共查询到18条相似文献,搜索用时 156 毫秒
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HBr分子的爱因斯坦自发辐射系数的计算 总被引:1,自引:0,他引:1
本文从第一性原理出发,计算了HBr分子v≤7,J≤14,Δv=1,R,P支谱线的爱因斯坦自发辐射系数A^v‘J’v^nJ^n。测量了HBr红外发射的振转谱线强度,证实由理论计算获得的A^vJ’V^nJ^n系数是可靠的。 相似文献
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掺铒光纤(EDF)中的自发辐射噪声是影响掺铒光纤放大器(EDFA)工作性能和掺铒光纤激光器(EDFL)的起振特性的重要因素。自发辐射与泵浦方式紧密相关,研究脉冲泵浦下EDF的自发辐射具有重要的学术意义。从速率方程出发,建立了任意波形脉冲泵浦下EDF自发辐射的能级粒子数分布所满足的一元二阶变系数微分方程。由于没有封闭形式的解析解,采用杜哈梅尔方法,将泵浦脉冲波形进行分时段描述,每个小时段都有解析解,从而得到了自发辐射的平均功率表达式。分析结果表明,随着泵浦功率的增大,ASE的输出波形更接近泵浦光的波形,且泵浦光的毛刺对于ASE噪声的影响较小。 相似文献
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韦斯可夫-维格勒的自发辐射理论存在两个问题: 1.假定了每个时刻上能级布居数N2的衰减率与该时刻的N2值成正比,与它过去的值无关.这并非是理所当然的,而是马尔科夫近似下的结果.2.该理论中的比例常数取为爱因斯坦A系数,而A系数是在忽略了原子的有限大小条件下求出的结果. 相似文献
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本文对掺铒光纤的自发辐射特性进行了研究,分析了掺杂铒离子光纤的吸收截面、辐射截面、自发辐射谱、净增益系数等的特性,以及在掺铒光纤中,泵浦功率、自发辐射功率、光纤长度、自发辐射谱之间的关系,并用单色仪和波长为1.48um的InGaAsP半导体激光器测试了国产掺铒光纤的吸收谱和它的自发辐射谱。 相似文献
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当光子与服从玻尔兹曼分布的原子发生相互作用时,爱因斯坦对受激辐射、自发辐射和吸收的处理就能导出光子的普朗克分布律.同样,当光子与遵守费米-狄拉克或玻色-爱因斯坦分布的物质相互作用时也能得到普朗克定律. 相似文献
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Journal of Applied Spectroscopy - The radiation parameters, e.g., Einstein coefficients, oscillator strengths, Frank–Condon factors, and wavenumbers of vibronic transitions in the system of... 相似文献
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A molecular dynamics study of the microstructure and of diffusion in liquid MgO is reported. Models with 2,000 atoms were constructed in a wide temperature range, from 3,400 to 5,000 K, at ambient pressure. Analyses of the nearest-neighbor atomic exchange among coordination units, lifetime of the coordination units, temperature dependence of the velocity of the MgO x ?→?MgO x±1 transitions, and dependence of the mean-squared displacement on the number of transitions provide information on the structural dynamics and diffusion mechanism. A new method to calculate the diffusion coefficients is proposed, which yields coefficients in agreement with the Einstein equation, a result that sheds light on the mechanism of diffusion in liquid MgO. The dynamics is shown to be spatially heterogeneous and the origin of this heterogeneity is identified. 相似文献
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Einstein coefficients and oscillator strengths for electronic transitions in the Rydberg radical NaHe have been calculated with the molecular-adapted quantum defect orbital (MQDO) method. The correctness of our estimations has been established on the basis of their good agreement with the results of a reliable complex calculation available in the literature. Transition probability data involving Rydberg states lying higher in energy than those so far reported are supplied. 相似文献
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P. S. Kamenov 《Il Nuovo Cimento D》1991,13(11):1369-1377
Summary Proceeding from the drastic discrepancy between experimental data and theory, we show (contrary to other authors) that the
relations between the Einstein's coefficients are true for transitions from any of the excited levels and theground state of the quantum system only. The relations connecting those coefficients are derived for transitions betweenany two states; the corresponding cross-sections are calculated and it is shown (contrary to other authors) that the stimulated emission
cross-section may be large enough for the creation of gamma lasers. The new relation for Einstein's coefficients (and the
corresponding cross-sections) are fundamentally different from those known so far (74 years after Einstein). The results are
compared with experiment and the coincidence is very good. These investigations can lead to progress in the study of physical
processes in star atmospheres.
