Pressure Induced Broadening of 35C10 and 16O2 Millimeter-Wavelength Rotational Transitions By N2

The importance of C10 as a catalytic species in stratospheric ozone depletion is of current interest. A product of the fast reaction of atomic chlorine and ozone, C10 distribution in the upper atmosphere has been modeled by Logan et al. [1]. Measurement of volume mixing ratios of stratospheric C10 is now performed by means of aircraft-based microwave emission spectrometers. The profiles obtained by analysis of the J=9/2-7/2, J = 13/2-11/2 and J = 15/2-13/2 transitions at 167 GHz, 241 GHz, and 278 GHz respectively are sensitive to the value of the pressure broadening parameter γ used in the collisional line shape function. Waters et al. [2] estimated γ = 3.8 MHz/mbar for C10 (μ = 1.24D) by linear interpolation of values for HF (γ = 4.5 MHz/mbar, μ = 1.8D) and CO (γ = 2.4 MHz/mbar, μ = 0.11D). This summary describes the determination of γ for C10 between 207K and 370K by N2 line broadening of the J=9/2-11/2 and J=13/2-15/2 transitions of v = 0 2Π3/2 35C10.