, Maria Ines Novis de. "Localização e estadiamento local do adenocarcinoma prostático por ressonância magnética com estudo perfusional e espectroscopia: correlação com resultados histopatológicos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/5/5151/tde-24112010-170852/.

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O adenocarcinoma prostático (CaP) é o tumor que ocupa a segunda posição em incidência e em mortalidade dentre as neoplasias malignas masculinas, tendo aumentado a detecção de tumores em estágios precoces da sua história natural nas últimas décadas, frequentemente pequenos e pouco agressivos. A definição clínica mais aceita de tumor de baixo risco foi proposta por DAmico e consiste em PSA 10 ng/ml, Gleason 6 e não ser palpável ou não acometer mais de um lobo prostático no toque retal. A localização do tumor na próstata, bem como o seu estadiamento local através da detecção de extensão extracapsular (EEC) e/ou invasão de vesículas seminais (IVS) têm importância fundamental na opção e adequação terapêuticas. O objetivo deste trabalho foi avaliar a ultrassonografia transretal (USTR), a ultrassonografia com Doppler de amplitude (USDA), a ressonância magnética (RM), a espectroscopia de prótons por RM (RMS) e a RM dinâmica com contraste endovenoso (RMD) na localização tumoral e estadiamento local do CaP de baixo risco, em comparação com resultados anatomopatológicos. Este foi um estudo prospectivo realizado entre os anos de 2005 e 2009, que avaliou 35 pacientes por RM, RMS e RMD, dos quais 26 foram também submetidos a USTR e USDA. Após a prostatectomia radical, 16 (45,7%) destes pacientes apresentaram doença confinada à próstata, em 11 (31,4%) detectou-se margem cirúrgica positiva e 8 (28,9%) exibiram doença extraprostática. Sensibilidade, especificidade, valores preditivos positivo e negativo (VPP e VPN) e acurácia na localização do CaP foram de 53,1%; 48,3%; 63,4%; 37,8% e 51,3% para USTR; 70,4%; 36,2%; 65,1%; 42,0% e 57,7% para USDA; 71,5%; 58,9%; 76,6%; 52,4% e 67,1% para RM; 70,4%; 58,7%; 78,4%; 48,2% e 66,7% para RMS; 67,2%; 65,7%; 79,3%; 50.6% e 66,7% para RMD, respectivamente. Sensibilidade, especificidade, VPP, VPN e acurácia na detecção de EEC foram de 33,3%; 92,0%; 14,3%; 97,2% e 89,7% para USTR e 50,0%; 77,6%; 13,7%; 95,6% e 75,7% para RM, respectivamente. Para detecção de IVS esses valores foram de 66,7%; 85,7%; 22,2%; 97,7% e 84,6% para USTR e 40,0%; 83,1%; 15,4%; 94,7% e 80,0% para RM. Embora preliminares, estes resultados sugerem que os métodos avaliados apresentam baixa concordância na localização e estadiamento local do CaP de baixo risco
Prostate cancer is the second most common tumor and cause of deaths among men neoplasms, with increased detection of tumors at earlier stages in its natural history in the recent decades, often of small size and low agressiveness. The most accepted classification for low-risk prostate cancer was proposed by DAmico and is defined as PSA 10 ng/ml, Gleason score 6 and being undetected or limited to one lobe on digital rectal exam. Tumor location within the prostate as well as its local staging, which consists in extracapsular extension (ECE) and seminal vesicle invasion (SVI) detection, are of extreme importance in treatment choice and planning. The purpose of this study was to evaluate transrectal ultrasound (TRUS), amplitude Doppler ultrasound (ADUS), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS) and dynamic contrast-enhanced magnetic resonance imaging (DMRI) in localizing and locally staging low-risk prostate cancer, in comparison with surgical histopathology. This was a prospective study realized from the year of 2005 to 2009, which evaluated 35 patients by MRI, MRS and DMRI, 26 of whom were also submitted to TRUS and ADUS. After radical prostatectomy, 16 (45.7%) of these patients had pathologically proved organ confined disease, 11 (31.4%) had positive surgical margin and 8 (28.9%) had extraprostatic disease. Sensitivity, specificity, positive and negative predictive values (PPV and NPV) and accuracy values for localizing low risk prostate cancer were: 53.1%, 48.3%, 63.4%, 37.8% and 51.3% for TRUS; 70.4%, 36.2%, 65.1%, 42.0% and 57.7% for ADUS; 71.5%, 58.9%, 76.6%, 52.4% and 67.1% for MRI; 70.4%, 58.7%, 78.4%, 48.2% and 66.7% for MRS; 67.2%, 65.7%, 79.3%, 50.6% and 66.7% for DMRI, respectively. Sensitivity, specificity, PPV, NPV and accuracy values for detecting ECE were: 33.3%, 92%, 14.3%, 97.2% and 89.7% for TRUS and 50.0%, 77.6%, 13.7%, 95.6% and 75.7% for MRI, respectively. For detecting SVI, these values were of 66.7%, 85.7%, 22.2%, 97.7% and 84.6% for TRUS and 40.0%, 83.1%, 15.4%, 94.7% and 80.0% for MRI. Although preliminary, our results suggest that imaging modalities have low agreement in localizing and locally staging low-risk prostate cancer

