Temperature dependence of rare gas broadening and shifting of first harmonic lines of H35Cl

Widths and shifts of HCl vibration-rotation lines, pressurized by rare gases, have been measured for the 0–2 band as functions of temperature. The results reported here complement previously published results on the fundamental band. The model of Smith, Giraud and Cooper is used to calculate widths and shifts; good agreement is obtained between experiment and theory. Problems concerning the accuracy of available potential energy surfaces and the calculation of differential cross sections are discussed briefly.     

A comparison of foreign gas broadening and shift of neon and argon emission lines

Foreign gas broadening and shift coefficients for Ne and Ar emission lines produced in a high pressure (0·5-2·0 atm) He discharge have been measured. The shift coefficients vary significantly for different transitions. This variation results from the differing excited state potentials for the He-Ne¹ and He-Ar¹ collision pairs, which must be included in any reasonable quantum-mechanical calculation of line shifts. Even the small differences in broadening coefficients demonstrate the inadequacy of calculation of broadening from equations based on the Lindholm⁽¹⁾-Foley⁽²⁾ theory of collision broadening.     

A translational heat-bath model for foreign gas broadening of spectral lines—I. Variational methods

A new formalism of Green's functions is used for discussing foreign gas broadening of atomic spectral lines. In the present work, the translational degrees of freedom are separated from the internal degrees of freedom by a translational heat-bath model. The conditions of a heat bath, weak and binary collisions lead to a Lorentzian line shape in the center of the line and to a rapid decay of the line wings. For weak interaction potentials, a new explicit expression for line broadening, which demonstrates this behaviour, is obtained.     

A translational heat-bath model for foreign gas broadening of spectral lines—II. The T approximation

The theory of foreign-gas broadening is developed for a central potential by using the T approximation, in a Green's functions formalism. The translational degrees of freedom of the absorbing and foreign gases are separated from the internal degrees of freedom by a translational heat bath model. The line profile is expressed by a Lorentzian in which the half width and shift are functions of frequency. A general method is developed for calculating the half width as a function of frequency. The Lorentzian line profile obtained for a hard-core potential is compared with the explicit line profile obtained for weak potentials by the Born approximation. The results of the present paper are compared with those of other theoretical studies.     

Dicke narrowing and pressure broadening in the infrared fundamental band of HCl perturbed by Ar

Dicke narrowing due to state preserving but velocity changing collision has been observed in several high-J vibration-rotation transitions of the fundamental band of HCl with Ar as the collision partner. Because of the long wavelength of radiation and the small diffusion coefficient, the narrowing occurs at a relatively low pressure of ∼200 Torr. A difference frequency laser system was employed for the studies of linewidths and lineshapes over the temperature range of 297–420 K. The results were analyzed using the diffusion model.     

HCl vibrational fundamental band: Line intensities and temperature dependence of self-broadening coefficients

Self-broadening in the vibrational fundamental of HCl is inversely proportional to the temperature for transitions which lie near the Boltzmann rotational maximum and becomes monotonically less temperature-dependent as the rotational quantum number increases. We have determined the rotationless transition moment to have the value of 5.57 ± 0.13 × 10^?3 (Debye)² and the first Herman-Wallis factor, C = ?2.543 ± 0.019 × 10^?2.     

Temperature dependence of the fundamental energy gap in GaAs

We show that the temperature dependence of the fundamental gap energy E₀ of GaAs can be theoretically described within the empirical local pseudopotential approach for the band structure. For the calculation we take into account the thermal expansion effect and two contributions of the deformation potential type electron-phonon interaction. These are the Debye-Waller part, which shifts the gap to lower energies with increasing temperature, and the self-energy part, which partly cancels the shift caused by the Debye-Waller part.     

Temperature dependence of the linewidths of shallow impurity spectral lines

A pronounced broadening of shallow donor transition linewidths in GaAs and CdTe by a factor of 2-2·5 on raising the sample temperature from 4 K to 10 K is reported. At low temperatures such impurity lines are inhomogeneously broadened by the Stark effect due to random electric fields arising from the ionized impurities in the crystal. The experimental observation is analysed and explained in terms of the temperature dependent spatial correlation between ionized donors and acceptors in the crystal.     

