Absorption cross-sections for some atmospherically important molecules at the H atom Lyman-α wavelength (121.567 nm)

Abstract

Absolute values of gas-phase absorption cross-sections for some atmospherically important molecules (HCl, H 2O, H 2S, NH 3, H 2O 2, HNCO, CH 4, CH 3Cl, CH 2 Cl 2, CHCl 3 , CHF 2 Cl, CHBr 3 , CH 3CF 2Cl and CH 3CFCl 2) have been measured at the H atom Lyman-α wavelength (121.567 nm) employing narrow band ( Δλ=0.0006 nm) laser radiation generated by resonant third-order sum-difference frequency conversion. The present values can be used to access the uncertainty associated with Lyman-α absorption cross-section values derived from available literature absorption spectra which usually have been measured with quite different and sometimes with quite low spectral resolutions.