Увійти

Готові списки джерел за темами / Spontaneous emission of Hydrogen atoms

Добірка наукової літератури з теми "Spontaneous emission of Hydrogen atoms"

Автор: Grafiati

Опубліковано: 7 липня 2024

Оновлено: 7 липня 2024

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Spontaneous emission of Hydrogen atoms".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Зміст

Статті в журналах
Дисертації
Книги
Частини книг
Тези доповідей конференцій

Статті в журналах з теми "Spontaneous emission of Hydrogen atoms":

1

Cao, Chang-qi, Xiao-wei Fu, and Hui Cao. "Non-Markovian theory of relativistic electric-dipole spontaneous emission of hydrogen-like atoms." Journal of Optics B: Quantum and Semiclassical Optics 7, no. 2 (January 7, 2005): 43–53. http://dx.doi.org/10.1088/1464-4266/7/2/003.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Архипов, Р. М., М. В. Архипов, И. Бабушкин, А. В. Пахомов та Н. Н. Розанов. "Генерация аттосекундного импульса на основе коллективного спонтанного излучения слоя трехуровневых атомов, возбуждаемых парой униполярных импульсов". Журнал технической физики 128, № 11 (2020): 1723. http://dx.doi.org/10.21883/os.2020.11.50176.182-20.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Recently, for the generation of extremely short pulses, a method was proposed for coherent control of the polarization of a medium, based on the excitation of atomic polarization oscillations and their subsequent arrest using a pair of ultra short pulses. The so-called stopped pulse of polarization of the medium, which appears in the interval between its excitation and de-excitation, can be a source of an extremely short radiation pulse. In this paper, the indicated possibility of generating an isolated attosecond ultraviolet pulse in a three-level resonant medium, the parameters of which correspond to a hydrogen atom excited by a pair of unipolar X-ray pulses, is considered theoretically. In this case, the generation mechanism is "antenna", that is, it is caused by the collective spontaneous emission of pre-phased atoms in the absence of a noticeable decay of their free polarization. Key words: collective spontaneous emission, coherent control of atomic polarization, attosecond pulses, unipolar pulses, X-ray pulses, hydrogen atom.

3

Druett, M. K., and V. V. Zharkova. "HYDRO2GEN: Non-thermal hydrogen Balmer and Paschen emission in solar flares generated by electron beams." Astronomy & Astrophysics 610 (February 2018): A68. http://dx.doi.org/10.1051/0004-6361/201731053.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Aim. Sharp rises of hard X-ray (HXR) emission accompanied by Hα line profiles with strong red-shifts up to 4 Å from the central wavelength, often observed at the onset of flares with the Specola Solare Ticinese Telescope (STT) and the Swedish Solar Telescope (SST), are not fully explained by existing radiative models. Moreover, observations of white light (WL) and Balmer continuum emission with the Interface Region Imaging Spectrograph (IRISH) reveal strong co-temporal enhancements and are often nearly co-spatial with HXR emission. These effects indicate a fast effective source of excitation and ionisation of hydrogen atoms in flaring atmospheres associated with HXR emission. In this paper, we investigate electron beams as the agents accounting for the observed hydrogen line and continuum emission. Methods. Flaring atmospheres are considered to be produced by a 1D hydrodynamic response to the injection of an electron beam defining their kinetic temperatures, densities, and macro velocities. We simulated a radiative response in these atmospheres using a fully non-local thermodynamic equilibrium (NLTE) approach for a 5-level plus continuum hydrogen atom model, considering its excitation and ionisation by spontaneous, external, and internal diffusive radiation and by inelastic collisions with thermal and beam electrons. Simultaneous steady-state and integral radiative transfer equations in all optically thick transitions (Lyman and Balmer series) were solved iteratively for all the transitions to define their source functions with the relative accuracy of 10−5. The solutions of the radiative transfer equations were found using the L2 approximation. Resulting intensities of hydrogen line and continuum emission were also calculated for Balmer and Paschen series. Results. We find that inelastic collisions with beam electrons strongly increase excitation and ionisation of hydrogen atoms from the chromosphere to photosphere. This leads to an increase in Lyman continuum radiation, which has high optical thickness, and after the beam is off it governs hydrogen ionisation and leads to the long lasting orders of magnitude enhancement of emission in Balmer and Paschen continua. The ratio of Balmer-to-other-continuum head intensities are found to be correlated with the initial flux of the beam. The height distribution of contribution functions for Paschen continuum emission indicate a close correlation with the observations of heights of WL and HXR emission reported for limb flares. This process also leads to a strong increase of wing emission (Stark’s wings) in Balmer and Paschen lines, which is superimposed on large red-shifted enhancements of Hα-Hγ line emission resulting from a downward motion by hydrodynamic shocks. The simulated line profiles are shown to fit closely the observations for various flaring events.

