Issue 19, 2015

Activation of weak IR fundamentals of two species of astrochemical interest in the Td point group – the importance of amorphous ices

Abstract

New measurements are reported on the weak ν1 and ν2 fundamentals of frozen CH4, a solid of considerable astrochemical interest. Infrared spectra in the ν1 and ν2 regions are presented for three CH4-ice phases at 10–30 K with new absorption coefficients and band strengths to quantify the results. In contrast to the situation with the two crystalline phases of CH4, both ν1 and ν2 were seen clearly in methane's amorphous phase. To support our CH4 work, we also present new results for NH4SH, a component of Jupiter's atmosphere, showing that the ν2 vibration of NH4+ undergoes a dramatic loss of intensity during an amorphous-to-crystalline phase transition, but is regenerated in equally-dramatic fashion by radiation-induced amorphization of the sample. Results are compared to work recently published in this journal and elsewhere.

Graphical abstract: Activation of weak IR fundamentals of two species of astrochemical interest in the Td point group – the importance of amorphous ices

Article information

Article type
Paper
Submitted
15 Feb 2015
Accepted
13 Apr 2015
First published
16 Apr 2015

Phys. Chem. Chem. Phys., 2015,17, 12545-12552

Author version available

Activation of weak IR fundamentals of two species of astrochemical interest in the Td point group – the importance of amorphous ices

R. L. Hudson, P. A. Gerakines and M. J. Loeffler, Phys. Chem. Chem. Phys., 2015, 17, 12545 DOI: 10.1039/C5CP00975H

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