Sub-doppler Jet-cooled Infrared Spectroscopy Of Nd2h2+ And Nd3h+ In The Nh Stretch Fundamental Modes

Chang, Chih-Hsuan

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https://hdl.handle.net/2142/50826 Copy

Description

Title

Sub-doppler Jet-cooled Infrared Spectroscopy Of Nd2h2+ And Nd3h+ In The Nh Stretch Fundamental Modes

Author(s)

Chang, Chih-Hsuan

Contributor(s)

Nesbitt, David

Issue Date

2014-06-16

Keyword(s)

Astronomy

Abstract

Sub-Doppler jet-cooled rovibrational spectra of ND$_{3}$H$^{+}$, ND$_{2}$H$_{2}$$^{+}$, and NDH$_{3}$$^{+}$ ions in various fundamental NH modes were observed and analyzed using difference frequency generation infrared spectroscopy. The ions were generated in the concentration-modulation slit-jet expansion via a H$_{3}$$^{+}$ proton transfer mechanism in a discharge mixture of ND$_{3}$/H$_{2}$O and H$_{2}$ gases. NH mode excitation in ND$_{3}$H$^{+}$ ion yielded a prominent \textit{Q} branch feature and parallel band rotational structure. Rotational transitions were confirmed unambiguously by four-line ground state combination differences within frequency measurement accuracy (10 MHz). The band origin was determined to be 3316.8413(9) cm$^{-1}$. Perturbation in the upper state was observed from analysis of residuals. In the case of ND$_{2}$H$_{2}$$^{+}$, both NH symmetric (\textit{b}-type) and anti-symmetric (\textit{c}-type) modes were observed and assigned for the first time, yielding band origins of 3297.5440(1) and 3337.9050(1) cm$^{-1}$, respectively. The intensity for the two fundamental bands was interpreted with simple context of a bond-dipole model. The present study provided high precision ground state rotational constants (\textit{A}$^{''}$=4.85675(4), \textit{B}$^{''}$=3.96829(4), \textit{C}$^{''}$=3.44667(6) cm$^{-1}$), which should facilitate microwave searches for isotope-substituted ammonium ions in the regions of interstellar medium, such as dense molecular clouds or younger stellar objects.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/50826

DOI

https://doi.org/10.15278/isms.2014.WF04

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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