4

Cao, Chang-qi, Xiao-wei Fu, and Hui Cao. "Non-Markovian study of the relativistic magnetic-dipole spontaneous emission process of hydrogen-like atoms." Journal of Physics B: Atomic, Molecular and Optical Physics 39, no. 8 (April 10, 2006): 2071–85. http://dx.doi.org/10.1088/0953-4075/39/8/022.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Shimoda, Jiro, and J. Martin Laming. "Radiative transfer of hydrogen lines from supernova remnant shock waves: contributions of 2s-state hydrogen atoms." Monthly Notices of the Royal Astronomical Society 485, no. 4 (March 16, 2019): 5453–67. http://dx.doi.org/10.1093/mnras/stz758.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract Radiative transfer in hydrogen lines in supernova remnant (SNR) shock waves is studied taking into account the population of the hydrogen atom 2s-state. Measurements of Balmer line emission, especially of H α, are often relied on to derive physical conditions in the SNR shock. On the other hand, Lyman series photons, especially Ly β, are mostly absorbed by upstream hydrogen atoms. As a result, atoms are excited to the 3p state, and then emit H α by the spontaneous transition from 3p to 2s. Thus, the nature of H α depends on how many Ly β photons are converted to H α photons. Moreover, the Balmer lines can be scattered by the 2s-state hydrogen atoms, which are excited not only by collisional excitation but also by the Lyman–Balmer conversion. It is shown for example that the H α photons are scattered if the shock propagates into an H i cloud with a density of ∼30 cm−3 and a size of ∼1 pc. We find that the line profile of H α becomes asymmetric resulting from the difference between line centre frequencies among the transitions from 3s to 2p, from 3p to 2s, and from 3d to 2p. We also find that the broad-to-narrow ratio of H α, which is often used to estimate the ion-electron temperature equilibrium, varies at most ≃ 10 per cent depending on the ionization degree of the upstream medium because of incomplete conversion of Lyman lines to Balmer lines.

6

Jahanpanah, J. "The forming mechanism of spontaneous emission noise flux radiated from hydrogen-like atoms by means of vibrational Hamiltonian." AIP Advances 11, no. 3 (March 1, 2021): 035203. http://dx.doi.org/10.1063/5.0036017.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Druett, M. K., and V. V. Zharkova. "Non-thermal hydrogen Lyman line and continuum emission in solar flares generated by electron beams." Astronomy & Astrophysics 623 (February 26, 2019): A20. http://dx.doi.org/10.1051/0004-6361/201732427.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Aims. Hydrogen Lyman continuum emission is greatly enhanced in the impulsive kernels of solar flares, with observations of Lyman lines showing impulsive brightening and both red and blue wing asymmetries, based on the images with low spatial resolution. A spate of proposed instruments will study Lyman emission in more detail from bright, impulsive flare kernels. In support of new instrumentation we aim to apply an improved interpretation of Lyman emission with the hydrodynamic radiative code, HYDRO2GEN, which has already successfully explained Hα emission with large redshifts and sources of white light emission in solar flares. The simulations can interpret the existing observations and propose observations in the forthcoming missions. Methods. A flaring atmosphere is considered to be produced by a 1D hydrodynamic response to injection of an electron beam, defining depth variations of electron and ion kinetic temperatures, densities, and macro-velocities. Radiative responses in this flaring atmosphere affected by the beams with different parameters are simulated using a fully non-local thermodynamic equilibrium (NLTE) approach for a five-level plus continuum model hydrogen atom with excitation and ionisation by spontaneous, external, and internal diffusive radiation, and by inelastic collisions with thermal and beam electrons. Integral radiative transfer equations for all optically thick transitions are solved using the L2 approximation simultaneously with steady state equations. Results. During a beam injection in the impulsive phase there is a large increase of collisional ionisation and excitation by non-thermal electrons that strongly (by orders of magnitude) increases excitation and the ionisation degree of hydrogen atoms from all atomic levels. These non-thermal collisions combined with plasma heating caused by beam electrons lead to an increase in Lyman line and continuum radiation, which is highly optically thick. During a beam injection phase the Lyman continuum emission is greatly enhanced in a large range of wavelengths resulting in a flattened distribution of Lyman continuum over wavelengths. After the beam is switched off, Lyman continuum emission, because of its large opacity, sustains, for a very long time, the high ionisation degree of the flaring plasma gained during the beam injection. This leads to a long enhancement of hydrogen ionisation, occurrence of white light flares, and an increase of Lyman line emission in cores and wings, whose shapes are moved closer to those from complete redistribution (CRD) in frequencies, and away from the partial ones (PRD) derived in the non-flaring atmospheres. In addition, Lyman line profiles can reflect macro-motions of a flaring atmosphere caused by downward hydrodynamic shocks produced in response to the beam injection reflected in the enhancements of Ly-line red wing emission. These redshifted Ly-line profiles are often followed by the enhancement of Ly-line blue wing emission caused by the chromospheric evaporation. The ratio of the integrated intensities in the Lyα and Lyβ lines is lower for more powerful flares and agrees with reported values from observations, except in the impulsive phase in flaring kernels which were not resolved in previous observations, in which the ratio is even lower. These results can help observers to design the future observations in Lyman lines and continuum emission in flaring atmospheres.

