engleski

Sulphur-bearing species in molecular clouds

Using density functional theory methods we studied several molecules that could help in the solution of the missing sulphur problem in dense clouds and circumstellar regions, as well as in the clarification of the sulphur chemistry in comets. We calculated infrared spectra of the following molecules: the trimer (CH2S)3 and the tetramer (CH2S)4 of thioformaldehyde, pentathian S5CH2, hexathiepan S6CH2, thiirane C2H4S, trisulfane HSSSH, and thioacetone (CH3)2CS. We suggest that some of unidentified spectral features measured by Infrared Space Observatory in several active galactic nuclei and starburst galaxies could be caused by (CH2S)3, (CH2S)4, and thiirane C2H4S. The objects whose unidentified infrared features we com- pare with calculated bands are NGC 253, M82, NGC 1068, Circinus, Arp 220, 30 Doradus, Orion KL, and Sgr B2.

astrophysical molecules; sulphur species; infrared spectra; radio spectra; densty functional theory

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