PRESSURE BROADENING AND SHIFT COEFFICIENTS FOR THE BAND OF 12 C 16 O 2 NEAR 6348 cm -1 D. CHRIS BENNER and V MALATHY DEVI Department of Physics, The College of William and Mary Williamsburg, VA LINDA R. BROWN, CHARLES E. MILLER and ROBERT A. TOTH Jet Propulsion Laboratory, California Institute of Technology 4800 Oak Grove Dr., Pasadena, CA

Experimental conditions of spectra Temp Broadening Total Pressure Path length (C) Gas (Torr) (m) Self Self Self Self Self Self Self Self ______________________________________________________

Multispectrum Techniques of Fit 8 Self broadened spectra fit simultaneously Entire band fitted in one solution Zero pressure positions of lines constrained to ν = E′-E″ E=G+BJ(J+1)-D[J(J+1)] 2 +H[J(J+1)] 3 Solve for G′-G″, B′, D′, H′, B″, D″ & H″, not positions

Multispectrum Techniques of Fit Intensities constrained to Solve for S v, a 1, a 2 and a 3 instead of individual line intensities

Multispectrum Techniques of Fit Self broadened Lorentz halfwidths unconstrained Self induced pressure shifts unconstrained Rosenkranz Line Mixing unconstrained or Relaxation matrix elements connecting neighboring lines in each branch unconstrained Position and intensity constraints reduce substantially the number of parameters determined Position constraints improve pressure shifts Intensity constraints reduce correlations with widths Constraints help resolve blends

BAND OF 12 C 16 O 2

Lorentz line shape of N line profiles as a function of ω (cm -1 ) described by Levy et al ω and ω o and ρ are N x N diagonal matrices Diagonal elements are: ω (jj) = wavenumber ω o (jj) = zero pressure line position ρ (jj) = number density of the transition lower states Off-diagonal elements are: ω (jk) = ω o (jk) = ρ (jk) = 0 W is the “relaxation matrix” to include line mixing Χ is a 1 x N matrix S is the transition intensity T is the transpose

Relaxation matrix off-diagonal elements W= Relaxation Matrix W jj is function of Lorentz widths and pressure shifts W jk (line mixing coefficients = off diagonal elements) W jk and W kj related by energy density ρ calculated via Boltzmann terms where E is lower state energy C 2 is 2 nd radiation constant = K/cm where

BAND OF 12 C 16 O 2

Comparison of self- and air broadening coefficients to values in HITRAN04

Comparison of spectral line parameters

BAND OF 12 C 16 O 2

Conclusions For 12 C 16 O 2 self broadening in the band at 6348 cm -1 : Line mixing is observed in P and R branches P and R branch line mixing does not depend solely upon the lower state HITRAN widths are good to 4% Speed dependence is observed and almost constant from line to line (0.1), but is less important than line mixing Future will include two other bands and include temperature dependence, and broadening by air, N 2, O 2 and Ar