8

Ungor, Ditta, Gyöngyi Gombár, Ádám Juhász, Gergely F. Samu, and Edit Csapó. "Promising Bioactivity of Vitamin B1-Au Nanocluster: Structure, Enhanced Antioxidant Behavior, and Serum Protein Interaction." Antioxidants 12, no. 4 (April 3, 2023): 874. http://dx.doi.org/10.3390/antiox12040874.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

In the current work, we first present a simple synthesis method for the preparation of novel Vitamin-B1-stabilized few-atomic gold nanoclusters with few atomic layers. The formed nanostructure contains ca. eight Au atoms and shows intensive blue emissions at 450 nm. The absolute quantum yield is 3%. The average lifetime is in the nanosecond range and three main components are separated and assigned to the metal–metal and ligand–metal charge transfers. Based on the structural characterization, the formed clusters contain Au in zero oxidation state, and Vitamin B1 stabilizes the metal cores via the coordination of pyrimidine-N. The antioxidant property of the Au nanoclusters is more prominent than that of the pure Vitamin B1, which is confirmed by two different colorimetric assays. For the investigation into their potential bioactivity, interactions with bovine serum albumin were carried out and quantified. The determined stoichiometry indicates a self-catalyzed binding, which is almost the same value based on the fluorometric and calorimetric measurements. The calculated thermodynamic parameters verify the spontaneous bond of the clusters along the protein chain by hydrogen bonds and electrostatic interactions.

9

Tana, R., and Z. Ficek. "Entangling two atoms via spontaneous emission." Journal of Optics B: Quantum and Semiclassical Optics 6, no. 3 (March 1, 2004): S90—S97. http://dx.doi.org/10.1088/1464-4266/6/3/015.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Żakowicz, W. "Spontaneous Emission by Atoms in Simple Environments." Acta Physica Polonica A 101, no. 1 (January 2002): 119–31. http://dx.doi.org/10.12693/aphyspola.101.119.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Більше джерел

Дисертації з теми "Spontaneous emission of Hydrogen atoms":