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Elhami, Esmat. "STUDIES OF LOW-LYING STATES IN 94ZR EXCITED WITH THE INELASTIC NEUTRON SCATTERING REACTION." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_diss/624.

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The aim of nuclear structure studies is to observe and describe the structures and associated symmetries in nuclei, which in turn help us in understanding the nature of nucleon-nucleon interactions in a nucleus as a many-body quantum system. The protons and neutrons as constituents of a nucleus and their interactions are responsible for nuclear properties. The evolution of nuclear structure as a function of valence nucleon number, i.e., the number of nucleons beyond a magic number, can be inferred from the experimental level scheme and transition rates. In particular, the studies of low-lying, low-spin excited states in stable nuclei provide valuable information on the interplay of valence neutrons and protons in nuclear structure. The decay scheme and knowledge of transition strengths in the low-lying states become a benchmark for testing theoretical model predictions and understanding the underlying microscopic foundations of nuclear structure. Along with the experimental techniques, theoretical models have been developed to explain and describe the observed nuclear properties, e.g., shell model, Fermi-gas model, optical and liquid-drop models, and several “collective” models. 94/40Zr50 nucleus with 2 protons and 4 neutrons above the shell closures of the 88/38Sr50 core nucleus is considered as a nearly spherical nucleus. Such nuclei present a vibrational structure; surface vibration of the nucleus about a spherical shape. In addition to the symmetric excitations, in which proton and neutron oscillations are in phase, there are another class of excitations in which the wave function is not fully symmetric with respect to the exchange of protons and neutrons. These states are so called mixed-symmetry (MS) states. Such excitations have been observed in the N= 52 neighboring isotones. In this study, the low-lying structure of 94/40Zr has been studied with the (n, n'ƴ) reaction at the University of Kentucky and Triangle Universities Nuclear Laboratories (TUNL) facilities, to identify symmetric and MS excitations in this nucleus. A decay scheme has been established based on excitation function and coincidence measurements. Branching ratios, multipole mixing ratios, and spin assignments have been determined from angular distribution measurements at En= 2.3, 2.8, and 3.5 MeV. Lifetimes of levels up to 3.4 MeV were measured by the Doppler-shift attenuation method (DSAM), and for many transitions reduced transition probabilities were determined. The experimental results were used for the identification of collective symmetric and mixed-symmetric (MS) multiphonon excitations. The 2+/2 state at 1671.4 keV has been identified as the lowest MS state in 94Zr; B(M1; 2+/ms → 2+/1 ) = 0.31(3) μ2/N. This state has an anomalous decay behavior, i.e., B(E2; 2+/ ms → 0+/1 ) = 7.8(7) W.u., which is unusually large compared to the B(E2; 2+/1 → 0+/1 ) = 4.9(3) W.u. More anomalies were identified in the states above the 2+/ms state. For example, the 4+/2 state at 2330 keV decays strongly to the 2+/1 state, B(E2; 4+/2 → 2+/1 ) = 20+3/−2 W.u., compared to the 4+/1 state at 1469 keV, B(E2; 4+/1 → 2+/1 ) = 0.878(23) W.u. The experimental results revealed additional interesting and unusual properties of the low-lying states in 94Zr. Shell model calculations were performed with the Oxbash code, using the Vlow k interaction. Also, the IBM-2 predictions in the vibrational limit were compared with the experimental results. The results from neither of these nuclear models were in good agreement with the observed transition strengths, e.g., the B(E2; 2+/ms → 0+/1 ) value. These observations may indicate that the contributions of valence nucleons in the low-lying excited states of 94Zr differ from what has been perscribed by the shell model and the IBM-2 model. The effects of the Z = 40 and N = 56 subshell closures should be also considered. In a simple interpretation, the excited states are classified in two distinct categories, i.e., those populating the 2+/2 state and those decaying to the 2+/1 state. This approach suggests that in 94Zr the low-lying states may be related to two-configurations coexistence.