The author of this paper has agreed to not receive the proofs for correction. 相似文献
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D. Oba B.S. Agrawalla D.W. Setser 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,34(3):283-300
The RKR potential functions have been combined with the best experimentally based dipole functions to calculate the Einstein coefficients for HF/DF and HCl/DCl. Calculations were done for the Δν = 1,2,3 transitions for a wide range of ν′ (?15 for HF/DF and ?8 for HCl/ DCl) and J′ (?25). Experimental tests involving comparison of P- and R-branch line intensities for high-J′ transitions of the HF (ν1 → ν0, ν2 → ν1 and ν3 → ν2 bands) and the Δν = 2 and Δν = 1 transitions for HF/DF and HCl are done to examine the reliability of the Einstein coefficients for the rotational and vibrational levels, respectively. Good agreement is obtained for HF/DF even for the high-J′ R-branch intensities which vary markedly with J′. But the data suggest improvement is needed in the dipole functions for HCl (and DCl). 相似文献
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H. G. Demirkhanyan G. G. Demirkhanyan V. G. Babajanyan R. B. Kostanyan E. P. Kokanyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2008,43(1):13-18
Optical spectra of absorption and luminescence of LiNbO3:Yb3+ crystals are investigated experimentally and theoretically. Within the framework of the point charge approximation of crystal field, the Stark problem is solved: crystal field parameters and wave functions of Stark states are determined. Line strengths due to indirect electric-dipole and magnetic-dipole inter-Stark transitions are calculated and values of the Judd-Ofelt parameters are determined. Values of the branching ratios of luminescence. Einstein coefficients and, lifetime of the excited sublevel are calculated. A satisfactory agreement of calculated results with experimental data is obtained. 相似文献
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Adriana Predoi-Cross Kyle Hambrook Chad Povey Daniel Hurtmans Georg Ch. Mellau 《Journal of Molecular Spectroscopy》2008,248(2):85-110
This paper reports accurate line positions, intensities, self-broadening, -shift and -line mixing coefficients for 56 rotational transitions from multispectrum fits of low noise, high-resolution Fourier-transform spectra. The measured line intensities are within the statistical spread of the previous measurements available in the literature—thus contributing to the efforts to measure the oxygen A-band intensities with an accuracy better than 1%. We determined the integrated band strength and Einstein A coefficient. Using our spectrum calibration method we could clearly show for the first time that there is a meaningful statistical discrepancy in the frequency standards used in spectroscopic studies for the oxygen A-band. We were able to explain how this discrepancy leads to two different sets of shifts reported in the literature and demonstrate the need for precise frequency-type transition wavenumber measurements of the oxygen A-band transitions. We observed deviations from the conventional Voigt profile due to speed-dependent broadening and line mixing effects. Dicke narrowing was observed on a selected group of spectra recorded at pressures between 98 and 337 Torr. The Dicke narrowed lineshapes were best modeled using a Galatry profile implemented using a fixed value for the velocity-changing collision rate. The weak line mixing coefficients were determined from fits using the speed-dependent models. Exponential Power Gap (EPG) and Energy Corrected Sudden (ECS) scaling laws were used to calculate the self-broadening and self-line mixing coefficients. 相似文献
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When the gas particles, which can be considered as a two level quantum system, are affected by frequent collisions with buffer gas particles (thermal reservoir), the spectral densities of the Einstein coefficients for absorption and induced emission are unequal to each other far from the absorption (emission) line. The relationship between the spectral densities at the specified condition reveals new physical phenomena. The mostly convincing example is the fact that population inversion is established in a two level system under nonresonance optical excitation. This effect is experimentally observed as a lasing on sodium resonance transitions. 相似文献