Far Infrared Measurability of HCl, OH, H2O2, HO2 and HOCl

Rotational transitions in a number of important stratospheric trace molecues can potentially be accurately measured by far infrared spectroscopy. HCl, OH, H2O2, HO2 and HOCl have large rotational constants due to the reduced mass of hydrogen plus other, heavier, constituents. The polyatomics in this group are all nearly symmetric prolate tops (NSPTs) having strong Q branches (b-type selection rules, ΔJ=0, ΔK=1) that are sufficiently compact to be seen as relatively sharp features in atmospheric spectra. All the molecules are characterized by reasonably large dipole moments (μb for the NSPTs) and small partition functions, if we consider only partitioning among the Ki for the NSPTs.