Collisional Broadening Research Articles

Collisional Broadening within a Hadronic Transport Approach

We explore the emergence of the collisional broadening of hadrons under the influence of different media using the hadronic transport approach SMASH (Simulating Many Accelerated Strongly interacting Hadrons), which employs vacuum properties and contains no a priori information about in-medium effects. In this context, we define collisional broadening as a decrease in the lifetime of hadrons, and it arises from an interplay between the cross-sections for inelastic processes and the available phase space. We quantify this effect for various hadron species, in both a thermal gas in equilibrium and in nuclear collisions. Furthermore, we distinguish the individual contribution of each process and verify the medium response to different vacuum assumptions; we see that the decay width that depends on the resonance mass leads to a larger broadening than a mass-independent scenario.

Estimation of Collisional Broadening and Shift for Argon Lines at 811.5 nm and 912.3 nm in Pure Gas and Ar–Ne Mixture

Estimation of Collisional Broadening and Shift for Argon Lines at 811.5 nm and 912.3 nm in Pure Gas and Ar–Ne Mixture

Collisional Broadening of Spectral Lines in Slow Atomic Collisions

Collisional Broadening of Spectral Lines in Slow Atomic Collisions

Non-perturbative Determination of the Collisional Broadening Kernel and Medium-induced Radiation in QCD Plasmas

Non-perturbative Determination of the Collisional Broadening Kernel and Medium-induced Radiation in QCD Plasmas

Errors of Pure Rotational Raman Lidar Absolute Calibration Due to Collisional Line Broadening

Errors of Pure Rotational Raman Lidar Absolute Calibration Due to Collisional Line Broadening

H2O Collisional Broadening Coefficients at 1.37 µm and Their Temperature Dependence: A Metrology Approach

We report self- and air collisional broadening coefficients for the H2O line at 7299.43 cm−1 and corresponding temperature coefficients for a temperature range spanning 293–573 K. New laser spectroscopic setups specifically designed for this purpose have been developed and are described. The line parameters reported here are in good agreement with those values reported in the HITRAN 2020 database, but the uncertainties have been reduced by factors of about 4, 1.3 and 4.4 for the self-broadening coefficient, air broadening coefficient and the temperature exponent of air broadening, respectively. Further, we combined our measurement approach with metrological data quality objectives, addressing the traceability of the results to the international system of units (SI) and evaluated the uncertainties following the guide to the expression of uncertainty in measurement (GUM).

Collisional Broadening of Vibrational-Rotational CO2 Lines by Buffer Gases

Unsaturated absorption coefficients in pure CO2 and binary mixtures of CO2 with buffer gases Mj (He, Ar, Kr, Xe, N2, O2, CO, N2O, 13C16O2) were measured with a tunable CO2 laser at the central frequencies of the R(8), R(22), R(34), P(8), P(22), and P(36) CO2 spectral lines of the 1000–0001 transition at a temperature of 300–700 K. A technique is described and the coefficients of self-broadening and broadening of CO2 spectral lines by a buffer gas Mj are calculated. It is shown that the efficiency of the CO2 interaction with diatomic and triatomic molecules is determined by the electric moment; in the case of inert gases, the mass factor plays the major role. It is ascertained that the temperature dependences of the collisional broadening of CO2 spectral lines can be highly accurately approximated by power functions with two different exponents.

Collisional Broadening of CO2 Transition Lines 1000–0001 by Inert Gas Atoms at 300–700 K

Using a tunable CO2 laser, unsaturated absorption coefficients in pure CO2 and binary CO2 gas mixtures with inert gases He, Ar, Kr, and Xe in a 1 : 2 ratio at 100 Torr were measured at the central frequencies of the R(8), R(22), P(8), P(22), and P(32) CO2 spectral lines of the 1000-0001 transition at 300–700 K. The coefficients of the collisional broadening of the CO2 spectral lines by He, Ar, Kr, and Xe are determined. The obtained temperature dependences of the collisional broadening coefficients are approximated by power functions with two different degrees.

