No compelling evidence for clathrate hydrate formation under interstellar medium conditions over laboratory timescales

TL;DR

This paper critically examines recent claims of methane and CO2 clathrate formation under interstellar medium conditions, arguing that the evidence is not compelling and that laboratory timescales may not reflect true ISM processes.

Contribution

It challenges previous experimental interpretations of clathrate formation in the ISM, emphasizing the need for caution in extrapolating laboratory results to space environments.

Findings

No definitive evidence of clathrate formation under ISM conditions

Potential pitfalls in interpreting infrared spectroscopy data

Laboratory timescales may not match interstellar processes

Abstract

A recent article reported experimental observations of methane and CO2 clathrate formation at conditions similar to the interstellar medium (ISM), namely 10-30 K and 10-10 mbar. The authors conducted time-dependent reflection-absorption infrared spectroscopy (RAIRS) of vapor-deposited H2O:CH4 and H2O:CO2 mixtures and interpreted new blue and red -shifted peaks from those of trapped CH4 and CO2 in amorphous ice, respectively, as indicative of clathrate formation. In this Letter to the Editor, we point out potential pitfalls and caution against the implications drawn for the ISM.