Infrared Spectra and Optical Constants of Astronomical Ices: II. Ethane and Ethylene

TL;DR

This paper provides new measurements of the optical constants and refractive indices of ethane and ethylene ices at various temperatures, aiding the interpretation of infrared spectra of ices on celestial bodies.

Contribution

It presents comprehensive optical constants for ethane and ethylene ices, including temperature-dependent data, enhancing spectral analysis of extraterrestrial ices.

Findings

Optical constants for ethane and ethylene ices are measured across multiple phases and temperatures.

New refractive index measurements at 670 nm are provided for both ices.

Results are compared with previous studies and made available electronically.

Abstract

Infrared spectroscopic observations have established the presence of hydrocarbon ices on Pluto and other TNOs, but the abundances of such molecules cannot be deduced without accurate optical constants (n, k) and reference spectra. In this paper we present our recent measurements of near- and mid-infrared optical constants for ethane (C$_2$H$_6$) and ethylene (C$_2$H$_4$) in multiple ice phases and at multiple temperatures. As in our recent work on acetylene (C$_2$H$_2$), we also report new measurements of the index of refraction of each ice at 670 nm. Comparisons are made to earlier work where possible, and electronic versions of our new results are made available.