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Sun, Yu-Ping. "Spontaneous and stimulated X-ray Raman scattering." Doctoral thesis, KTH, Teoretisk kemi (stängd 20110512), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32859.

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The present thesis is devoted to theoretical studies of resonant X-ray scattering and propagation of strong X-ray pulses. In the first part of the thesis the nuclear dynamics of different molecules is studied using resonant X-ray Raman and resonant Auger scattering techniques. We show that the shortening of the scattering duration by the detuning results in a purification of the Raman spectra from overtones and soft vibrational modes. The simulations are in a good agreement with measurements, performed at the MAX-II and the Swiss Light Source with vibrational resolution. We explain why the scattering to the ground state nicely displays the vibrational structure of liquid acetone in contrast to excited final state. Theory of resonant X-ray scattering by liquids is developed. We show that, contrary to aqueous acetone, the environmental broadening in pure liquid acetone is twice smaller than the broadening by soft vibrational modes significantly populated at room temperature. Similar to acetone, the "elastic" band of X-ray Raman spectra of molecular oxygen is strongly affected by the Thomson scattering. The Raman spectrum demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the oxygen atoms separate. It is found that the vibrational scattering anisotropy caused by the interference of the "inelastic" Thomson and resonant scattering channels in O2. A new spin selection rule is established in inelastic X-ray Raman spectra of O2. It is shown that the breakdown of the symmetry selection rule based on the parity of the core hole, as the core hole and excited electron swap parity. Multimode calculations explain the two thresholds of formation of the resonant Auger spectra of the ethene molecule by the double-edge structure of absorption spectrum caused by the out-of- and in-plane modes. We predict the rotational Doppler effect and related broadening of X-ray photoelectron and resonant Auger spectra, which has the same magnitude as its counterpart-the translational Doppler effect. The second part of the thesis explores the interaction of the medium with strong X-ray free-electron laser (XFEL) fields. We perform simulations of nonlinear propagation of femtosecond XFEL pulses in atomic vapors by solving coupled Maxwell's and density matrix equations. We show that self-seeded stimulated X-ray Raman scattering strongly influences the temporal and spectral structure of the XFEL pulse. The generation of Stokes and four-wave mixing fields starts from the seed field created during pulse propagation due to the formation of extensive ringing pattern with long spectral tail. We demonstrate a compression into the attosecond region and a slowdown of the XFEL pulse up to two orders of magnitude. In the course of pulse propagation, the Auger yield is strongly suppressed due to the competitive channel of stimulated emission. We predict a strong X-ray fluorescence from the two-core-hole states of Ne created in the course of the two-photon X-ray absorption.
QC 20110426

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Ho, King-fung. "Some studies in deconvoluting Coincidence Doppler Broadening spectra /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B23621953.

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Ho, King-fung, and 何競豐. "Some studies in deconvoluting Coincidence Doppler Broadening spectra." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B29773726.

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Kochukhov, Oleg. "Magnetic and Chemical Structures in Stellar Atmospheres." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3383.

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Foltynowicz, Aleksandra. "Fiber-laser-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-22269.

