The weak fundamental NH-stretching transition in amines

Sidsel Dahl Schrøder; Anne Schou Hansen; Jens Heide Wallberg; Anne Rath Nielsen; Lin Du; Henrik Grum Kjærgaard

doi:10.1016/j.saa.2016.09.003

The weak fundamental NH-stretching transition in amines

Sidsel Dahl Schrøder, Anne Schou Hansen, Jens Heide Wallberg, Anne Rath Nielsen, Lin Du, Henrik Grum Kjærgaard

Department of Chemistry

7 Citations (Scopus)

Abstract

Absolute intensities of NH-stretching fundamental and overtone transitions of gas phase aniline, methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine have been measured with long path length conventional absorption spectroscopy. To support the assignments of NH-stretching transitions, transition frequencies and intensities were calculated with the local mode model using ab initio calculated local mode parameters and dipole moment functions obtained at the CCSD(T)-F12a/VDZ-F12 level of theory. For aniline, the absolute intensities of the NH-stretching transitions show the typical decrease of approximately an order of magnitude for each successive vibrational excitation. For methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine, the observed absolute intensities of the fundamental NH-stretching transition is weak and of similar strength or even weaker than the corresponding first overtone transition. Characteristic for the amines with a normal fundamental intensity is a conjugated double bond next to the amine group.

Original language	English
Journal	Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Volume	173
Pages (from-to)	201-206
Number of pages	6
ISSN	1386-1425
DOIs	https://doi.org/10.1016/j.saa.2016.09.003
Publication status	Published - 15 Feb 2017

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title = "The weak fundamental NH-stretching transition in amines",

abstract = "Absolute intensities of NH-stretching fundamental and overtone transitions of gas phase aniline, methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine have been measured with long path length conventional absorption spectroscopy. To support the assignments of NH-stretching transitions, transition frequencies and intensities were calculated with the local mode model using ab initio calculated local mode parameters and dipole moment functions obtained at the CCSD(T)-F12a/VDZ-F12 level of theory. For aniline, the absolute intensities of the NH-stretching transitions show the typical decrease of approximately an order of magnitude for each successive vibrational excitation. For methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine, the observed absolute intensities of the fundamental NH-stretching transition is weak and of similar strength or even weaker than the corresponding first overtone transition. Characteristic for the amines with a normal fundamental intensity is a conjugated double bond next to the amine group.",

author = "Schr{\o}der, {Sidsel Dahl} and Hansen, {Anne Schou} and Wallberg, {Jens Heide} and Nielsen, {Anne Rath} and Lin Du and Kj{\ae}rgaard, {Henrik Grum}",

year = "2017",

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day = "15",

doi = "10.1016/j.saa.2016.09.003",

language = "English",

volume = "173",

pages = "201--206",

journal = "Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy",

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TY - JOUR

T1 - The weak fundamental NH-stretching transition in amines

AU - Schrøder, Sidsel Dahl

AU - Hansen, Anne Schou

AU - Wallberg, Jens Heide

AU - Nielsen, Anne Rath

AU - Du, Lin

AU - Kjærgaard, Henrik Grum

PY - 2017/2/15

Y1 - 2017/2/15

N2 - Absolute intensities of NH-stretching fundamental and overtone transitions of gas phase aniline, methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine have been measured with long path length conventional absorption spectroscopy. To support the assignments of NH-stretching transitions, transition frequencies and intensities were calculated with the local mode model using ab initio calculated local mode parameters and dipole moment functions obtained at the CCSD(T)-F12a/VDZ-F12 level of theory. For aniline, the absolute intensities of the NH-stretching transitions show the typical decrease of approximately an order of magnitude for each successive vibrational excitation. For methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine, the observed absolute intensities of the fundamental NH-stretching transition is weak and of similar strength or even weaker than the corresponding first overtone transition. Characteristic for the amines with a normal fundamental intensity is a conjugated double bond next to the amine group.

AB - Absolute intensities of NH-stretching fundamental and overtone transitions of gas phase aniline, methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine have been measured with long path length conventional absorption spectroscopy. To support the assignments of NH-stretching transitions, transition frequencies and intensities were calculated with the local mode model using ab initio calculated local mode parameters and dipole moment functions obtained at the CCSD(T)-F12a/VDZ-F12 level of theory. For aniline, the absolute intensities of the NH-stretching transitions show the typical decrease of approximately an order of magnitude for each successive vibrational excitation. For methylamine, ethylamine, cyclopropylamine, methylethylamine, diethylamine and pyrrolidine, the observed absolute intensities of the fundamental NH-stretching transition is weak and of similar strength or even weaker than the corresponding first overtone transition. Characteristic for the amines with a normal fundamental intensity is a conjugated double bond next to the amine group.

U2 - 10.1016/j.saa.2016.09.003

DO - 10.1016/j.saa.2016.09.003

M3 - Journal article

C2 - 27664544

SN - 1386-1425

VL - 173

SP - 201

EP - 206

JO - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

JF - Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

ER -

The weak fundamental NH-stretching transition in amines

Abstract

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