1

Cayayan, Lyndon Mark D. "Collective Quantum Jumps of Rydberg Atoms Undergoing Two-Channel Spontaneous Emission." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1470410030.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Federico, Maxime. "Spatio-temporal description of single photons : from cavity production to local detection." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCK013.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Ce travail fournit une analyse des propriétés spatio-temporelles d'états à un photon. En commençant par une quantification directement réalisée en espace position, nous démontrons que deux formulations différentes de la théorie sont équivalentes : elles prédisent les mêmes résultats. L'équivalence est formulée sous forme d'un isomorphisme de leurs espaces de Hilbert respectifs. On utilise par la suite cette construction en espace position pour étudier la propagation des photons décrit par des impulsions. Nous démontrons que la dynamique de n'importe quel état du champ électromagnétique quantique est alors donnée par l'évolution temporelle de la représentation de l'état, telle que décrite par les équations de Maxwell classiques. Nous construisons également un modèle de détection locale de photons en utilisant l'opérateur densité d'énergie. Ce modèle nous permet de démontrer la non localité de tout état à un photon grâce à la propriété d'antilocalité de l'opérateur fréquence Ω=c(-Δ)^{1/2}. Nous caractérisons ensuite cette non localité pour un état à un photon produit par l'émission spontanée d'un atome d'Hydrogène et montrons que la décroissance de sa densité d'énergie se comporte asymptotiquement comme pour des distances r loin de l'atome. Enfin, nous nous interessons à la production de photons en cavités pour laquelle nous démontrons au travers d'un argument topologique que, dans la limite adiabatique, l'approximation de l'onde tournante (rotating wave approximation) est justifiée et permet donc la production de photons très proches de photons uniques parfaits. Nous construisons aussi, comme résultat préliminaire, un modèle heuristique utilisant des modes quasinormaux pour décrire la procution de photons dans des cavités ouvertes
This work provides an analysis of spatio-temporal properties of single-photon states. Starting with a direct quantization in position space representation, we show that two different formulations are equivalent, i.e., they give the same quantum theory. The equivalence is formulated in terms of isomorphisms of their respective Hilbert space of states. We then use this construction in position space to study the propagation of photons in terms of pulses and we show that the dynamics of any state of the quantum electromagnetic field is given by the classical Maxwell equations for the classical pulse onto which the photons are defined. We also construct a model for local detection of photons using the energy density operator. This model allows us to show the nonlocality of all single-photon states using the anti-local property of the frequency operator Ω=c(-Δ)^{1/2}. We then characterize this nonlocal property for a single-photon state spontaneously emitted by a Hydrogen atom and we show a radial decay of its energy density of 1/r^6 in the asymptotic limit of large distances r from the atom. Finally, we consider the production of photons in cavities where we show through topological arguments that in the adiabatic limit, the rotating wave approximation is justified and thus the photons produced with these techniques can be very close to perfect single photons. We also construct as a preliminary result a heuristic model using quasinormal modes to describe the production of photons inside leaky cavities

3

Lees, Eitan Jacob. "Suppression of Collective Quantum Jumps of Rydberg Atoms due to Collective Spontaneous Emission from Atoms in Free Space." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1438276591.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Bosch, Aguilera Manel. "Coherence and relaxation of an optically-driven bosonic quantum gas : experiments with ultracold ytterbium atoms." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS174.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Dans ce travail de thèse, je présente une série d'études expérimentales réalisées avec des gaz d'ytterbium ultrafroids excités sur différentes transitions optiques. L'ytterbium appartient à la famille des atomes dits alcalino-terreux. Ces atomes possèdent une structure électronique riche, avec une transition d’horloge exempte d’émission spontanée et une transition étroite d'intercombinaison. Avec des expériences de spectroscopie sur la transition d'horloge dans des réseaux optiques profonds, je montre notre capacité à exciter cette transition de manière cohérente pendant de longues périodes. Ce contrôle est ensuite utilisé dans un premier temps en tant qu'outil pour mesurer les longueurs de diffusion des états impliqués dans la transition d'horloge et ensuite, pour préparer un petit système quantique ouvert, où la dissipation prend la forme de pertes à deux corps. En branchant ce couplage adiabatiquement, on observe une forte suppression de ces pertes, ce qui est interprété comme une signature de l'effet Zénon quantique. J'utilise finalement ce transfert cohérent pour étudier la dynamique de relaxation d'un condensat de Bose-Einstein. Enfin, je développe une étude sur un système ouvert avec des interactions fortes. Ici, on induit artificiellement de la dissipation sous la forme d'émission spontanée en utilisant la transition d'intercombinaison, et j'étudie comment la cohérence spatiale d'un superfluide dans un réseau optique est détruite. Ces expériences révèlent que la présence d'interactions fortes protège partiellement une cohérence résiduelle et entraîne un développement non-triviale de la décohérence, révélant ainsi l'émergence d'un canal de relaxation subdiffusif
In this thesis I report on a series of experimental studies performed with ultracold ytterbium gases driven in different optical transitions. Ytterbium belongs to the family of the so-called alkaline-earth-like atoms, which feature a rich electronic structure, with an optical clock transition free of spontaneous emission, and a narrow intercombination transition, making them very appealing for metrological and quantum simulation proposals. By performing spectroscopy on the clock transition, I prove on a first set of experiments in deep optical lattices our ability to drive this transition coherently for long times. This coherent control is then used for different studies. First, as tool to measure the scattering lengths of the states involved in the clock transition. Then, to prepare a small open quantum system, where dissipation arises in the form of two-body losses. By enabling the coupling adiabatically, we observe a strong suppression of these losses, which is interpreted as a signature of the quantum Zeno effect. I ultimately use the coherent driving to study the relaxation dynamics of a dissipative bulk Bose-Einstein condensate. Finally, I elaborate an investigation on a strongly-interacting open system. Dissipation is artificially induced in the form of spontaneous emission using the intercombination transition. Here, I study in which manner spontaneous emission destroys the spatial coherence of a superfluid in an optical lattice. These experiments reveal that the presence of strong interactions partially protects a residual amount of coherence and makes decoherence develop in a non-trivial manner, unveiling the emergence of a subdiffusive relaxation channel