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Noise-immune cavity-enhanced optical heterodyne molecular spectro-metry (NICE-OHMS) is one of the most sensitive laser-based absorption techniques. The high sensitivity of NICE-OHMS is obtained by a unique combination of cavity enhancement (for increased interaction length with a sample) with frequency modulation spectrometry (for reduction of noise). Moreover, sub-Doppler detection is possible due to the presence of high intensity counter-propagating waves inside an external resonator, which provides an excellent spectral selectivity. The high sensitivity and selectivity make NICE-OHMS particularly suitable for trace gas detection. Despite this, the technique has so far not been often used for practical applications due to its technical complexity, originating primarily from the requirement of an active stabilization of the laser frequency to a cavity mode. The main aim of the work presented in this thesis has been to develop a simpler and more robust NICE-OHMS instrumentation without compro-mising the high sensitivity and selectivity of the technique. A compact NICE-OHMS setup based on a fiber laser and a fiber-coupled electro-optic modulator has been constructed. The main advantage of the fiber laser is its narrow free-running linewidth, which significantly simplifies the frequency stabilization procedure. It has been demonstrated, using acetylene and carbon dioxide as pilot species, that the system is capable of detecting relative absorption down to 3 × 10-9 on a Doppler-broadened transition, and sub-Doppler optical phase shift down to 1.6 × 10-10, the latter corresponding to a detection limit of 1 × 10-12 atm of C2H2. Moreover, the potential of dual frequency modulation dispersion spectrometry (DFM-DS), an integral part of NICE-OHMS, for concentration measurements has been assessed. This thesis contributes also to the theoretical description of Doppler-broadened and sub-Doppler NICE-OHMS signals, as well as DFM-DS signals. It has been shown that the concentration of an analyte can be deduced from a Doppler-broadened NICE-OHMS signal detected at an arbitrary and unknown detection phase, provided that a fit of the theoretical lineshape to the experimental data is performed. The influence of optical saturation on Doppler-broadened NICE-OHMS signals has been described theoretically and demonstrated experimentally. In particular, it has been shown that the Doppler-broadened dispersion signal is unaffected by optical saturation in the Doppler limit. An expression for the sub-Doppler optical phase shift, valid for high degrees of saturation, has been derived and verified experimentally up to degrees of saturation of 100.

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Crepp, Justin R., Jonathan Crass, David King, Andrew Bechter, Eric Bechter, Ryan Ketterer, Robert Reynolds, et al. "iLocater: a diffraction-limited Doppler spectrometer for the Large Binocular Telescope." SPIE-INT SOC OPTICAL ENGINEERING, 2016. http://hdl.handle.net/10150/622805.

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We are developing a stable and precise spectrograph for the Large Binocular Telescope (LBT) named "iLocater." The instrument comprises three principal components: a cross-dispersed echelle spectrograph that operates in the YJ-bands (0.97-1.30 mu m), a fiber-injection acquisition camera system, and a wavelength calibration unit. iLocater will deliver high spectral resolution (R similar to 150,000-240,000) measurements that permit novel studies of stellar and substellar objects in the solar neighborhood including extrasolar planets. Unlike previous planet-finding instruments, which are seeing-limited, iLocater operates at the diffraction limit and uses single mode fibers to eliminate the effects of modal noise entirely. By receiving starlight from two 8.4m diameter telescopes that each use "extreme" adaptive optics (AO), iLocater shows promise to overcome the limitations that prevent existing instruments from generating sub-meter-per-second radial velocity (RV) precision. Although optimized for the characterization of low-mass planets using the Doppler technique, iLocater will also advance areas of research that involve crowded fields, line-blanketing, and weak absorption lines.

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Valley, John Francis. "Nonlinear optical experiments in sodium vapor and comparison with Doppler-broadened two-level-atom theory." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184930.

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Two spectral regions of gain exist for a weak probe beam propagating through a medium of two-level-atoms pumped by a strong near-resonance field. Experimentally a cw ring-dye laser is used to explore this gain at the Na D₂ resonance in a vapor. Plane-wave calculations of probe-gain spectra which include the Doppler broadening inherent in a vapor agree well with experimental spectra obtained with a Fabry-Perot interferometer. Such two-beam-coupling gain might have applications as optical pre- or power amplifiers. The gain is also the primary step in four-wave-mixing. Mixing of the pump and sideband which experiences gain produces the medium polarization from which the fourth-wave arises. For phase-matched propagation the fourth-wave, which is at a frequency that experiences little or negative probe-gain (i.e., absorption), grows at nearly the same rate as the primary sideband. Together the two sidebands extract far more than twice as much energy from the pump than does the primary sideband acting alone. Experimentally four-wave-mixing which arises from noise at the gain-sideband-frequency is sometimes accompanied by conical emission at the fourth-wave sideband. Since this sideband is also seen on axis the explanation cannot be simply phase-matching. Simulations which include the full transverse nature of the experiment are currently running on a CRAY supercomputer. These simulations indicate that the radial variation of the medium index of refraction is responsible for conical emission.

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Zheng, Ximeng. "Fiber post-processing and atomic spectroscopy for the development of atomic-vapour photonic microcell." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0031/document.

