Using an interferometric method, detailed analysis of the line shapes of the self-broadened 748.8 nm Ne line emitted from the glow discharge at low pressure of neon was performed in wide temperature range. Systematic departures from the ordinary Voigt profile were observed. We have shown that the dissociative recombination of molecular Ne^{+}_2 ions which gives rise to the non-thermalized neon atoms may be regarded as the main process responsible for the distortion of the profile of the investigated line.
Assuming that V(x) ≈ (1 - μ) G_1(x) + μ L_1(x) is a very good approximation of the Voigt function, in this work we analytically find μ from mathematical properties of V(x). G_1(x) and L_1(x) represent a Gaussian and a Lorentzian function, respectively, with the same height and HWHM as V(x), the Voigt function, x being the distance from the function center. In this paper we extend the analysis that we have done in a previous paper, where μ is only a function of a; a being the ratio of the Lorentz width to the Gaussian width. Using one of the differential equation that V(x) satisfies, in the present paper we obtain μ as a function, not only of a, but also of x. Kielkopf first proposed μ (a, x) based on numerical arguments. We find that the Voigt function calculated with the expression μ (a, x) we have obtained in this paper, deviates from the exact value less than μ(a) does, specially for high |x| values.
Assuming that V(x) ≈ (1 - μ) G_1(x) + μ L_1(x) is a very good approximation of the Voigt function, in this work we analytically find μ from mathematical properties of V(x). G_1(x) and L_1(x) represent a Gaussian and a Lorentzian function, respectively, with the same height and HWHM as V(x), the Voigt function, x being the distance from the function center. μ is obtained as a function of a, a being the ratio of the Lorentz width to the Gaussian width. We find that, the Voigt function calculated with the expression we have obtained for μ, deviates from the exact value less than 0.5% with respect to the peak value.
High-resolution photoacoustic spectra of trinitrato-bis[N-(2-pyridyl-methylene)-N'-benzoyl-hydrazine]R (III), (R = La, Ce, Pr), and binitrato-bis[N-(2-pyridylmethylene)-N'-benzoyl-hydrazine]R(III) nitrate (R=Y, Nd, Eu, Yb, Tb, Gd, Ho, Dy, Er) complexes, in the visual region, were studied for powder samples. Very intense photoacoustic spectra of various shapes were attributed to the intraligand transitions of the π → π* type located mainly on the C=N group and the n → π* transitions located on the carbonyl group. The intensity of these transitions essentially depends on the type of rare earth ions. The existence of f-f electron transitions could influence the relaxation processes, which play an important role in intensity determination of the above transitions. For many investigated samples the energy levels of excited states of rare earth ions were identified (f-f electron transitions). The radiation energy for some of the rare earth ions were compared with the d-d electron transitions of certain copper(II) organometallic complexes, which are very important in biogenic systems. The correlation between ions with localized and extended wave functions is suggested.
The 301.5 nm electric-field-induced quench radiation on a thermal beam of neutral Bi atoms in the metastable 6p^{3} ^{2}P_{3/2} state for transition to the ground 6p^{3} ^{4}S_{3/2} state was observed. The measurement of the Stark-enhanced intensity of the radiation as a function of the electric field yields a relationship between the field-free-decay rates for transitions between the metastable 6p^{3} ^{2}P_{3/2} state and the nearby states that are mixed in by the field. Using the known decay rates, the measurement sets an approximate transition rate of A(6p^{3} ^{2}P_{3/2} → 6p^{2}7s ^{4}P_{1/2}) ≈ (0.50 ± 0.05) s^{-1}.
The extended Omont-Kaulakys-Ueda treatment of collisional effects on quasi-Rydberg states, in which the perturbation of the lower state is taken into account, is applied to mercury-argon system. The pressure shift coefficients of 6p-ns and 6p-nd spectral lines are calculated and compared with available experimental data.
The collision-time asymmetry coefficients as well as the pressure broadening and shifting rates of the ^{114}Cd 326.1 nm line perturbed by noble gases are calculated in the framework of the non-adiabatic semi-classical method using the Czuchaj et al. potentials. The theoretical values are compared with experimental results determined recently by means of laser-induced fluorescence technique.
Shapes of self-broadened argon lines 687.1 nm (4d_{5}-2p_{10}), 703.0 nm (3s_{5}-2p_{9}), 750.3 nm (2p_{1}-1s_{2}) as well as the neon line 748.8 nm (3d_{3}-2p_{10}) emitted from glow discharges at low pressures were analysed using a Fabry Perot interferometer. We showed that the dissociative recombination of Ar^{+}_{2} (or Ne^{+}_{2}) molecular ions which gives rise to the density of non-thermalized atoms, may be regarded as the main process responsible for the distortion of the profiles of the above lines. The distorted profiles were analysed as superposition of the Ballik profile for thermalized atoms and the modified Ballik profile for non-thermalized atoms. The Lorentzian and Gaussian widths as well as relative densities of non-thermalized and thermalized atoms were determined.