5

Dickheuer, Sven Oliver [Verfasser], Oleksandr [Gutachter] Marchuk, and Uwe [Gutachter] Czarnetzki. "The Balmer lines emission of fast hydrogen atoms at the plasma-solid interface in a low density plasma / Sven Oliver Dickheuer ; Gutachter: Oleksandr Marchuk, Uwe Czarnetzki ; Fakultät für Physik und Astronomie." Bochum : Ruhr-Universität Bochum, 2020. http://d-nb.info/1204258244/34.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Baudouin, Quentin. "Lumière dans des vapeurs atomiques opaques : piégeage radiatif, laser aléatoire et vols de Lévy." Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00952969.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

L'interaction matière-lumière dans des milieux opaques donne lieu à des phénomènes collectifs nécessitant le couplage d'équations atomiques et d'une équation de transport. Le piégeage de la lumière dans un système atomique multi-niveaux sera étudié expérimentalement dans une vapeur froide et théoriquement avec le couplage des paramètres atomiques à une équation de diffusion. Ensuite, du gain sera ajouté dans ce nuage d'atomes froids multi niveaux. Nous montrerons théoriquement qu'un seuil laser existe dans ce type de système combinant gain et diffusion et qu'expérimentalement le gain Raman associé à de la diffusion sur une raie résonante a permis l'observation d'un laser aléatoire à atomes froids. La validité de l'équation de diffusion nécessite une non redistribution en fréquence et donc des atomes suffisamment froids pour s'affranchir de l'effet Doppler. Finalement nous étudierons le transport dans une vapeur atomique chaude (20°C-180°C) opaque. L'effet Doppler invalide la loi de Beer-Lambert pour la longueur des pas des photons entre des diffusions qui suivent alors une statistique de Lévy.

7

Galand, Marina. "Transport des protons dans l'ionosphère aurorale." Phd thesis, Université Joseph Fourier (Grenoble), 1996. http://tel.archives-ouvertes.fr/tel-00724355.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Les électrons et les protons suprathermiques, issus du soleil et précipitant dans l'atmosphère des hautes latitudes, constituent une source d'énergie de l'ionosphère terrestre. Ces particules interagissent avec le gaz thermique ambiant par collisions. L'équation de Boltzmann, fournissant les flux de particules en altitude, énergie et angle d'attaque, permet une description des plus complètes du transport de ces particules. Nous la redémontrons dans le cas dissipatif, le plus général, et nous proposons une résolution originale des équations de transport des protons et des atomes d 'hydrogène, équations couplées via les réactions de changement de charge. Cette résolution, fondée sur l'introduction de forces dissipatives pour décrire la dégradation énergétique des particules précipitant, permet la prise en compte des redistributions angulaires, d'origine collisionnelle ou magnétique, jusqu'alors négligées. Pourtant, leur effet a été observé, depuis le sol, sur les émissions des atomes d 'hydrogène, comme en témoigne la composante, décalée vers le rouge, du profil Doppler selon le zénith magnétique. La résolution adoptée ici est validée par comparaison avec un autre modèle, dans le cas classique sans redistribution angulaire. L'influence de l'effet de miroir magnétique est discutée: cet effet ne semble pas pouvoir expliquer, à lui seul, le décalage vers le rouge observé. La redistribution angulaire collisionnelle doit jouer un rôle significatif. Enfin, une comparaison de notre modèle avec les données de la fusée Proton 1 est proposée.

