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1.
I. S. Osad’ko 《Journal of Experimental and Theoretical Physics》1999,89(3):513-524
A dynamic theory of two-photon correlators for a single impurity center developed recently by the author [I. S. Osad’ko, Zh.
éksp. Teor. Fiz. 113, 1606 (1998) [JETP 86, 875 (1998)] has been generalized to the case in which the center interacts with nonequilibrium two-level systems (TLSs)
in polymers and glasses. Quantum tunneling transitions in TLS manifest themselves as random jumps of a spectral line of an
impurity center. These jumps can be either spontaneous or light-induced. Interaction between the impurity center and many
nonequilibrium TLSs, which exist in polymers, results in a time dependence of the optical dephasing rate 1/T
2 of an impurity molecule, i.e., in spectral diffusion. This paper describes how the jumps of the spectral line manifest themselves
in the two-photon correlator, which can be measured in experiments.
Zh. éksp. Teor. Fiz. 116, 962–985 (September 1999) 相似文献
2.
V. Ch. Zhukovskii V. D. Krevchik M. B. Semenov Yu. G. Smirnov P. V. Krevchik S. A. Gubina 《Moscow University Physics Bulletin》2009,64(6):579-584
The effect of dissipative tunneling parameters on the spectral dependence of the probability of two-photon impurity absorption
in a quantum molecule is theoretically investigated. The effect of the tunnel barrier transparency on two-photon impurity
absorption in a quantum molecule is shown to manifest itself as a change in the width of energy levels of the virtual and
final states due to variations in such parameters of dissipative tunneling as temperature, photon-mode frequency, and the
constant of interaction with a heat bath. 相似文献
3.
The complex of optical investigations into the intrinsic (I) and resonant (R) two-photon absorption (TPA) inZnSiP
2 crystals of tetragonal modifications is performed by methods of amplitude laser-modulation spectroscopy. The ITPA of allowed-forbidden
type and the two Lorentz spectral lines associated with coherent resonant two-photon transitions through impurity states of
allowed-allowed type are found. The electron transverse relaxation time at the RTPA is determined, and the total absorption
cross section of laser-radiation photons emitted at electron transitions between the valence band v, the conduction band c,
and local centers that produce real states intermediate for the RTPA in the forbidden band is estimated.
M. P. Dragomanov National Pedagogical University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp.
36–43, February, 2000. 相似文献
4.
A pressed CuCl pellet is optically excited at 2 K using an excitation energy in the range from 1892 to 2843 meV, which is far below the bandgap. The steady-state population dynamics unambiguously indicates an unusual two-photon generation of ground-state excitons. At high-excitation levels, the observed spectra exhibit rich spectral features arising from electron-hole plasma and electron-hole droplets formation. This nonresonant two-photon excitation is presumably assisted by impurity bands due to grain boundaries and surfaces in this random semiconductor. 相似文献
5.
A two-photon impurity absorption coefficient of the “quantum dot — D(−)-center” complexes synthesized in a transparent dielectric matrix is calculated within the model of zero-radius potential.
The evolution of spectral dependence of the absorption coefficient of the nanoheterostructure based on semiconductor CdS
x
Se
1−x
glasses is studied versus the average quantum-dot radius. It is shown that the contribution of the two-photon impurity absorption
to the exited two-photon luminescence is fairly significant at a reasonable quantum-dot concentration.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 46–50, July, 2005. 相似文献
6.
E. A. DONLEY R. MARQUARDTT M. QUACK J. STOHNER I. THANOPULOS E.-U. WALLENBORN 《Molecular physics》2013,111(15):1275-1287
Results are reported on coherent monochromatic multiphoton excitation in many-level systems, which are representative for some of the basic mechanisms for atomic and molecular multiphoton processes. Numerical solutions are discussed that use the Floquet and quasi-resonant approximations in the framework of the URIMIR program package. The excitation schemes include direct three-photon excitation, two-photon excitation with diagonal coupling, Göppert-Mayer-type two-photon processes, multiphoton excitation with off-resonant inter-mediates, and practically irreversible coherent excitation into dense spectral structures. Several interesting phenomena are observed, such as nonlinear line shifts and broadenings of multi-photon resonances of relevance for multiphoton spectroscopy and almost constant intermediate population inversions, potentially useful for laser design. The accurate numerical results are compared with approximate solutions from perturbation theory, and with simple analytical solutions from Rabi-type formulae. 相似文献
7.
