Infrared absorption bands of α- and β-pinenes in the 8–14-μm atmospheric window region

Abstract

There are bands in the 8 -14-microm atmospheric window region of the gas phase IR spectra of alpha- and beta-pinenes that are intense enough to allow theoretically the naturally occurring terpenes to be determined in the 100- ppbv level at 1-km path lengths. Because of the broadness of the bands, however, and the relatively intense atmospheric background at their frequencies of 786.5 cm(-1) and 880 cm(-1), respectively, practical concentration limits for the use of the bands are probably not better than about 1-10 ppmv. Both type C bands have 4-cm(-1)Q branches which fall at frequencies which are essentially free of any major atmospheric fine structure bands.