Experimental investigation of the line center of Hg intercombination spectral line 253.7 nm perturbed by Kr

The collision broadening and shift of the Hg intercombination spectral line 253.7 nm (6¹S₀–6³P₁) perturbed by Kr has been investigated using a high-resolution scanning Fabry–Perot interferometer. The values of the pressure broadening and shift coefficients β and δ, respectively, for the studied line have been obtained. The obtained coefficients β and δ are compared with their corresponding published experimental values and also those calculated using Lindholm–Foley impact theory.     

Li(2p $leftarrow$ 2s) + Na(3s) pressure broadening in the far-wing and line-core profiles

This work reports pressure-broadening line-wing and line-core of the lithium Li (2p $leftarrow$ 2s) resonance line perturbed by ground sodium Na (3s) atoms. In far-wing regions, the calculations are performed quantum-mechanically and are intended to examine the photoabsorption coefficients at diverse temperatures. The results show the existence of three satellites, in the blue wing near the wavelengths 470 nm and in the red wing around 862 nm and 1070 nm. For the line-core region, by adopting the simplified Baranger model, the line-width and line-shift rates are determined, and their variation law with temperature is examined. No published data were found to compare these results with.     

Calculated line broadening coefficients in the ν2 band of CH3D perturbed by helium

Line broadening coefficients have been calculated, at room temperature, for lines in the P and R branches of the ν₂ band of monodeuterated methane. A properly symmetrized semiclassical model with parabolic relative trajectories has been used. Two interaction potential models have been considered. The first is a Lennard-Jones type atom-atom potential, while the second one was derived from ab initio calculations. The calculated line widths were compared to the available experimental data and a satisfactory agreement was found, although the model contains no other adjustable parameters than the four atomic Lennard-Jones ones. Nonetheless, failures of calculations have also been evidenced for the highest rotational quantum numbers.     

Measurements of O2-broadening and -shifting parameters of water vapor spectral lines in the second hexad region

Oxygen pressure induced broadening and shifting coefficients for water vapor absorption lines in the 8600–9010 cm⁻¹ region have been measured and calculated. The spectra were recorded with a Bruker IFS 125HR spectrometer at a spectral resolution of 0.01 cm⁻¹ for lines with angular moment of the upper states up to 10. Calculations of line broadening and shifting coefficients are performed using a semi-empirical approach. The method is based on the impact theory of broadening, and includes the correction factors whose parameters can be determined by fitting the broadening or shifting coefficients to the experimental data. The comparison of our calculations with the experimental values argues that the semi-empirical method is quite acceptable for the determination of the water vapor absorption line profile parameters.     

Production of the excited Ne(2p 5 3p) atoms by dissociative recombination in the afterglow of high frequency neon discharge

Experimental results are presented of the measurements of the population of the Ne(2p ⁵ 3p) atoms from the time dependences of the relative intensities of the spectral lines corresponding to 3s -3p transitions in the afterglow period of a high frequency neon glow discharge at pressures from 266 Pa to 4 kPa. The partial recombination coefficients were determined from these measurements as a function of gas pressure and they are compared with measurements of other authors. It is shown that at low gas pressures the Ne(2p ⁵ 3p) atoms are also populated only in the dissociative recombination in spite of the fact that the dominant loss process of charged particles is the ambipolar diffusion.     

Experimental line broadening and line shift coefficients of the acetylene ν1 + ν3 band pressurized by hydrogen and deuterium and comparison with calculations

Theoretical and experimental values have been determined for the pressure broadening of the ν₁ + ν₃ band of acetylene by hydrogen and deuterium at 195 K, and experimental values of the pressure shifts have been determined. Theoretical values have been calculated on the basis of a recent potential energy surface using the close coupling scheme. We discuss the detailed contribution of the various rotational angular momenta of the perturbing gas and the ortho and para contribution to the total pressure broadening cross-sections. We give routes to circumvent the computational cost of such calculations. Experimental values have been measured using a tunable diode laser spectrometer assuming a Voigt line shape. These pressure broadening parameters are compared with measurements performed recently at room temperature and with present measurements performed at 195 K in the ν₁ + ν₃ band of acetylene. A satisfactory agreement is obtained with the present results and available ones at 295 K.     

Shift Coefficients and Self-Pressure Broadening of H2 16O Lines in the Range 1950–2750 cm−1

Experimental values of the shift coefficient and self-pressure broadening by the own pressure have been determined for some spectral lines of water vapor in the range 1950–2750 cm^–1. A comparison with the calculated data obtained on the basis of the Robert–Bonamy method has been performed. A satisfactory agreement between the theory and experiment has been obtained.     

