Qualitative observation of reversible phase change in astrochemical ethanethiol ices using infrared spectroscopy

S Pavithraa; R R J Methikkalam; P Gorai; J-I Lo; A Das; B N Raja Sekhar; T Pradeep; B-M Cheng; N J Mason; B Sivaraman

doi:10.1016/j.saa.2017.01.023

Qualitative observation of reversible phase change in astrochemical ethanethiol ices using infrared spectroscopy

Spectrochim Acta A Mol Biomol Spectrosc. 2017 May 5:178:166-170. doi: 10.1016/j.saa.2017.01.023. Epub 2017 Jan 12.

Authors

S Pavithraa¹, R R J Methikkalam², P Gorai³, J-I Lo⁴, A Das³, B N Raja Sekhar⁵, T Pradeep², B-M Cheng⁴, N J Mason⁶, B Sivaraman⁷

Affiliations

¹ Atomic Molecular and Optical Physics Division, Physical Research Laboratory, Ahmedabad, India.
² Department of Chemistry, Indian Institute of Technology-Madras, Chennai, India.
³ Indian Centre for Space Physics, Kolkata, India.
⁴ National Synchrotron Radiation Research Center, Hsinchu, Taiwan.
⁵ B-1, Indus-1, Atomic Molecular Physics Division, BARC at RRCAT, Indore, India.
⁶ Department of Physical Sciences, The Open University, Milton Keynes, UK.
⁷ Atomic Molecular and Optical Physics Division, Physical Research Laboratory, Ahmedabad, India. Electronic address: bhala@prl.res.in.

PMID: 28187314
DOI: 10.1016/j.saa.2017.01.023

Abstract

Here we report the first evidence for a reversible phase change in an ethanethiol ice prepared under astrochemical conditions. InfraRed (IR) spectroscopy was used to monitor the morphology of the ice using the SH stretching vibration, a characteristic vibration of thiol molecules. The deposited sample was able to switch between amorphous and crystalline phases repeatedly under temperature cycles between 10K and 130K with subsequent loss of molecules in every phase change. Such an effect is dependent upon the original thickness of the ice. Further work on quantitative analysis is to be carried out in due course whereas here we are reporting the first results obtained.

Keywords: Astrochemistry; Infrared spectroscopy; Reversible phase change.