We report on very precise measurements of the absorption profile of the 326.1 nm resonance line of cadmium broadened by interactions with the ground state Cd atoms under thermal equilibrium. The experimental red wing profiles, corrected for the Boltzmann factor at different temperatures, are analysed in terms of the long-range potential parameters including dispersion and resonant interactions. The resonant interaction energy constant C_3 is calculated to be 2.31×10^{-2} eV Å^3 and the van der Waals constant C_6 for difference potentials between the ground state X^10^+_ g and the excited states B^30^+_u and A^31_u of Cd_2 derived experimentally are found to be (182.6± 8) eV Å^6 and (289±4) eV Å^6, respectively. The former is determined for the first time and the latter is considerably corrected in comparison to earlier determination. The van der Waals constant C_6 for the ground state of Cd_2 is discussed and estimated to be C_6^g=(247± 40) eV Å^6.
Using a laser-induced fluorescence method, detailed analysis of profiles of the ^{114}Cd 326.1 nm line perturbed by krypton was performed which revealed departures from the ordinary Voigt profile. These departures are shown to be consistent with fits of experimental profiles to a speed-dependent asymmetric Voigt profile. Coefficients of the pressure broadening, shift, and collision-time asymmetry are determined and compared with those calculated in the adiabatic approximation for the van der Waals, Czuchaj-Stoll, and Morse potentials.
Half widths of 24 ArI lines from a wide interval of the spectrum and from a large range of excitation energies were measured. A wall-stabilized arc at atmospheric pressure was applied as a plasma generator. Electron densities of the plasma of the order of 10^{16}-10^{17} cm^{-3} were obtained on the basis of hydrogen H_{β} line broadening measurements. The measured widths of ArI lines, normalized to au electron density of 10^{16} cm^{-3} were compared with experimental data for analogous transitions in other noble atoms.
The experimental values of pressure broadening and shift coefficients of the ^{114}Cd 326.1 nm line perturbed by H_{2} and D_{2} are determined using a LIF technique and compared with theoretical values calculated from the impact theory.
Using a laser-induced fluorescence method a detailed analysis of profiles of the ^{114}Cd 326.1 nm line perturbed by neon and helium was performed which revealed deviations from the ordinary Voigt profile. These deviations are shown to be consistent with fits of experimental profiles to an asymmetric Voigt profile. Coefficients of the pressure broadening, shift and collision-time asymmetry are determined and compared with those calculated in the adiabatic approximation for different interaction potentials.
Profiles of the self-broadened 748.8 nm Ne line emitted from a glow discharge in neon in the pressure range between 0.8 and 100 Tr were measured using an improved experimental setup with pressure-scanned Fabry-Perot interferometer. First, line profiles were analysed using an ordinary Voigt procedure which yielded the Doppler widths decreasing with the increase in neon pressure. Using a speed-dependent Voigt profile it was shown that for the 748.8 nm line the correlation between the Doppler and collisional broadening plays an important role. However, the values of the pressure broadening and shift coefficients determined by the speed-dependent Voigt analysis were found to be only slightly different from those obtained by the ordinary Voigt analysis. A systematic error in the determination of perturber concentration in our previous investigation was corrected.
Electron densities and ion (gas) temperatures on the axis of an arc discharge plasma, produced at atmospheric pressure in a gas mixture of 95% helium and 5% argon, are determined at two arc currents. The evaluation of both main plasma parameters is based on line shape measurements, the ion temperature on the Doppler broadening of selected ArII lines, while the electron density on the Stark broadening of the hydrogen H_{β} line which appear in the spectrum due to hydrogen traces in the applied gases. The significance of reliable plasma diagnostics for determination of atomic structure data is discussed.
The profiles of argon perturbed components of the 5^{1}S_0-5^{3}P_1 line of the even-odd ^{113}Cd isotope were measured using a laser-induced fluorescence method. It was shown that the asymmetries of the profiles are due to both the collision-duration and line-mixing effects.
The interaction potentials for Zn_2 electronic states {1}_u and {0}_u^+ correlated with (4 {1}^P_1+4 {1}^S_0) asymptote in the long-range region (10-25) Å and the oscillator strength f for the absorption transition to these states are derived experimentally from a careful analysis of the self-broadened resonance 213.8 nm line of Zn. It is found that although the interatomic interactions at so long distances are dominated by resonance potential of the form C_3/R^3 resulting in the Lorentzian line shape, the parameter C_3 and thus f value significantly decrease with R decreasing. This effect proved to be a linear function of R^{-1} yielding the oscillator strength for the considered line f_0=1.456 ± 0.010 from R → ∞ extrapolation. This value seems to be the most accurate experimental result as yet and shows that the best theoretical values for this quantity are overestimated. It is suggested that the long-range behaviour of the potential energy curves observed here for the first time represents the effective potentials including dominating resonance interactions and a possible slight contribution of the dispersion interactions as well as the R-dependent spin-orbit interaction.
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