Measurements and calculations of H2-broadening and shifting parameters of water vapour transitions in a wide spectral region

ABSTRACT

The water vapour line broadening (γ) and shifting (δ) coefficients for 149 lines of 10 vibrational bands 2ν₁, 2ν₃, ν₁?+?ν₃, 2ν₂?+?ν₃, ν₁?+?2ν₂, ν₂?+?2ν₃, 2ν₁?+?ν₂, 3ν₂?+?ν₃, ν₁?+?3ν₂ and 6ν₂ induced by hydrogen pressure were measured with a Bruker IFS 125 HR spectrometer. The measurements were performed at room temperature with a spectral resolution of 0.01 cm^–1 and in a wide pressure range of H₂. The calculations of the broadening coefficients γ and δ were performed in the framework of the semi-classical method using an effective vibrationally dependent interaction potential. The optimal sets of potential parameters that give the best agreement with the measured broadening coefficients for each vibrational band separately were found. Then combined experimental data of 16 vibrational bands of H₂O perturbed by H₂ were used to determine the analytical dependence of some potential parameters on vibrational quantum numbers. The analytical expressions that reproduce the broadening coefficients γ for different vibrational bands are proposed.     

Work function dependence of the Li(2p) formation in slow collisions of Li atoms with partially cesiated tungsten surfaces

The reflection of Li atoms from partially cesiated polycrystalline tungsten is studied at impact energies between 100 and 1000 eV at near-grazing incidence angles. The work function dependence of the yield for Li(2p) formation is studied between φ = 1.27 and 4.8 eV together with the probability for Li⁺ formation. While Li⁺ formation is only important for φ > 3.5 eV, the probability for Li(2p) excitation has its maximum of several percents near (at φ = 1.7±0.1 eV), but not exactly at the minimum of the work function. The dependence of the absolute photon yield is given as a function of the impact energy. The polarization properties of the Li(2p → 2s) photons are also studied. The angular distribution of the excited Li(2p) atoms for various φ values is obtained by applying photon-scattered atom coincidence techniques. An effort is made to understand the Li(2p) formation on cesiated metal surfaces on the basis of the nonadiabatic coupling between different Li states induced by the motion of the Li atom relative to the surface.     

Measurements of self-broadening and self-pressure-induced shift parameters of the methane spectral lines in the 5556-6166 cm range

The absorption spectra of methane at different path lengths and different pressures for three temperatures 180, 240 and 296 K have been recorded in the 5556-6166 cm⁻¹ region using the Bruker IFS 120 HR and 125 HR high-resolution Fourier transform spectrometers. The multispectrum fitting procedure has been applied to these spectra to recover the spectral line parameters. The main goal of this procedure was the determination of self-broadening and self-pressure-induced shift coefficients and the exponents of their temperature dependences. These parameters have been derived for 406 assigned lines with good values of the signal to noise ratio. The rotational dependence of these parameters is discussed.     

Elastic scattering of electrons by hydrogen atoms in the (2p) state

Conclusion Since our results are the first set of results in this field, their accuracy can be judged when further results through other methods and through experiment are available.The author is grateful to Dr. J. N. Das for his constant help and encouragement in the preparation of this paper. The numerical results reported in this paper have been calculated on the IBM 1130 at Calcutta University.     

Determination of perturbations in the semi-degenerate 4f 4d 4p → 2p Li(I) line emitted by an electrolytic plasma

By considering a superimposed, uniform electric field E polarized along the observation direction and neglecting ionic perturbation, we obtain theoretical profiles showing a forbidden peak higher than the allowed one, just as in experimental profiles. We find best agreement for $\text{|}\text{E}\text{| = 160 kV cm}{}^{\mathrm{?1}}$, N_e = 3 × 10¹⁷cm^?3. These results imply Li, K, and Cl concentrations (atoms+ions) close to those of the electrolytic bath and a temperature below 6700 K. Ionic perturbations must be studied by leaving off the quasi-static ionic field concept.     

Interatomic potentials for the ground state X 0 and the two excited states 1, 0 of the intercombination cadmium line 326.1 nm broadened by Kr pressure

The temperature dependence of the Cd line absorption profile at 326.1 nm perturbed by Kr has been carefully studied over a spectral range extending from 800 cm⁻¹ in the blue wing to 1200 cm⁻¹ in the red wing using a high-resolution double-beam spectrometer. The atomic densities of krypton (N_Kr) and cadmium (N_Cd) were (2.015±0.07)×10¹⁹ and (3.62±0.05)×10¹⁸ cm⁻³, respectively. The temperature dependence of the studied line profile was analyzed in the framework of the quasi-static theory. The van der Waals coefficient differences between the ground ¹0⁺ state and the two excited states ³0⁺ and ³1 (ΔC₆⁰ and ΔC₆¹) were obtained from the near red wing profile using Kuhn's law. The values of ΔC₆⁰ and ΔC₆¹ are found to be equal to 37.8±2 and 58.5±3 eV Å⁶, respectively. The ground (X ¹0⁺), and the excited (³1, ³0⁺) state potentials at the internuclear separations from 3.2 to 6.3 Å were determined. The well depths with their positions for these states are respectively equal to 134±7 cm⁻¹, 3.95±0.2 Å; 72.3±4 cm⁻¹, 4.95±0.3 Å; and 471±12 cm⁻¹, 3.6 Å. The obtained well depths with their allowable errors are in good agreement with the values obtained before for the Cd-Kr system from some theoretical results and molecular beams experiments.     

