The Interstellar C-H Stretching Band Near 3.4 μm: Constraints on the Composition of Organic Material in the Diffuse ISM

Abstract

The spectra of objects suffering extinction by diffuse interstellar dust contain a broad feature centered at ~3300 cm −1 (~3.0 μm), attributed to O-H stretching vibrations, and/or a feature near 2950 cm −1 (3.4 μm) attributed to C-H stretching vibrations. The 2950 cm −1 feature can be attributed to C-H stretching vibrations in the -CH 2 - and -CH 3 groups of a fairly complex carbonaceous material containing aliphatic functional groups.