Collisional Broadening of CO2 1000–0001 Transition Lines by O2 and N2 in the Range 300–700 K

Unsaturated absorption coefficients are measured using a tunable CO2 laser in pure CO2 and CO2:O2 = 1:2 and CO2:N2 = 1:2 gas mixtures at the central frequencies of the R(8), R(22), P(8), P(22), and P(36) CO2 1000–0001 transition lines under a pressure of 100 Torr in the temperature range 300–700 K. The collisional broadening coefficients of the CO2 spectral lines by O2 and N2 are obtained. The temperature dependences of these coefficients are approximated by power functions with two different exponents.

Collisional transitions between HFS states of antiprotonic 3He in the presence of microwave radiation

We consider collisional effects on the transitions between HFS states of \(({\bar{\rm p}\,^3{\rm He}}^+)\) in the presence of microwave radiation. Cross sections and rates of collisional HFS transition, density shifts and broadening of M1 spectral lines are calculated within the approach developed previously for \(({\bar{\rm p}\,^4{\rm He}}^+)\). The values averaged over thermal motion are used in the quantum master equation for the density matrix of HFS states in the microwave field. At the target density 3 × 1020 cm − 3 and T = 6 K, partial rates of the single spin-flip transition in \((\bar{{\rm p}}\,^3\mathrm{He}^+)\) are ∼1 · 106 s − 1. Effective relaxation rates by considering the kinetics are approximately twice more. At the same conditions collisional shifts of the M1 spectral lines are ≤ 4 kHz, collisional broadening of the lines is ≃ 0.5 MHz. The total width of the line J − − + → J + − + at t d = 350 ns is 2.4 MHz allowing for collisional and Fourier broadenings. Maximum MW resonance signal in 3He is about 0.5 of that one in 4He.

Measurements of Collisional Broadening Coefficients by Infrared Polarization Spectroscopy

We present measurements of collisional broadening coefficients, obtained at atmospheric pressure, by polarization spectroscopy. Using tunable single mode laser radiation at approximately 2 microm, high-resolution infrared polarization spectra were recorded for CO2-Ar and CO2-He binary mixtures. The recorded polarization spectra were fitted with a Lorentzian cubed function form to obtain the broadening coefficients. The full-width at half-maxima (FWHM) collisional broadening rates of CO2 by Ar and He, for the R14 (12 degrees1<--00 degrees0) line, have been determined to be 0.161+/-0.018 cm-1 atm-1 and 0.1823+/-0.0032 cm-1 atm-1, respectively.

The Effect of Collisional Line Broadening on the Spectrum and Fluxes of Thermal Radiation in the Lower Atmosphere of Venus

The absorption spectrum and thermal radiation fluxes are calculated for the lower atmosphere of Venus in the far-wing approximation based on the theory of the collisional broadening of spectral lines. The results are in good agreement with the available experimental data. An outgoing thermal radiation flux is about 2.6 W/m2 near the planetary surface. This indicates that free convection significantly contributes to the thermal balance of the lower troposphere. The fluxes obtained in this study were compared to those calculated on the basis of empirical models of the spectral line profile. It was shown that the far wings of the CO2 lines considerably affect the radiative transfer in the transparency windows. This effect becomes weaker when the contribution of the absorption of minor constituents, primarily water vapor, increases. The profiles of absorption lines of minor constituents do not influence the thermal radiation fluxes.

Spin-Dependent Transport in Heavily Mn-Doped GaAs II: Effect of Collisional Broadening

We have studied theoretically electrical transport in a new ferromagnetic semiconductor (Ga,Mn)As by taking into account spin disorder and impurity scatterings. Especially we have investigated the effect of the collisional broadening on the spin disorder scattering due to the strong interaction of charge carriers with the Mn ions. By using Zubarev’s double-time Green’s functions we derive an estimate for the carrier lifetime in the case of strongly broadened band states. The collisional broadening results in a Lorenzian-type spectral function, which in turn broadens the resistivity peak near the Curie temperature as compared to the conventional d-function-type spectral function. This improves the fit of the calculated results to the experimental resistivity data in Ga0.947Mn0.053As.

