Rotationally inelastic rates for N2–N2 system from a scaling theoretical analysis of the stimulated Raman Q branch

Self‐broadened nitrogen isotropic Q(J) Raman linewidths have been inverted to obtain effective rotation–translation (R–T) state‐to‐state rate constants using the energy corrected sudden (ECS) formalism. These rate constants are discussed as a function of the rotational levels J and temperature T. Collisional Q(J) line shifts have been investigated by high‐resolution inverse Raman spectroscopy (IRS) over a wide temperature range. Semiclassical calculations lead to a clear understanding of their J and T dependence. This exhaustive study of both diagonal and off‐diagonal relaxation matrix elements has allowed us to calculate the collisionally narrowed Q branch at high pressure. New measurements of N2 Q branch at high pressure have been performed by IRS. The good agreement of ECS profiles with IRS data, for various pressures and temperatures, underlines the consistency of the present R–T ECS scaling analysis.

[1]  R. Leavitt,et al.  Cutoff‐free theory of impact broadening and shifting in microwave and infrared gas spectra , 1981 .

[2]  L. Bonamy,et al.  Overlapping effects and motional narrowing in molecular band shapes: Application to the Q branch of HDa) , 1977 .

[3]  J. Jonas,et al.  Raman study of vibrational dephasing in liquid CH3CN and CD3CN , 1977 .

[4]  U. Fano.  Pressure Broadening as a Prototype of Relaxation , 1963 .

[5]  G. Herzberg,et al.  Spectra of diatomic molecules , 1950 .

[6]  D. Lévesque,et al.  A molecular dynamics simulation of dephasing in liquid nitrogen , 1978 .

[7]  R. Gordon,et al.  Intermolecular Potentials and Infrared Spectra , 1971 .

[8]  J. Looney,et al.  Air broadening of the hydrogen halides—I. N2-broadening and shifting in the HCl fundamental , 1987 .

[9]  G. J. Rosasco,et al.  Line interference effects in the vibrational Q-branch spectra of N2 and CO , 1983 .

[10]  G. Levi,et al.  Temperature dependence of the vibrational phase relaxation in gases: Application to H2-rare gas mixtures , 1985 .

[11]  D. Robert,et al.  Short range force effects in semiclassical molecular line broadening calculations , 1979 .

[12]  R. J. Hall.  Coherent Anti-Stokes Raman Spectroscopic Modeling For Combustion Diagnostics , 1983 .

[13]  H. Friedmann,et al.  THEORY OF SHIFTS OF VIBRATION-ROTATION LINES OF DIATOMIC MOLECULES IN NOBLE GAS MATRICES. INTERMOLECULAR FORCES IN CRYSTALS. , 1965 .

[14]  S. Green.  On the amount of information in rotational relaxation experiments with application to microwave transient T1 and T2 rates , 1978 .

[15]  B. Lavorel,et al.  Self-density frequency shift measurements of Raman N2 Q-branch transitions , 1987 .

[16]  M. Coltrin,et al.  Theoretical and experimental studies of high-resolution inverse Raman spectra of molecular nitrogen at 1-10 atm , 1987 .

[17]  A. Ben-Reuven.  Impact Broadening of Microwave Spectra , 1966 .

[18]  R. D. Haun,et al.  Laser applications , 1968, IEEE Spectrum.

[19]  R. Lord.  Vibrational spectra and structure : Volume 7, J.R. Durig, ed., Elsevier Scientific Publishing Co., Amsterdam, 1978, xv + 388 pages. Dfl. 146,00, $63.50. , 1976 .

[20]  A. Eckbreth,et al.  Pressure-induced narrowing of the cars spectrum of N2☆ , 1980 .

[21]  H. Rabitz,et al.  Collision dynamical information from pressure broadening measurements: Application to carbon monoxide , 1983 .

[22]  H. Rabitz,et al.  Direct inversion of high overtone collision broadened linewidths in the HCl-HCl system: Rotationally inelastic rates for highly vibrationally excited molecules , 1981 .

[23]  A. Harvey.  Chemical applications of nonlinear Raman spectroscopy , 1981 .

[24]  R. J. Hall,et al.  Application of the rotational diffusion model to gaseous N2 CARS spectra , 1982 .

[25]  Herbert Walther,et al.  Laser Spectroscopy IV , 1979 .

[26]  A. Owyoung,et al.  Coherent Raman gain spectroscopy using CW laser sources , 1978 .

[27]  G. Millot,et al.  Rotational collisional line broadening at high temperatures in the N2 fundamental Q-branch studied with stimulated Raman spectroscopy , 1986 .

[28]  G. Millot,et al.  A rotational thermalization model for the calculation of collisionally narrowed isotropic raman scattering spectra - application to the SRS N2 Q-branch , 1986 .

[29]  G. Millot,et al.  Study of rotational relaxation fitting laws from calculations of SRS N2 Q-branch , 1987 .

[30]  K. Lawley.  Dynamics of the excited state , 1982 .

[31]  R. Amos.  SCF and CI calculations of the one-electron properties, polarizabilities and polarizability derivatives of the nitrogen molecule , 1980 .

[32]  G. Brocks,et al.  Infrared spectra of the Van der Waals molecule (N2)2 , 1985 .

[33]  M. E. Rose.  Elementary Theory of Angular Momentum , 1957 .

[34]  M. Alexander,et al.  An adiabatically corrected sudden approximation for rotationally inelastic collisions between polar molecules , 1979 .

[35]  A. Depristo.  Collisional influences on vibration--rotation spectral line shapes: A scaling theoretical analysis and simplification , 1980 .

[36]  R. Palmer,et al.  Studies of nitrogen self-broadening at high temperature with inverse Raman spectroscopy , 1986 .

[37]  R. Farrow,et al.  Calculation of collisionally narrowed coherent anti-Stokes Raman spectroscopy spectra. , 1985, Optics letters.

[38]  J. Bonamy,et al.  Vibrational dephasing effects and motional narrowing in the isotropic Raman Q branch of HD , 1978 .

[39]  M. Péalat,et al.  Precision of multiplex CARS temperature measurements. , 1985, Applied optics.

[40]  Jeanine Bonamy,et al.  Simplified models for the temperature dependence of linewidths at elevated temperatures and applications to CO broadened by Ar and N2 , 1984 .

[41]  H. Rabitz,et al.  Quantum number and energy scaling for nonreactive collisions , 1979 .

[42]  S. Barton,et al.  A polynomial energy-gap model for molecular linewidths , 1985 .