Mid-IR band strength, density, refractive index, and thermal evolution study for solid CH2DOH pure and in astrophysical relevant mixtures

C Scirè; R G Urso; D Fulvio; G A Baratta; M E Palumbo

doi:10.1016/j.saa.2019.04.021

Mid-IR band strength, density, refractive index, and thermal evolution study for solid CH₂DOH pure and in astrophysical relevant mixtures

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Aug 5:219:288-296. doi: 10.1016/j.saa.2019.04.021. Epub 2019 Apr 18.

Authors

C Scirè¹, R G Urso², D Fulvio³, G A Baratta⁴, M E Palumbo⁴

Affiliations

¹ INAF - Osservatorio Astrofisico di Catania, via Santa Sofia 78, I-95123 Catania, Italy. Electronic address: carlotta.scire@inaf.it.
² INAF - Osservatorio Astrofisico di Catania, via Santa Sofia 78, I-95123 Catania, Italy; Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud, Université Paris-Saclay, batiment 121, Université Paris-Sud, 91405 Orsay Cedex, France.
³ Departamento de Fsica, Pontifcia Universidade Catolica do Rio de Janeiro, Rua Marqus de So Vicente 225, 22451-900, Rio de Janeiro, RJ, Brazil.
⁴ INAF - Osservatorio Astrofisico di Catania, via Santa Sofia 78, I-95123 Catania, Italy.

PMID: 31051423
DOI: 10.1016/j.saa.2019.04.021

Abstract

We present a novel experimental study on solid CH₂DOH pure and in astrophysical relevant mixtures. Solid samples were accreted under ultra high vacuum conditions at 17 K and were analyzed by mid-infrared transmission spectroscopy. Refractive index, density, and mid-IR band strength values were measured for pure solid CH₂DOH. The refractive index was also measured for CH₂DOH:H₂O, CH₂DOH:CO, and CH₂DOH:CH₃OH mixtures. For all samples, the thermal evolution of the main band profile was studied. We used the interference laser technique (HeNe laser, λ = 543.5 nm) to measure the samples thickness and a numerical method to measure the refractive index starting from the amplitude of the interference curve. We obtained the ice density through the Lorentz-Lorenz relation. To calculate the band strength values we used the linear fit of the integrated band intensities with respect to the column densities. Samples deposited at 17 K were warmed up to their sublimation temperature. Spectra were taken at selected temperatures to study their thermal evolution. The results are discussed in view of their relevance for the interpretation of astronomical IR spectra.

Keywords: Astrochemistry; Deuterated methanol; IR band strength; IR spectroscopy; ISM: molecules; Solid state.