Physical and spectroscopic properties of pure C2H4 and CH4:C2H4 ices

[EN] Physical and spectroscopic properties of ices of C2H4 and CH4:C2H4 mixtures with 3:1, 1:1 and 1:3 ratios have been investigated at 30 K. Two laboratories are involved in this work. In one of them, the density and refractive index of the samples have been measured by using a cryogenic quartz microbalance and laser interferometric techniques. In the other one, IR spectra have been recorded in the near- and mid-infrared regions, and band shifts with respect to the pure species, band strengths of the main bands, and the optical constants in both regions have been determined. Previous data on ethylene and the mixtures studied here were scarce. For methane, both the wavenumbers and band strengths have been found to follow a regular pattern of decrease with increasing dilution, but no pattern has been detected for ethylene vibrations. The method employed for the preparation of the samples, by vapour deposition under vacuum, is thought to be adequate to mimic the structure of astrophysical ices. Possible astrophysical implications, especially by means of the optical constants reported here, have been discussed.This work has been funded by the Ministerio de Ciencia y Competitividad (MINECO) of Spain under grants FIS2013-48087-C2-1P, FIS2013-48087-C2-2P and AYA2015-71975-REDT 'Polvo Cosmico' by the Ministerio de Ciencia e Innovacion of Spain under grant CDS2009-00038 and by the European Research Council project ERC-2013-Syg 610256 'Nanocosmos'. GM acknowledges MINECO PhD grant BES-2014-069355. Our skillful technicians C. Santonja, M. A. Moreno, A. Gonzalez and J. Rodriguez are also gratefully acknowledged.Molpeceres, G.; Satorre Aznar, MÁ.; Ortigoso, J.; Zanchet, A.; Luna Molina, R.; Millán Verdú, C.; Escribano, R.... (2017). Physical and spectroscopic properties of pure C2H4 and CH4:C2H4 ices. Monthly Notices of the Royal Astronomical Society. 466(2):1894-1902. https://doi.org/10.1093/mnras/stw3166S18941902466