Jump to main content
Jump to site search

Issue 36, 2018
Previous Article Next Article

The prediction of far-infrared spectra for planetary nitrile ices using periodic density functional theory with comparison to thin film experiments

Author affiliations

Abstract

Future spacecraft missions to planetary systems, Trans-Neptunian objects, and cometary bodies could implement far-infrared surveys to confirm the presence of condensed-phase species via their unique lattice features. For composite molecular ices of astrophysical significance, laboratory reference spectra are required to provide absorption coefficients used to quantify solid-state abundances. However, due to strong intermolecular interactions in polar ice systems, laboratory data of mixed-phase ices are difficult to interpret. In this study we have applied periodic density functional theory code to model bulk molecular crystals. This method allows for more accurate simulation of thin-film spectra than approaches simulating small clusters. For this proof-of-principle study on a series of pure nitrile ices of planetary interest, our simulated far-infrared spectra show excellent agreement to data from thin film studies performed at the Australian Synchrotron (crystalline acetonitrile and propionitrile) and to previously published spectra (hydrogen cyanide, acrylonitrile, cyanoacetylene, and cyanogen). The combined theoretical and experimental approach has provided a new explanation for the asymmetric profile of the hydrogen cyanide lattice feature and a more systematic assignment of nitrile ice absorption bands to low-frequency lattice modes. We nominate prominent absorption features for the detection of crystalline nitrile carriers located on planetary surfaces.

Graphical abstract: The prediction of far-infrared spectra for planetary nitrile ices using periodic density functional theory with comparison to thin film experiments

Back to tab navigation

Supplementary files

Publication details

The article was received on 04 Jul 2018, accepted on 30 Aug 2018 and first published on 07 Sep 2018


Article type: Paper
DOI: 10.1039/C8CP04219E
Citation: Phys. Chem. Chem. Phys., 2018,20, 23593-23605
  •   Request permissions

    The prediction of far-infrared spectra for planetary nitrile ices using periodic density functional theory with comparison to thin film experiments

    C. Ennis, R. Auchettl, D. R. T. Appadoo and E. G. Robertson, Phys. Chem. Chem. Phys., 2018, 20, 23593
    DOI: 10.1039/C8CP04219E

Search articles by author

Spotlight

Advertisements