Infrared spectra of protonated quinoline (1-C9H7NH+) in solid para-hydrogen

Tseng, Chih-Yu

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https://hdl.handle.net/2142/96806 Copy

Description

Title

Infrared spectra of protonated quinoline (1-C9H7NH+) in solid para-hydrogen

Author(s)

Tseng, Chih-Yu

Contributor(s)

Lee, Yuan-Pern

Issue Date

2017-06-21

Keyword(s)

Astronomy

Abstract

Large protonated polycyclic aromatic hydrocarbons (H$^{+}$PAH) and polycyclic aromatic nitrogen heterocycles (H$^{+}$PANH) have been proposed as possible carriers of unidentified infrared (UIR) emission bands from galactic objects. The nitrogen atom in H$^{+}$PANH is expected to induce a blue shift of the C=C stretching band near 6.2 $mu$m so that their emission bands might agree with the UIR band better than those of H$^{+}$PAH._x000d_ _x000d_ In this work, we report the IR spectrum of protonated quinoline and its neutral species measured upon electron bombardment during deposition of a mixture of quinoline and textsl{para}-hydrogen at 3.2 K. New features were assigned to 1-chem{C_9H_7NH}$^{+}$ and 1-chem{C_9H_7NH}, indicating that the protonation and hydrogenation occur at the N-atom site. The intensities of features of 1-chem{C_9H_7NH}$^{+}$ diminished when the matrix was maintained in darkness for 10 h, whereas those of 1-chem{C_9H_7NH} increased. Spectral assignments were made according to comparison of experimental results with anharmonic vibrational wavenumbers and IR intensities calculated with the B3LYP/6-311++G(d,p) method. Although agreement between the observed spectrum of 1-chem{C_9H_7NH}$^{+}$ and the UIR emission bands is unsatisfactory, presumably because of the small size of quinoline, we did observe C=C stretching bands at 1641.4, 1598.4, 1562.0 wn, blue-shifted from those at 1618.7, 1580.8, 1510.0 wn of the corresponding protonated PAH (C$_{10}$H$_{9}$$^{+}$), pointing to the direction of the UIR bands._x000d_

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/96806

DOI

https://doi.org/10.15278/isms.2017.WA12

Copyright and License Information

Copyright 2017 Chih-Yu Tseng

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