8

Suraud, Marie-Gabrielle. "Etude par spectrométrie X (10 [angström] [inférieur ou égal à] [lamda] [inférieur ou égal à] 100 [angström]) de l'échange de charge lors de collision à basse énergie, entre un ion multichargé et une cible neutre." Grenoble 1, 1988. http://www.theses.fr/1988GRE10038.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Mesures des valeurs absolues des sections efficaces d'emission de rayons x, dont on deduit les valeurs absolues des sections efficaces de capture, pour les systemes c**(6+)-he,h::(2), n**(7+)-he,h::(2), o**(8+)-he,h::(c). Pour les projectiles a 2 electrons dans l'etat metastable 1s2s **(3)s, l'echange de charge peut s'accompagner de l'excitation de l'electron "2s" de l'ion incident vers des etats 1s2pnl **(3)p avec une probabilite variant suivant le systeme de collision, l'echange de charge simple restant preponderant dans tous les cas

Книги з теми "Spontaneous emission of Hydrogen atoms":

1

Ellam, Rob. 1. Identical outsides … different insides. Oxford University Press, 2016. http://dx.doi.org/10.1093/actrade/9780198723622.003.0001.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

‘Identical outsides … different insides’ describes the isotopes of hydrogen (protium, deuterium, tritium) and carbon (carbon-12, carbon-13, carbon-14). The isotopes exist due to an extra particle (neutron) or two in the element’s nucleus, which adds extra mass to the atom. Tritium and carbon-14 are both unstable and undergo radioactive decay. There are four types of radioactive decay: α, β, γ (alpha, beta, gamma), and spontaneous fission. Radioactive decay is the process whereby the nucleus of an unstable atom loses energy by emission of ionizing radiation. The rate of the radioactive decay is measured by the ‘half-life’—the time needed for half the radioactive isotopes of a substance to decay.

Частини книг з теми "Spontaneous emission of Hydrogen atoms":

1

Carmichael, Howard J. "Two-Level Atoms and Spontaneous Emission." In Statistical Methods in Quantum Optics 1, 29–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-662-03875-8_2.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Zakowicz, Wladyslaw, and A. Blędowski. "Spontaneous Emission by Atoms near a Dielectric Waveguide." In Quantum Field Theory Under the Influence of External Conditions, 267. Wiesbaden: Vieweg+Teubner Verlag, 1996. http://dx.doi.org/10.1007/978-3-663-01204-7_50.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Bonetti, R., C. Chiesa, A. Guglielmetti, and C. Migliorino. "Evidence of Spontaneous Emission of Oxygen Clusters from 228Th." In Clustering Phenomena in Atoms and Nuclei, 293. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-662-02827-8_30.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Ficek, Z., R. Tanaś, and S. Kielich. "Photon Antibunching in Spontaneous Emission from Two Nonidentical Atoms." In Coherence and Quantum Optics VI, 295–99. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0847-8_54.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Seke, Josip, and Wolfgang Herfort. "Deviations from Exponential Decay in the Spontaneous Emission by a Two-Level Hydrogenic Atom." In Coherence and Quantum Optics VI, 1059–63. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0847-8_192.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Seke, J. "On the Spontaneous Emission from Two-Level Atoms in a Damped Cavity." In Disequilibrium and Self-Organisation, 155–63. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4718-4_11.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Heinzen, D. J., J. J. Childs, C. R. Monroe, and M. S. Feld. "Enhanced and Suppressed Visible Spontaneous Emission by Atoms in a Concentric Optical Resonator." In Laser Spectroscopy VIII, 36–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-540-47973-4_9.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Brooker, Geoffrey. "Spontaneous emission of radiation." In Essays in Physics, 417–54. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198857242.003.0032.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

“Spontaneous emission of radiation” calculates the rate of spontaneous electric-dipole emission of a photon by an excited atom or molecule. The calculation proceeds by using basic quantum mechanics (i.e. not using the short cuts of Chapter 19); it uses quantum electrodynamics but is not, on that account, particularly difficult. A 2p–1s transition in hydrogen is used as exemplar; the radiation is elliptically polarized. The spectral line profile (lineshape function) is approximately Lorentzian, but has a high-frequency cut-off, needed to prevent the power radiated from diverging. A radiation-induced frequency shift is negligible. The width of the line profile agrees with the Einstein A-coefficient. A high-frequency cut-off is shown to apply similarly in the derivation of Golden Rule Number Two.

