Regularities and similarities in plasma broadened spectral line widths (Stark widths)

Regularities and similarities in plasma broadened line widths have been studied by a comprehensive analysis of existing experimental data. Regularities are expected on the basis of general atomic structure considerations, and should be evident for spectral series, for corresponding transitions in homologous atoms and in isoelectronic sequences. Furthermore, similarities of line widths are expected for multiplets, supermultiplets and, to a lesser degree, for transition arrays. A comprehensive examination of literature data has been undertaken, which shows generally a close adherence of the measured data to the expected regularities. A few notable exceptions are also given.     

Anomalous resonance effects in collision broadened spectral line widths

Calculations of self broadened DF vibration-rotation line widths and of widths of DF and HF broadened by each other have been performed using the Anderson theory. The calculations include effects of inexact resonances in the upper states of the fundamental band and also include dipole-dipole, dipole-quadropole and the quadropole-quadropole terms in the multipolar expansion. A qualitative discussion of the results is given.     

Air-broadened line widths of methane at atmospheric temperatures

Air-broadened half-widths of lines R(0), R(1) and R(2) in the ν₃-fundamental of ¹²CH₄ have been measured at 200°K, 250°K and 300°K.     

Temperature dependence of atomic spectral line widths in a plasma

We investigated here temperature dependence of Stark widths for neutral atom spectral lines in order to find a more precise method for scaling with temperature than sometimes used dependence T^-1/2, which is often inadequate particularly for Stark broadening of neutral emitter lines. We found here an analytical scaling with temperature within simplified semiclassical approaches of Freudenstein and Cooper and Dimitrijević and Konjević. For analysis of the temperature dependence, lines of HeI were used.     

Pressure broadened line widths of BrCN in the microwave region

The line widths of cyanogen bromide (BrCN) have been measured at room temperature (305 K) by using a double modulation microwave spectrograph. The self-broadening of two quadrupole hyperfine lines of the transition J = 3 → 4 has been measured. The foreign gas broadening by OCS, CO₂, N₂, CH₃CN, CH₃I, HCHO and CH₃CHO molecules has been measured only for the intense line at 32·957 GHz. These measured line widths have been compared with the calculated line widths using Anderson [6] as well as Murphy and Boggs [8] theories of pressure broadening.     

Vibrational relaxation and line widths in liquids dephasing by intermolecular forces

A theory of vibrational relaxation in liquids is presented in which the vibrations are loosely coupled to a bath or lattice of molecular translations and rotations by intermolecular forces. Using the second-order perturbation expressions familiar from magnetic resonance the secular contribution to the line width is calculated. Different coupling paths are considered and expressions given for the line widths in a liquid mixture in terms of number densities and diffusion coefficients valid when reorientation is slow and translation diffusional.     

激光诱导击穿光谱定量分析中的分析线自动选择方法

为了实现激光诱导击穿光谱分析中的分析线自动选择,定义了元素发射谱线的相对强度比(RDTIR)、波长偏差(WDDT)两个参数,并据此对检测谱线进行筛选,通过设定合理的阈值,剔除自吸收和干扰严重的谱线。通过对高合金钢(GBW01605)实验数据的分析,分别选定了样品中主要元素铁、铬、镍、锰、铜的分析线,选线结果符合谱线的选取原则。     

Measurements of nitrogen-broadened line widths of acetylene at low temperatures

Spectral transmittance measurements have been performed on N₂-broadened lines of C₂H₂ in the 7.53 μm region at 153 and 200 K with a spectral resolution of 0.06 cm^-1. The line widths have been determined as functions of temperature and rotational quantum number using line-by-line comparison of theoretical and experimental values of spectral transmittance.     

On the variation of spectral line widths within stark-broadened multiplets

The Stark broadening of isolated ion lines is considered in the electron impact approximation. It is shown by an elementary formulation of the theory that, under certain plasma conditions, situations may arise in complex atoms where a relatively small number of collision-induced transitions predominate in the broadening, and consequently where appreciable variations of spectral line width are obtained within multiplets. Such lines are then particularly suitable for application of the Stark-broadening mechanism as a means of studying atomic structure and collision physics.     

The influence of finite line widths on parity mixing in muonic atoms

The parity mixing due to parity-violating neutral currents in muonic atoms is discussed in the case where the line widths of two mixing states are comparable with or larger than their energy difference. It is shown that the line widths give rise to a considerable reduction of the parity mixing effects.     

The temperature dependence of the Rayleigh line wing and depolarized combinational scattering line widths in critical mixtures

It has been experimentally found that at approaching the critical temperature of the exfoliating mixture carbon-disulfide-ethanol the widths of the Rayleigh line wing and the depolarized combinational scattering line drastically decrease. The same phenomenon was observed for 3 nitrobenzene combinational line scattering in a nitrobenzene—n-hexane mixture.     