Zn–Se crystals are used to analyze prospects for application of two-photon confocal microscopy in the study of plane and volume interband and impurity luminescence in semiconductors. Such maps can be formed with a depth step and planar spatial resolution of several micrometers at distances of up to 1 mm from the surface. The method is used to detect luminescence-active inhomogeneities in crystals and study their structure and luminescence characteristics. Prospects for the application of the two-photon confocal microscopy in the study of direct-band-semiconductors and materials of the fourth group are discussed. 相似文献
8.
在离子速度成像的实验装置中,将波长为492~523 nm范围内的激光倍频,以经过倍频的激光作光源,将碘甲烷分子(CH3I)电离,获得了碘甲烷母体分子离子(CH3I+)在76 500~81 120 cm-1范围内的高分辨双光子电离光谱;介绍了CH3I的双光子电离机制,根据Rydberg公式和量子数亏损成功对实验所得到的CH3I+谱中的46个谱峰做了标识,并观察到了CH3I+谱中p,d,f系列的能级分裂。标识结果表明,在CH3I的双光子电离谱中除了可以观察到单光子电离谱的特征,还可以观察到在单光子电离中禁阻的f系列跃迁。 相似文献
9.
A review of recent results of studying the low-temperature dynamics of a disordered solid-state medium that were obtained
by the method of single molecule spectroscopy (SMS) is presented. The studies were carried out with the use of the new approach
of the statistical analysis of a large number of spectra of single molecules embedded into a medium under study as a microscopic
spectral probe. The measurements were performed in the range 2–7 K. The use of SMS allowed us to avoid the information losses
connected with the averaging over an ensemble of impurity molecules that is inherent in conventional spectral methods. For
the example of the system studied (amorphous polyisobutylene doped with molecules of tetra-tert-butylterrylene), it was shown experimentally that, at low temperatures, the spectra of single impurity molecules in disordered
media obey the Levy statistics. New microscopic information on the interaction of two-level systems and quasi-local low-frequency
vibrational modes of the matrix with impurity molecules in a disordered medium was obtained. 相似文献
10.
M. L. H. ter Heerdt S. A. Basun G. F. Imbusch W. M. Yen 《Journal of luminescence》2002,100(1-4):115-124
We have employed two-photon excitation to study the higher energy levels of Gd3+ ions in CaAl12O19 and we compare the results with those obtained using conventional UV excitation techniques. Under two-photon excitation, the luminescence intensity exhibits an unusual temporal behavior, a very long build-up followed by a decrease by orders of magnitude, ascribed to a recombination-assisted luminescence excitation mechanism assuming photo-ionization of Gd3+ ions and trapping of free electrons on deep traps.
We also find that the two-photon excitation spectra contain an additional broadening contribution which can be attributed to homogeneous broadening of excitation levels caused by excited state absorption into the conduction band. We believe that this may be a general phenomenon whenever participating photons produce ionization of impurity ions from metastable excited states. The phenomenon can manifest itself also in two-photon ionization spectral hole burning and in up-conversion processes (in the latter case, the homogeneous broadening can be caused by an intra-ion excited-state absorption). 相似文献
11.
We experimentally demonstrate two-photon absorption with broadband down-converted light (squeezed vacuum). Although incoherent and exhibiting the statistics of a thermal noise, broadband down-converted light can induce two-photon absorption with the same sharp temporal behavior as femtosecond pulses, while exhibiting the high spectral resolution of the narrow band pump laser. Using pulse-shaping methods, we coherently control two-photon absorption in rubidium, demonstrating spectral and temporal resolutions that are 3-5 orders of magnitude below the actual bandwidth and temporal duration of the light itself. Such properties can be exploited in various applications such as spread-spectrum optical communications, tomography, and nonlinear microscopy. 相似文献
12.
主要报道天然FeS2黄铁矿,(以下称FeS2(P))的室温、低温的远红外反射光谱和透射光谱,并对其光谱结构及物理起源作了较详细的讨论。通过我们的研究发现:室温反射光谱低频端等离子体反射边和样品中所含的PbS(方铅矿)杂技存在密切的联系。我们以FeS2(P)矿物单晶和PbS矿物单晶的反射光谱作为基谱对不同样品的实验结果进行了复合,所得出的x值不仅可以反映PbS杂质的含量,而且间接地与贵金属元素Au等存在较好的正相关性。这对于研究矿物的成因等有
关键词: 相似文献
13.