9

Parker, Eugene N. "Solar X-Ray Emission." In Spontaneous Current Sheets In Magnetic Fields, 328–66. Oxford University PressNew York, NY, 1994. http://dx.doi.org/10.1093/oso/9780195073713.003.0011.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract The curious optical emission spectrum of the solar corona puzzled spectroscopists for decades until it was suggested by Grotrian ( l 931, 1933, 1939) that the temperature is of the order of 106K. With this possibility in mind Edlen (1942a,b) was able to identify nineteen of the coronal lines (Lyot, 193:J) as arising from forbidden transitions of highly ionized atoms (e.g., Fex, f-exIv, NixIII, CaxII), clearly establishing an electron temperature of the general order of l06 K. Radio observations corroborated this result.

10

Akhmanov, S. A., and S. YU Nikitin. "The laser." In Physical Optics, 159–80. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780198517955.003.0010.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Abstract Quantum properties of atoms and Bohr’s postulates. Optical quanta. Spontaneous and stimulated emission in a quantum-mechanical system. The operational principle and design of a laser. The characteristics of laser radiation. The generation of ultra-short pulses.

Тези доповідей конференцій з теми "Spontaneous emission of Hydrogen atoms":

1

Heard, Dwayne E., and Jay B. Jeffries. "Laser-excited amplified spontaneous emission of atomic hydrogen in low pressure flames." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/oam.1991.tue1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Amplified spontaneous emission (ASE) has been observed at the Balmer α wavelength from two-photon excited 3S and 3D hydrogen atoms. ASE has several advantages for atom diagnostic measurements in reacting flows compared to resonance enhanced multiphoton ionization or laser-induced fluorescence (LIF). The ASE signal is collimated along the excitation laser beam, which simplifies optical alignment, reduces the necessary optical access, and increases the spectral brightness. These can be significant advantages in reacting flows and material processing plasmas where ion collection probes can alter the process and LIF measurement precision and detectivity is often limited by background optical emission. Simultaneous ASE and LIF measurements in a variety of collisional environments are discussed, which demonstrate the influence of gas collisions on the ASE signal. Bandwidth measurements of the ASE are demonstrated for single laser pulses.

2

Mahon, Christopher, Dwayne Heard, Michael Brown, Gregory Smith, and Jay Jeffries. "Laser-induced fluorescence and amplified spontaneous emission detection of hydrogen atoms in flames." In 34th Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-465.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Ficek, Z., and R. Tanas. "Entanglement of two atoms induced by spontaneous emission." In 2003 European Quantum Electronics Conference. EQEC 2003 (IEEE Cat No.03TH8665). IEEE, 2003. http://dx.doi.org/10.1109/eqec.2003.1314233.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

4

Clemens, James P., Levente Horvath, Barry C. Sanders, and Howard J. Carmichael. "Collective spontaneous emission from small assemblies of atoms." In SPIE's First International Symposium on Fluctuations and Noise, edited by Derek Abbott, Jeffrey H. Shapiro, and Yoshihisa Yamamoto. SPIE, 2003. http://dx.doi.org/10.1117/12.490148.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Gazazyan, Emil, Vigen Chaltykyan, and Alfred Gazazyan. "Coherent control of spontaneous emission in driven multilevel atoms." In International Conference on Laser Physics 2010, edited by Aram V. Papoyan. SPIE, 2010. http://dx.doi.org/10.1117/12.890509.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

6

Heinzen, D. J., J. J. Childs, and M. S. Feld. "Visible spontaneous emission by atoms in an optical resonator." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.mi5.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Recently, we observed enhancement and inhibition of visible spontaneous emission by atoms in a confocal resonator.1 In these experiments, the partial emission rate of the atom into the resonator modes is modified by a factor of 1/(1 − R), where R is the mirror reflectivity. The change in the total spontaneous emission rate is proportional to the solid angle ΔΩ subtended by the mirrors; the change was small (+1.6%, −0.5%) because ΔΩ ≈ 0.04 sr was small. Currently we are conducting experiments in which atoms are placed in a concentric resonator of large solid angle ΔΩ ≈ 3.6 sr and finesse of ~10. We estimate that a 30% decrease and 300% increase should be observable in the total spontaneous emission rate, when the resonator is tuned off or on-resonance, respectively. Results of this new experiment are presented. In addition to studying spontaneous processes, one can also consider the stimulated emission which occurs when a cavity field builds up which contains more than one photon. We have formulated a model which describes both the spontaneous and stimulated emission by the atom into the cavity and clarifies the relationship between enhanced spontaneous emission and stimulated emission.

