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131.
We study theoretically the spectral intensity evolutions of the femtosecond Gaussian and parabolic pulses with different initial pulse energies and compare the nonlinear compressions of these pulses based on a meter-long hollow-core fiber filled with neon for different initial pulse durations. The pulses are first coupled into gas-filled hollow-core fiber for spectrum broadening, then compressed by the optimal chirp compensation. The parabolic pulse possesses a shorter pulse duration, larger peak power, and cleaner wings than Gaussian pulse. The properties are useful for compressing the pulses and thus generating the high-energy, short-duration pulses. 相似文献
132.
Jamel Salem Jacques Walrand Ghislain Blanquet 《Journal of Molecular Spectroscopy》2005,232(2):247-254
Pressure broadening of phosphine lines by helium and argon at room temperature has been experimentally investigated by high-resolution diode-laser spectroscopy. The broadening coefficients are measured for 38 transitions of PH3 in the QR branch of the ν2 band and in the PP and RP branches of the ν4 band. The recorded lines with J values ranging from 3 to 14 and K from 0 to 10 are located between 1062 and 1094 cm−1. The retrieval of the collisional widths is carried out by fitting each spectral line with a Voigt profile, a Rautian profile and a speed-dependent Rautian profile. The latter model provides larger broadening coefficients than the Voigt model. They are also calculated on the basis of a semiclassical model involving the atom-atom Lennard-Jones potential. The theoretical results are in reasonable agreement with the experimental data and reproduce the J and K dependencies of the broadenings. 相似文献
133.
By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d^3 electronic configuration,the values of all the parameters in the expressions of thermal shift (TS) and thermal broadening (TB) due to EPI for the ground level,R level and R line of MgO:Cr^3 have microscopically been evaluated;and then,TS and TB of R line and various contributions to them have uniformly been calculated.The results are in very good agreement with the experimental data.It is found that all the three terms of TS due to EPI are red shifts;the Raman term is the largest one,and the optical-branch term and neighbor-level term are important for TS;the contribution to TS from thermal expansion is blue shift,which is also important.The R-line TS of MgO:Cr^3 comes from the first-order term of EPI.The elastic Raman scattering of acoustic phonons plays a dominant role in R-line TB of MgO:Cr^3 .For both TS and TB,it is very important to take into account all the admixtures of basic wavefunctions within d^3 electronic configuration. 相似文献
134.
135.
J.P. Bouanich A. Predoi-Cross R.L. Sams C.P. Rinsland V. Malathy Devi 《Journal of Molecular Spectroscopy》2005,231(1):85-95
A semiclassical theory based upon the Robert-Bonamy formalism has been developed to explain the experimental measurements of self-broadening, self-induced pressure shift coefficients in the ν1,ν2, 2ν2 bands of H12C14N and the 2ν1 band of H13C14N, as well as the temperature dependences of these parameters with special emphasis on the ν2 band. Our calculations include only electrostatic interactions and neglect the vibrational dependence of the isotropic part of the intermolecular potential, which probably has a weak contribution to the HCN self-shifts for the bands investigated in this study. The agreement between theory and measurements is good in the cases of self-broadening coefficients and their variation with temperature, as well as the self-shift coefficients determined at room temperature. However, the observed temperature dependence of self-shift coefficients in the ν2 band is different from that derived theoretically. 相似文献
136.
G.Yu. Golubiatnikov M.A. Koshelev A.F. Krupnov 《Journal of Molecular Spectroscopy》2003,222(2):191-197
Low pressure measurements of broadening parameters of the 118.75 GHz fine structure line of oxygen molecule have been made by a BWO-based spectrometer with acoustic detector (RAD) at room temperature. Pressure broadening parameters were obtained for the buffer gases O2, N2, Ne, He, Ar, H2O, CO2, and CO and have the following values 2.23 ± 0.01, 2.245 ± 0.02, 1.375 ± 0.02, 1.62 ± 0.03, 2.005 ± 0.02, 2.52 ± 0.04, 2.66 ± 0.08, and 2.31 ± 0.05 MHz/Torr, respectively. Measured central frequency is 118 750.340 ± 0.007 MHz. The central frequencies and broadenings by O2 and N2 of fine structure lines 1+, 5−, 7+, 11+, and 15− belonging to the 60-GHz band are also measured. Comparison of previous and recent data on electronic, rotational, and fine structure lines broadenings reveals their close values (within 10%) and dependencies on corresponding rotational quantum numbers for these different oxygen spectra stretching from millimeter through submillimeter up to the optical bands. Such similarity could be used for estimation of the broadenings of not measured yet oxygen lines. 相似文献
137.
Using a semiclassical approach, we have considered electron-, proton-, and ionized helium-impact line width and shifts for
32 Y III multiplets.
Published in Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 4, pp. 476–481, July–August, 1998. 相似文献
138.
活化LaNi5衍射峰各向异性应力展宽模型在LHPM程序中的实现 总被引:1,自引:1,他引:0
在活化LaNi5的粉末衍射轮廓中会出现较明显的各向异性展宽现象,这给衍射数据的Rietveld分析带来相当的难度.Rodriguez-Carvajal提出了一个唯像模型,只需精修少量的参数就能对于各向异性展宽的衍射峰获得较好的拟合.基于这个模型的原理,本文描述了活化laNi5衍射峰各向异性应力展宽模型在LHPM 6.5中的实现过程,并将所得结果与FullProf 2000的结果进行了比较. 相似文献
139.
GAO Zhi HU Limin & SHEN Yiqing Institute of Mechanics Chinese Academy of Sciences Beijing China 《中国科学G辑(英文版)》2004,47(3):338-351
The gas pressure in a laser cavity of flowing chemical oxygen-iodine laser (COIL)is about 133.31333 Pa[1]. In this pressure range, effects of homogeneous and inhomo-geneous broadening competing with each other on the performances of a COIL are no-ticeable. Generally, a rate equation (RE) model is adopted to the performance modeling of a supersonic COIL, such as in refs. [1—4]. This model assumes the spectral line pro-file is homogeneously broadened. Homogeneous broadening assumption sim… 相似文献
140.
本文讨论了调制信噪比是如何影响正弦位相调制(SPM)干涉仪精度的。为了改善调制信噪比,本文提出一种新的SPM干涉仪,其中参考波和检测波由一加了正弦电压的LiNbO_3电光晶体所调制,这种方法的调制信噪比较振镜调制法高,因此能用电光调制器提高SPM干涉仪的测量精度。 相似文献