I. S. Osad’ko 《Journal of Experimental and Theoretical Physics》1998,86(5):875-887
A dynamic theory of two-photon correlators measured in experiments with single molecular impurity centers has been developed.
The theory takes into account the interaction between optically active electrons of an impurity center and phonons, excitations
in tunneling systems of polymers and glasses, and transverse electromagnetic field. Both the correlator measured in the start-stop
regime and the “full” correlator have been analyzed, and equations for these correlators have been derived. An equation relating
these two correlators has been also obtained. The effect of the triplet level of an impurity molecule on the correlators leading
to bunching of spontaneously emitted photons has been studied. The two-photon correlators have been calculated numerically,
and their dependence on the incident light frequency and time between the pairs of detected photons in various realistic situations
has been derived.
Zh. éksp. Teor. Fiz. 113, 1606–1631 (May 1998) 相似文献
14.
G. M. Svishchev 《Optics and Spectroscopy》2004,97(2):204-209
A new method for measuring low-temperature absorption spectra of single impurity molecules using a laser confocal polarized-light transmission microscope is proposed. The sensitivity of this method is of the same order of magnitude as that of fluorescence excitation spectroscopy. Combined use of both methods makes it possible to study distributions of impurity molecules by the magnitude of fluorescence quantum yield and their correlations with the linewidth distributions, as well as to determine if spectral jumps lead to changes in the fluorescence quantum yield. 相似文献
15.
We present a new method for the measurement of the phase of ultrashort optical pulses with high spectral resolution. This
employs an interferometer with a monochromator in one arm. Two detectors operating in single photon and two-photon absorption
regimes monitor the output from the interferometer. Comparison of the signals from the two detectors gives a measurement of
the phase of the light pulse. The principles underpinning this technique are discussed and the experimental application to
picosecond pulses is demonstrated. 相似文献
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18.
<正>We theoretically and experimentally study the polarization and phase control of two-photon absorption in an isotropic molecular system.We theoretically show that the two-photon transition probability decreases when the laser polarization changes from linear through elliptical to circular,and the laser polarization does not affect the control efficiency of two-photon transition probability by shaping the spectral phase.These theoretical results are experimentally confirmed in coumarin 480.Furthermore,we propose that the combination of the laser polarization with the spectral phase modulation can further increase the control efficiency of the two-photon absorption. 相似文献
19.
G. T. Adamashvili 《Optics and Spectroscopy》2018,125(2):285-289
A theory of the optical surface two-photon small-amplitude breather in a multilayer system of the isotropic and anisotropic left-hand metamaterials, when there are a graphene monolayer (graphene-like twodimensional material) and a transition layer with impurity optical atoms (semiconductor quantum dots), is constructed. It is shown that the system of constitutive equations for two-photon transitions and wave equation for a surface plasmon–polariton TM mode are reduced to the nonlinear Schrödinger equation with damping. Explicit analytical expressions for a surface two-photon small-amplitude self-induced transparency breather (0π-pulse) are obtained. It is shown that the optical conductivity of graphene leads to the exponential damping of intensity of a surface two-photon nonlinear wave during the propagation. One- and two-photon small-amplitude breathers in graphene are compared, and it is shown that differences between their parameters are substantial. 相似文献
20.
The phosphorus-doped single wall carbon nanotube (PSWCNT) is studied by using First-Principle methods based on Density Function
Theory (DFT). The formation energy, total energy, band structure, geometry structure and density of states are calculated.
It is found that the formation energy of the P-doped single carbon nanotubes increases with diameters; the total energy of
carbon nanotubes with the same diameter decreases as the doping rate increases. The effects of impurity position on the impurity
level are discussed. It illustrates that the position of the impurity level may depend on the C-P-C bond angle. According
to the above results, it is feasible to substitute a carbon atom with a phosphorus atom in SWCNT. It is also found that P-doped
carbon nanotubes are N type semiconductor.
Supported by the Natural Science Foundation of Fujian Province of China (Grant No. A0220001) 相似文献