Collisional Broadening Coefficients in the ν4 Band of NH3 Perturbed by He and Ar

He- and Ar-broadening coefficients have been measured for 62 absorption lines of NH3 at 296 K in the P branch of the ν4 band, using a high-resolution Fourier transform spectrometer. These lines with J values ranging from 2 to 9 are located in the spectral range 1450–1600 cm−1. The collisional widths are obtained by modeling each absorption line with a Voigt profile. The results are compared with those calculated from a semiclassical model including a second-order Legendre polynomial expansion with adjustable parameters for the intermolecular potential. The experimental and theoretical broadening coefficients have the same behavior with J and K: they roughly decrease as J increases and, except for K = 0, increase with K for a given J value. These variations are small for NH3–He and more significant for NH3–Ar. The calculations give a satisfactory agreement with the data for both perturbers but exaggerate the K dependence of the broadening coefficients, especially for J ≥ 7.

Collisional Broadening of the Na-D Lines by MolecularGases

The experimental investigations devoted to the Na-D spectral linebroadening by molecular gases are reviewed. The theoreticalinterpretation of the data within the framework of the classicaltheory of atomic spectral line broadening is given. The effect ofadiabatic and diabatic collisions on the shape of both impact andquasi-static spectral-line wings is discussed. The different forms ofspectral-line shape representation and the connections between themare considered. The experimental cross-sections of the Lorentzianbroadening of the Na-D lines by molecules are presented and comparedwith the theoretical ones. The problem of restoration of the adiabaticinteraction potentials from quasi-static wing profiles is noted. TheC6, C12 parameters of theeffective atom-molecular potentials of the Lennard-Jones 12-6 form,restored on quasi-static wing profiles, are presented.

Spectral Functions and Collisional Broadening in Semiconductor Ultra-High Field Transport

Spectral Functions and Collisional Broadening in Semiconductor Ultra-High Field Transport

Anomalous Pressure Dependence of Infrared Spectra Due to the Combination of Collisional Broadening and Instrument Resolution

The combination of collisional line broadening and limited instrumental resolution can have peculiar and unexpected effects on the intensities of infrared spectra. An illustrative example is provided by the series of Q branches in the v7 band of ethane. Conventional FT-IR spectra, with a resolution of ∼0.25 cm−1, show a dramatic increase in the absorbance of these branches as a function of increasing N2 partial pressure, an effect which could be construed as collisional narrowing. In contrast, high-resolution diode laser spectroscopy reveals a monotonie increase in branch width (0.14 cm−1/atm), and a concomitant decrease in intensity, as the N2 pressure is raised. The present work shows that absorption measurement of the inherently very narrow ethane Q branches with limited instrumental resolution and collisional line broadening conspire to give the appearance that the absorbance increases with N2 pressure. This effect in general, as well as its implications for the use of FT-IR spectroscopy to measure molecular concentrations in gaseous mixtures, is discussed.

Monte Carlo algorithms for collisional broadening and intracollisional field effect in semiconductor high-field transport

We present a computational scheme which can be readily included in a standard Monte Carlo code to give quantitative estimates of the intracollisional field effect (ICFE) or of collisional broadening (CB). The central quantity in our theory is the joint spectral density K(εi, εf ) which connects the initial and final kinetic energy of a carrier in a scattering event. Crucial approximations, connected with the algorithms which model the joint spectral densities obtained from the appropriate Dyson equation, are clearly stated and discussed. Numerical results for a simple model semiconductor are provided for illustrative purposes. These show that both ICFE and CB lead to a significant increase of carriers in the high-energy tail of the distribution function.

Theory for the Polarizability Function of an Electron Layer in the Presence of Collisional Broadening Effects and Its Experimental Implications

The polarizability function of a two-dimensional electron layer submerged in a threedimensional dielectric material and interacting with a random distribution of static charged impurity centers is calculated. Scattering and screening are treated self-consistently and each affects the other. The resultant scattering time is found to depend on the impurity density ${N}_{i}$ through the ${(a{N}_{i}+b{{N}_{i}}^{2})}^{\ensuremath{-}1}$ law which has been observed experimentally in silicon inversion layers. The theory is in good agreement with the experimental findings on the parameters $a$ and $b$.

Collisional Broadening of Level Crossing Singnals in 62P3/2 and 72P3/2 State of 133Cs Atom

Collisional Broadening of Level Crossing Singnals in 6²P_3/2 and 7²P_3/2 State of ¹³³Cs Atom