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Cette thèse concerne la spectroscopie atomique pour le développement de microcellules photoniques à base de vapeur atomique alcaline (PMC). Le travail est motivé par reproduire les performances remarquables obtenues dans les domaines des références de fréquences et de l’optique cohérente en environnement laboratoire et à les transférer dans des dispositifs très compacts et autonomes accessibles à une communauté scientifique plus large ou à un marché commercial. Dans notre cas, ces futurs composants seront basés sur une fibre à cristal photonique à coeur creux (HC-PCF) remplie d'un matériau en phase gazeuse pour former la PMC et se distingue par une longueur d'interaction ultra longue associée à des dimensions modales transverses micrométriques. Cependant, cette échelle micrométrique du coeur creux de la fibre contenant les atomes soulève plusieurs défis techniques et scientifiques. Parmi les défis techniques, nous énumérons le développement d'un processus efficace pour le chargement d'atomes dans une telle fibre optique, la suppression ou l'atténuation de la réactivité physio-chimique des atomes (c'est-à-dire le rubidium) avec la surface interne silice entourant le coeur de la fibre, etc... En parallèle, le rapport large surface / volume du coeur de la fibre soulève des questions comme la dynamique de relaxation de la cohérence et la nature et l'effet de l'interaction atome-surface. Ainsi, les travaux de thèse reposent sur l’utilisation de revêtements spécifiques de la surface interne du coeur de la fibre avec différents matériaux pour atténuer ces réactions physico-chimiques, sur l'amincissement des larges coeurs creux des HC-PCF Kagomé à couplage inhibé et sur une technique de soudure qui garantit de faibles pertes d’insertion et l’absence de réactivité avec les atomes. Parallèlement, la thèse rapporte un ensemble d'expériences de spectroscopie pour évaluer la dynamique de relaxation des atomes à l'intérieur des HC-PCF et l’observation de nouvelles transparences sous-Doppler
This thesis reported on atomic spectroscopy for the development of alkaline atomic vapor photonic microcell (PMC). The work is motivated by reproducing the outstanding laboratory environment based performances achieved in the fields of frequency standard and coherent optics in highly compact and stand-alone devices that can be accessible to a wider scientific community or to a commercial market. In our case these future devices will be based a Hollow-core photonic crystal fiber (HC-PCF) filled with a gas phase material to form a PMC, and outstands with an ultra-long long interaction length and micrometric modal area. However, the micrometric scale of the fiber core harboring the atoms raises several technical and scientific challenges. Among the technical challenges, we list the development of efficient process for atom loading inside long hollow fiber with small core diameter, the suppression or mitigation of physio-chemical reactivity of the atoms (i.e. Rubidium) with the fiber core inner-surface silica etc. In parallel, the large surface-to-volume ratio of the fiber-core raises questions like the coherence relaxation dynamics and the nature and effect of the atom-surface interaction. The thesis reports on fiber-core inner surface coating with different materials to mitigate the physio-chemical reactions of the confined atoms with the surface, on tapering large core inhibited coupling Kagome HC-PCF, and splicing technique that ensures low splice loss and no atomic reactivity during the splicing process. In parallel, the thesis reports on a set of spectroscopy experiments to assess the relaxation dynamics of atoms inside HC-PCF and to report on novel sub-Doppler transparencies

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Smirni, Salvatore. "Nonlinear dynamics of microcirculation and energy metabolism for the prediction of cardiovascular risk." Thesis, University of Dundee, 2018. https://discovery.dundee.ac.uk/en/studentTheses/c551cbef-6f00-48ef-b753-ad76ac93daf4.

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The peripheral skin microcirculation reflects the overall health status of the cardiovascular system and can be examined non-invasively by laser methods to assess early cardiovascular disease (CVD) risk factors, i.e. oxidative stress and endothelial dysfunction. Examples of methods used for this task are the laser Doppler flowmetry (LDF) and laser fluorescence spectroscopy (LFS), which respectively allow tracing blood flow and the amounts of the coenzyme NAD(P)H (nicotamide adenine dinucleotide) that is involved in the cellular production of ATP (adenosine triphosphate) energy. In this work, these methods were combined with iontophoresis and PORH (post-occlusive reactive hyperaemia) reactive tests to assess skin microvascular function and oxidative stress in mice and human subjects. The main focus of the research was exploring the nonlinear dynamics of skin LDF and NAD(P)H time series by processing the signals with the wavelet transform analysis. The study of nonlinear fluctuations of the microcirculation and cell energy metabolism allows detecting dynamic oscillators reflecting the activity of microvascular factors (i.e. endothelial cells, smooth muscle cells, sympathetic nerves) and specific patterns of mitochondrial or glycolytic ATP production. Monitoring these dynamic factors is powerful for the prediction of general vascular/metabolic health conditions, and can help the study of the mechanisms at the basis of the rhythmic fluctuations of micro-vessels diameter (vasomotion). In this thesis, the microvascular and metabolic dynamic biomarkers were characterised in-vivo in a mouse model affected by oxidative stress and a human cohort of smokers. Data comparison, respectively, with results from control mice and non-smokers, revealed significant differences suggesting the eligibility of these markers as predictors of risk associated with oxidative stress and smoke. Moreover, a relevant link between microvascular and metabolic oscillators was observed during vasomotion induced by α-adrenergic (in mice) or PORH (in humans) stimulations, suggesting a possible role of cellular Ca²⁺oscillations of metabolic origin as drivers of vasomotion which is a theory poorly explored in literature. As future perspective, further exploration of these promising nonlinear biomarkers is required in the presence of risk factors different from smoke or oxidative stress and during vasomotion induced by stimuli different from PORH or α-adrenergic reactive challenges, to obtain a full picture on the use of these factors as predictors of risk and their role in the regulation of vasomotion.