Line profile study from diode laser spectroscopy in the CH4 2ν3 band perturbed by N2, O2, Ar, and He

We present a line profile study for two lines in the 2ν₃ band of CH₄ recorded with a frequency stabilized tunable diode laser spectrometer. The broadening and narrowing (Dicke effect) parameters of the R(0) line perturbed by N₂, O₂, and He are derived from a simultaneous fitting of spectra at pressures from 20 to 300 Torr by using the soft and hard collision models. These parameters are determined for the A and F components of the unresolved R(3) manifold perturbed by N₂, Ar, and He from the line profile analysis of spectra at pressures between 50 and 500 Torr. The line mixing effect between the two F components is also taken into account and the absorber speed dependent effect on broadening is estimated for N₂ and Ar.     

类Ne等电子系列离子(Z=11,…,18)2p~53s—2p~6辐射跃迁的多组态相对论理论计算

利用多组态DiracFock(MCDF)理论方法,系统研究了延迟、相关和相对论效应对类Ne等电子系列离子(Z=11,…,18)的较低的激发组态2p53s和基组态2p6的能级结构及其能级之间辐射跃迁特性的影响.给出了2p53s1,3P01—2p61S0电偶极(E1)共振和复合跃迁、2p53s3P02—2p61S0磁四极(M2)跃迁和2p53s3P00—2p53s3P01磁偶极(M1)跃迁的跃迁能以及激发态1P01,3P00,3P01,3P02的辐射寿命,所得结果与最新实验观测和其他理论计算进行了比较 关键词： MCDF方法 延迟和相关效应 跃迁概率     

Semiclassical line broadening calculations,using an ab initio potential energy surface,in Q‐branch and S‐branch of N2 perturbed by H2

In order to improve the accuracy of Raman combustion diagnostics, the broadening coefficients of N₂ perturbed by H₂ for Q‐branch and S‐branch have been calculated by the semiclassical Robert–Bonamy model using an ab initio potential energy surface. The calculations have been performed for a large range of temperatures (from 77 to 800 K) and J rotational quantum numbers (from 0 to 60). This paper shows that our results and their temperature dependence are in good agreement with earlier published experimental and theoretical data. Moreover, our results improve the semiclassical calculations made earlier with an adapted analytical potential. The results, obtained at high temperatures and for a large range of rotational quantum numbers, are presented in order to be implemented for optical diagnostics in combustion media. Copyright © 2012 John Wiley & Sons, Ltd.     

Effect of Nd3+ Concentration on the Laser Performance of a New Laser Crystal∶Nd∶NaY(WO4)2

The transmission and emission spectra of a new crystal, Nd∶NaY(WO4)2 (Nd∶NYW) have been measured. Using a Ti∶Sapphire laser as the pump source, the laser performances of Nd:NYW crystals with different concentrations are compared for the first time. The Nd3+ concentrations used are 1, 2, 4 and 5 at.-%. The experiments show that 2 at.-% is the optimum concentration. When the incident pump power is 575 mW, the 1.06 μm output can reach 184 mW, corresponding to an optical to optical efficiency of 32%. The experimental results show that the work is significant to the further research and praction application of this promising laser crystal.     

Broadening of the R(0) and P(2) lines in the CO fundamental by helium atoms from 300 K down to 12 K: Measurements and comparison with close-coupling calculations

We present measurements of He-broadening parameters for the R(0) and P(2) lines in the fundamental band of ¹³CO at different temperatures between 12 K and room temperature. The broadening parameters are determined, taking into account confinement narrowing, by simultaneous least-squares fitting of spectra recorded using a frequency stabilized diode laser spectrometer. The pressure broadening cross sections are deduced and compared to close-coupling calculations and earlier results obtained for rotational transitions of ¹²CO.     

Diode-laser spectroscopy: Temperature dependence of R (0) line in the ν4 band of CH4 perturbed by N2 and O2

In this paper, we present a line profile study of the R (0) line in the ν₄ band of methane diluted in nitrogen and oxygen, from room temperature to 153 K. The measurements were performed over a total pressure range from 14 to 128 mbar. The collisional broadening and narrowing (Dicke effect) coefficients are derived from a fit of the experimental spectra by using the soft and hard collision models, taking into account the Dicke effect. For higher pressures, we have fitted the data with a model taking into account simultaneously the Dicke narrowing and the speed dependence effect. Finally, we have deduced the parameter n of the temperature dependence (inverse power law) of the broadening coefficients for the CH₄-N₂ and CH₄-O₂ gas mixtures.