Collision-broadened line widths of tetrahedral molecules—I. Theoretical formulation

A theoretical formulation is presented within the framework of Anderson-Tsao- Curnutte theory for calculating the half-widths of spectral lines belonging to tetrahedral molecules. The importance of tetrahedral symmetry in the change distribution and in the wave functions is emphasized. Expressions for the interruption functions S₂(b) have been derived for octopole-dipole, octopole-quadrupole, octopole-octopole, octopole-hexadecapole, hexadecapole- hexadecapole, anistropic dispersion interactions as well as for an assumed overlap interaction potential. The earlier theoretical work of Tejawni and Yamamoto and Hirono is shown to be inappropriate for molecules of tetrahedral symmetry.     

Diode laser measurements of CO line widths at planetary atmospheric temperatures

Hydrogen-broadened half-widths and nitrogen-broadened half-widths of eight lines between P(1) and P(15) in the CO fundamental have been measured at several temperatures between 94 and 298 K using a tunable diode laser spectrometer and the sweep integration technique.     

Effect of hydrogen bonding on the Rayleigh and Raman line widths

A study was made of the broadening of the Rayleigh-scattering line of nitromethane solutions in chloroform, benzene, acetone, and CCl₄. The scattering line contracts in the chloroform solutions but is unaffected in the other solutions. The results are attributed to a decrease in the ability of the molecules to rotate as a result of the formation of nitromethane-chloroform associations; A pronounced contraction of the 1591 cm^–1 line is observed in the Raman spectra of the chloroform solution. The other lines studied displayed no appreciable contraction in the transition from the pure liquid to the solutions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 11, pp. 7–11, November, 1970.     

Relaxation times and line widths of isotopically-substituted nitroxides in aqueous solution at X-band

Optimization of nitroxides as probes for EPR imaging requires detailed understanding of spectral properties. Spin lattice relaxation times, spin packet line widths, nuclear hyperfine splitting, and overall lineshapes were characterized for six low molecular weight nitroxides in dilute deoxygenated aqueous solution at X-band. The nitroxides included 6-member, unsaturated 5-member, or saturated 5-member rings, most of which were isotopically labeled. The spectra are near the fast tumbling limit with T₁∼T₂ in the range of 0.50–1.1 μs at ambient temperature. Both spin–lattice relaxation T₁ and spin–spin relaxation T₂ are longer for ¹⁵N- than for ¹⁴N-nitroxides. The dominant contributions to T₁ are modulation of nitrogen hyperfine anisotropy and spin rotation. Dependence of T₁ on nitrogen nuclear spin state m_I was observed for both ¹⁴N and ¹⁵N. Unresolved hydrogen/deuterium hyperfine couplings dominate overall line widths. Lineshapes were simulated by including all nuclear hyperfine couplings and spin packet line widths that agreed with values obtained by electron spin echo. Line widths and relaxation times are predicted to be about the same at 250 MHz as at X-band.     

Effect of collision-induced phase-shifts on the line widths and line shifts of CO2-Ar system

The theoretical calculation of line widths and line shifts for CO₂-Ar system is computed by the Mehrotra-Boggs theory. It is shown for this system that the phase shift effect is very important at large values of |m| wherem is the value of rotational quantum numberJ in the lower vibrational state. It is also pointed out that the Salesky-Korff theory is the same as the Mehrotra-Boggs theory.     

Autler-Townes triplet spectroscopy: An analytical approach

In Ref. [Opt. Commun. 273, 464-472 (2007)] we studied Autler-Townes triplet spectrum. The presented results were not easy to display in readable and transparent form because the operating physical mechanism is hidden by the algebraic complexity. Here we present analytical results in a very simple and interpretable form. These results enable us to get a new insight into the interference mechanism in a quiet clear manner. We have given a new dimension to the problem in calculating the emission spectrum by state vector method. New estimates are given to measure the spectroscopic parameters in analytical fashion. The interference mechanism in the excited three decaying dressed state is effectively explored which splits the single Lorentzian peak to three spectral components due to two dark lines. The width of each spectral component can be narrowed to up to 0.05Γ.     

Evaluation of spectral line profile from relative widths of Fabry- Perot interferograms

A graphical method for deconvolution of spectral line profiles scanned by a Fabry-Perot interferometer from relative widths is described. The relation between the normalized intensity and relative width is derived. All calculations have been carried out assuming that the overall surface defects function can be approximated by Gaussian function, and the contribution of broadening due to the scanning aperture is negligible.     

Measurement of line widths of CO of planetary interest at low temperatures

Self-broadened, air-broadened and CO₂-broadened half-widths of lines R(0) through R(0) in the CO fundamental have been measured at 100°K (self-broadening only), 200°K, 250°K and 300°K using the Ladenburg-Reiche curve-of-growth. The relation $\text{γ}{}^{\mathrm{°}}{}_{\mathrm{m}}\text{(T)}\text{γ}{}^{\mathrm{°}}{}_{\mathrm{m}}\text{(300°K)}\text{=(}\text{300}\text{T}\text{)}{}^{0.75}$, which we found previously for the nitrogen-broadened half-widths of R(0), R(8) and R(16), is shown to be valid for all of the line widths measured in the present study.