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Nyström, Josefina. "Multivariate non-invasive measurements of skin disorders." Doctoral thesis, Umeå University, Chemistry, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-865.

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Abstract:

The present thesis proposes new methods for obtaining objective and accurate diagnoses in modern healthcare. Non-invasive techniques have been used to examine or diagnose three different medical conditions, namely neuropathy among diabetics, radiotherapy induced erythema (skin redness) among breast cancer patients and diagnoses of cutaneous malignant melanoma. The techniques used were Near-InfraRed spectroscopy (NIR), Multi Frequency Bio Impedance Analysis of whole body (MFBIA-body), Laser Doppler Imaging (LDI) and Digital Colour Photography (DCP).

The neuropathy for diabetics was studied in papers I and II. The first study was performed on diabetics and control subjects of both genders. A separation was seen between males and females and therefore the data had to be divided in order to obtain good models. NIR spectroscopy was shown to be a viable technique for measuring neuropathy once the division according to gender was made. The second study on diabetics, where MFBIA-body was added to the analysis, was performed on males exclusively. Principal component analysis showed that healthy reference subjects tend to separate from diabetics. Also, diabetics with severe neuropathy separate from persons less affected.

The preliminary study presented in paper III was performed on breast cancer patients in order to investigate if NIR, LDI and DCP were able to detect radiotherapy induced erythema. The promising results in the preliminary study motivated a new and larger study. This study, presented in papers IV and V, intended to investigate the measurement techniques further but also to examine the effect that two different skin lotions, Essex and Aloe vera have on the development of erythema. The Wilcoxon signed rank sum test showed that DCP and NIR could detect erythema, which is developed during one week of radiation treatment. LDI was able to detect erythema developed during two weeks of treatment. None of the techniques could detect any differences between the two lotions regarding the development of erythema.

The use of NIR to diagnose cutaneous malignant melanoma is presented as unpublished results in this thesis. This study gave promising but inconclusive results. NIR could be of interest for future development of instrumentation for diagnosis of skin cancer.

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50

謙太, 土居, and Kenta Doi. "Spectroscopy study of hydrogen particle reflection at helium-induced fuzzy tungsten surface." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13071680/?lang=0, 2018. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13071680/?lang=0.

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Abstract:

本研究では、低粒子エネルギー領域における金属表面からの反射水素原子を水素原子バルマーアルファ（Hα）発光ドップラー分光計測によって検出する実験系を構築し、ヘリウムによるタングステン表面の微細構造化が水素粒子反射特性に与える影響を調査した。表面構造を持たないタングステンと比較して、Fuzz構造をもつタングステン試料では200 - 300 eVの入射粒子エネルギー領域にて粒子反射係数が1/2程度まで減少することが明らかになった。
In this study, the author developed a measurement technique to detect hydrogen atoms reflected from a metal surface based upon the Doppler-spectroscopy of hydrogen Balmer-(Hα) emission. The developed measurement technique is a promising method to investigate the hydrogen particle reflection properties in low incident particle energy range, which has been considered difficult. The author applied the developed method into practice to clarify the effects of helium (He) induced tungsten (W) surface nanostructure upon the low energy hydrogen particle reflection. A W-fuzz sample was found to reduce the particle reflection coefficient by 1/2 of the flat reference W surface in low incident particle energy range of 200-300 eV.
博士(工学)
Doctor of Philosophy in Engineering
同志社大学
Doshisha University

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Dissertations / Theses on the topic 'Doppler-spectroscopy'

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