Sub-doppler infrared spectroscopy of jet cooled NDH3+: N–H stretch vibrations in a key astrochemical ion

Scrape, Preston G.

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https://hdl.handle.net/2142/100502 Copy

Description

Title

Sub-doppler infrared spectroscopy of jet cooled NDH3+: N–H stretch vibrations in a key astrochemical ion

Author(s)

Scrape, Preston G.

Contributor(s)

• Nesbitt, David
• Lesko, Daniel
• Kortyna, Andrew

Issue Date

2018-06-20

Keyword(s)

Astronomy

Abstract

The ammonium-d cation (NDH+ 3 ) is the singly-deuterated isotologue of ammonium (NH+ 4 ), an abundant species in terrestrial chemistry that has been proposed as a key species in the chemistry of interstellar objects. Unlike NH+ 4 , NDH+ 3 has a nonzero rotational dipole transition moment, so it can be detected by its microwave emissions. To assist in the detection of this ion, we have collected rovibrationally resolved infrared spectra of its symmetric (ν1, A1) and asymmetric (ν4, E) N–H stretching modes, with special attention to accurately determining its ground-state rotational constants. In this study, NDH+ 3 is generated by seeding NDH2 in a H2/Ne/He mixture through a pulsed slit discharge. Electron ionization of H2 in the mixture produces H+, which readily protonates other H2 molecules to form H+ 3 ; this H+ 3 goes on to protonate NDH2. The resulting NDH+ 3 ions are cooled in a slit jet supersonic expansion to a rotational temperature of 40 K. Rotational constants for the ground state and both singly-excited vibrational states, as well as the ν1 and ν4 band origins, are obtained by least-squares fitting of the sub-Doppler rotational structure to a symmetric top Hamiltonian. The fitted band origins agree with the best theoretical predictions to within 1 cm−1 .

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100502

DOI

10.15278/isms.2018.WL06

Copyright and License Information

Copyright 2018 Preston G. Scrape

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