Noble-gas broadening of vibration-rotation lines belonging to diatomic molecules—II. Theoretical calculations of HCl lineshifts and widths

The Anderson-Tsao-Curnutte theory is generalized to account for the vibrational dependence of line shifts and widths in the case of noble-gas-broadened HCl lines. Buckingham's intermolecular potential is used and good agreement with experimental values is obtained. Comparison is made with Herman and Tipping's semi-empirical potential. The conditions under which the theory should be applied are pointed out, especially cutoff procedures, trajectory shapes, and velocity averaging.     

Stark broadening of neutral helium lines

Using a semiclassical approach for the Stark broadening of atomic lines, we have calculated electron and proton impact line widths and shifts of 56 neutral He lines in the ultraviolet, visible and i.r. region of the spectrum. The comprehensive set of results obtained is used for investigation of Stark-broadening parameter regularities within the spectral series.     

Noble-gas broadening of vibration-rotation lines belonging to diatomic molecules—I. Experimental results for HCl lineshifts and widths

Pressure effects in the vibration-rotation spectra of gaseous hydrogen chloride broadened by argon and xenon have been investigated under high perturber pressures with the use of high-resolving power spectrometers, particularly a SISAM. The experimental determination of the instrument function is discussed in detail. Observed shifts and widths are compared with previous results, and their variation with vibrational transitions is determined.     

Temperature dependence of the fundamental absorption edge of ferroelectric crystals of dimethylamine chlorocuprate

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 56, No. 1, pp. 86–89, January, 1992.     

气体的摩尔热容量随温度变化的实验研究

采用压力传感器和温度传感器,通过数据接口由计算机实时采集数据并进行处理,观察到气体的热力学过程的状态变化,测得了氧气的摩尔热容量CV随着温度的变化.结果表明氧气的CV随温度的变化有一突变,这与能量均分定理所描述的基本一致,氧气的振动自由度被冻结的温度在240K左右.     

Stark broadening of neutral sodium lines

A semiclassical approach has been used to evaluate Stark broadening of atomic lines and also electron-and proton-impact line widths and shifts of 30 neutral sodium lines. The results are used to investigate Stark broadening-parameter regularities within the spectral series.     

Stark broadening of neutral potassium lines

Using a semiclassical approach, we have calculated electron-proton and Ar II impact line widths and shifts of 50 neutral potassium lines. The comprehensive set of results obtained is used for investigation of Stark-broadening-parameter regularities within the spectral series.     

A translational heat bath model for foreign gas broadening of spectral lines—III. W.K.B. approximation for satellite bands

The W.K.B. approximation for the line-wing profile is developed by using a translational heat bath model. A general expression is developed for the semiclassical shape of satellite bands. The results are compared with other works.     

Collisional broadening of infra-red absorption lines

The Lorentz half-widths of collision-broadened lines in the rotation-vibration bands of diatomic molecules vary with line number |m| in the P and R branches. The observed variation of half-width for lines in the 0 → 1 and 0 → 2 bands of CO and HCl are interpreted in terms of a simple fitting procedure. One dominant source of line broadening is assumed to consist of diabatic hard collisions involving transitions from each rotational level to all higher rotational levels; the effectiveness of this process, which varies from line to line, is described in terms of an empirically adjusted collision cross section, a maximum collision parameter related to independently measured molecular properties, and upon the availability of the required energy and angular momentum in molecular collisions. The second source of line broadening, assumed to be the same for all lines, includes all other types of collisions and is represented by a single empirically adjusted cross section. The simple fitting procedure is applied successfully to self-broadening of CO lines and to foreign-gas broadening of CO and HCl; for HCl self-broadening an additional cross section for resonant-dipole processes must be included. Possible applications of the fitting procedure to HBr, HF, and CO₂ are discussed. The simple procedure presented represents an approximation that may prove useful pending the development of readily applicable complete theories based on first principles.     

Temperature dependence of the fundamental absorption edge in CuGaSe2

The temperature dependence of the fundamental absorption edge in CuGaSe₂ single crystals was determined in the temperature range from 15 to 300 K. Above about 120 K the gap energy changes linearly with temperature with dE_g/dT = ? (2.1 ± 0.1) eV K^?1. The downshift in dE_g/dT of the I–III–VI₂ compounds compared to their II–VI analogs is discussed accounting for the p-d hybridization of the uppermost valence band.