University of Illinois Urbana-Champaign

Photochemical generation of H2NCNX, H2NNCX, H2NC(NX) (X = O, S) in low-temperature matrices

Voros, Tamas

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873093.pptx

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https://hdl.handle.net/2142/96795

Description

Title
Photochemical generation of H2NCNX, H2NNCX, H2NC(NX) (X = O, S) in low-temperature matrices
Author(s)
Voros, Tamas
Contributor(s)
  • Tarczay, Gyorgy
  • Magyarfalvi, Gabor
  • Lajgut, Gyozo Gyorgy
Issue Date
2017-06-21
Keyword(s)
Astronomy
Date of Ingest
  • 2017-07-27T20:14:50Z
  • 2018-01-29T23:02:30Z
Abstract
The [NH$_{2}$, C, N, O] and the [NH$_{2}$, C, N, S] systems were investigated by quantum-chemical computations and matrix-isolation spectroscopic methods. The equilibrium structures of the isomers and their relative energies were determined by CCSD(T) method. This was followed by the computation of the harmonic and anharmonic vibrational wavenumbers, infrared intensities, relative Raman activities and UV excitation energies. These computed data were used to assist the identification of products obtained by UV laser photolysis of 3,4-diaminofurazan, 3,4-diaminothiadiazole and 1,2,4-thiadiazole-3,5-diamine in low-temperature Ar and Kr matrices.footnote{T. Voros, Gy. Gy. Lajgut, G. Magyarfalvi, Gy. Tarczay, J. Chem. Phys., 146, 024305, 2017.}_x000d_ Experimentally, first the precursors were studied by matrix-isolation IR and UV spectroscopic methods. Based on these UV spectra, different wavelengths were selected for photolysis. The irradiations, carried out by a tunable UV laser-light source, resulted in the decomposition of the precursors, and in the appearance of new bands in the IR spectra. Some of these bands were assigned to cyanamide (H$_{2}$NCN) and its isomer, the carbodiimide molecule (HNCNH), generated from H$_{2}$NCN. By the analysis of the relative absorbance vs. photolysis time curves, the other bands were grouped to three different species both for the O- and the S-containing systems. In the case of the O-containing isomers, these bands were assigned to the H$_{2}$NNCO:H$_{2}$NCN, and H$_{2}$NCNO:H$_{2}$NCN complexes, and to the ring-structure H$_{2}$NC(NO) isomer. In a similar way, the complexes of H$_{2}$NNCS and H$_{2}$NCNS with the H$_{2}$NCN, and H$_{2}$NC(NS) were also identified. 1,2,4-thiadiazole-3,5-diamine was also investigated in similar way like the above mentioned precursors. The results of this study also support the identification of the new S-containing isomers. Except for H$_{2}$NNCO and H$_{2}$NCNS, these molecules were not identified previously. It is expected that at least some of these species, like the methyl isocyanate (CH$_{3}$CNO) isomerfootnote{D. T. Halfen, V. V. Ilyushin, L. M. Ziurys, Astrophys. J., 812, L5, 2015.}$^{,}$footnote{J. Cernicharo et. al., Astron. Astrophys., 587, L4, 2016.}, are present and could be identified in astrophysical objects._x000d_ _x000d_ _x000d_ _x000d_ _x000d_
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Permalink
http://hdl.handle.net/2142/96795
DOI
https://doi.org/10.15278/isms.2017.WA10
Copyright and License Information
Copyright 2017 Tamas Voros

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Abstracts & Presentations - 2017 International Symposium on Molecular Spectroscopy PRIMARY