7

Narducci, L. M., P. Ru, J. R. Tredicce, G. L. Oppo, and M. O. Scully. "Subnatural spontaneous emission spectra in driven atoms: the V-model." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.tur1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The coherent coupling of atomic levels under the action of driving electromagnetic fields is known to create unusual and interesting effects, such as the well-known population trapping phenomenon and subnatural line narrowing. In this paper we discuss two alternative configurations of three-level atoms, the cascade model and the inverted-V (lambda) model, in an effort to provide alternative options for experimental tests. In both cases we focus on the fluorescent emission spectrum of an atom driven by two resonant fields and on the absorption spectrum of a weak probe passing through a gas in such a driven system. Subnatural line narrowing can be obtained from the cascade system but not from the lambda system. The lambda system, however, is characterized by strong population trapping, so that it is not suitable for fluorescence studies (except out of resonance) because of its strongly reduced emission rate. The absorption spectrum of a weak probe displays gain features under high-field conditions which suggest that useful amplification of a probe or laser-like emission should be possible over appropriate frequency ranges. We give a physical interpretation of the origin of the gain and explain why that in the case of a lambda system, but not a cascade system, steady-state population inversion can be obtained between both excited states relative to the lowest state of the atom. We also discuss the effect of Doppler broadening on the predicted emission and absorption lineshapes.

8

Glauber, Roy J. "Cooperative Spontaneous Emission and Scattering of Light by Ensembles of Atoms." In Conference on Coherence and Quantum Optics. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/cqo.2007.ctuc1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Erdogan, T., K. G. Sullivan, and D. G. Hall. "Spontaneous emission from radiating atoms in cylindrically and spherically symmetric periodic structures." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.fee3.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

Recently there has been considerable interest in the concept of a manufactured structure exhibiting a "photonic band gap"—an energy band in the electromagnetic spectrum for which wave propagation is isotropically forbidden. Conventional treatments have employed a Bloch-wave approach to explore the spectral and directional nature of wave propagation in multi-dimensional, translationally invariant, Cartesian periodic structures. Utilizing a classical model, we directly treat the interaction of a radiating dipole with the fields supported by cylindrical and spherical Bragg structures. These novel structures, which are not translationally invariant, are capable of effectively confining light emitted from a central, but finite-sized, region. The size of this region depends on both source and structure characteristics, including the modulation and radial extent of the Bragg structure. We examine the radiative lifetime variations and resonance frequency shifts associated with particular idealizations of the structure and source. The results presented are of fundamental and practical interest owing to the unique geometry of the considered Bragg structures, which have recently been realized as semiconductor laser resonators in the form of cylindrical waveguide diffraction gratings.

10

Bochove, E. J., and P. W. Milonni. "Spontaneous and stimulated emission by atoms interacting with a phase conjugate mirror." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.wr4.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Анотація:

The properties of a phase conjugate mirror (PCM) interacting radiatively with other objects are investigated. The spontaneous emission rate of a two-level atom (TLA) is attributed to the dipole emission of the upper energy level into vacuum field modes incident on the front face of the PCM, the emission into vacuum modes transmitted from the rear port of the PCM, enhanced by a factor 1 + R (R = reflectivity), and the emission of a photon while the atom is in the lower level, accompanied by annihilation of two pump photons, weighted by a factor of R per emitted photon. These processes lead to an enhancement factor of 1 + R for the spontaneous decay rate and a steady state upper level occupation probability R/(2R + 2), both in agreement with solution of the Heisenberg equations of TLA operators.1 The momentum transfer is zero, and the steady state emission rate is A12R(R + 2)/(2R + 2) photons/s atom. The stimulated emission and absorption constants are enhanced in a similar way. Contrary to the case of a conventional mirror, the Lippman fringes are present only for coherent radiation states.