How to determine the pressure of a methane-containing gas mixture by means of two weak Raman bands, v(3) and 2v(2)

Susanne Brunsgaard Hansen, Rolf W. Berg, Erling Halfdan Stenby

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Raman spectra of a pure CH4 sample, two CH4-C2H6 mixtures and a CH4-N2 mixture were obtained as a function of pressure at pressures up to 39.6 MPaA (MPa absolute). These spectra are presented in the region 3120-2980 cm-1. A clear pressure dependence of the area ratio between two weak methane bands, n3 (asymmetric C-H stretching) and 2n2 (overtone of the asymmetric C-H bending), is observed; the methane n3 band intensity is lowered relative to the methane 2n2 as the pressure is raised. The intensity ratios between these two bands, In3/I2n2, were determined and plotted as a function of pressure. Surprisingly it is observed that the ratio at a fixed pressure is independent of the composition and thereby of the surroundings in which the methane molecule is vibrating. A model function to predict the pressure is given. From a practical point of view, the present results could be useful for determining directly the total pressure in methane mixtures the composition of which is not known.
Original languageEnglish
JournalJournal of Raman Spectroscopy
Volume33
Issue number3
Pages (from-to)160-164
Publication statusPublished - 2002

Cite this

@article{9f918a7fb2a247bca856794ec3caee15,
title = "How to determine the pressure of a methane-containing gas mixture by means of two weak Raman bands, v(3) and 2v(2)",
abstract = "Raman spectra of a pure CH4 sample, two CH4-C2H6 mixtures and a CH4-N2 mixture were obtained as a function of pressure at pressures up to 39.6 MPaA (MPa absolute). These spectra are presented in the region 3120-2980 cm-1. A clear pressure dependence of the area ratio between two weak methane bands, n3 (asymmetric C-H stretching) and 2n2 (overtone of the asymmetric C-H bending), is observed; the methane n3 band intensity is lowered relative to the methane 2n2 as the pressure is raised. The intensity ratios between these two bands, In3/I2n2, were determined and plotted as a function of pressure. Surprisingly it is observed that the ratio at a fixed pressure is independent of the composition and thereby of the surroundings in which the methane molecule is vibrating. A model function to predict the pressure is given. From a practical point of view, the present results could be useful for determining directly the total pressure in methane mixtures the composition of which is not known.",
author = "Hansen, {Susanne Brunsgaard} and Berg, {Rolf W.} and Stenby, {Erling Halfdan}",
year = "2002",
language = "English",
volume = "33",
pages = "160--164",
journal = "Journal of Raman Spectroscopy",
issn = "0377-0486",
publisher = "JohnWiley & Sons Ltd.",
number = "3",

}

How to determine the pressure of a methane-containing gas mixture by means of two weak Raman bands, v(3) and 2v(2). / Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan.

In: Journal of Raman Spectroscopy, Vol. 33, No. 3, 2002, p. 160-164.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - How to determine the pressure of a methane-containing gas mixture by means of two weak Raman bands, v(3) and 2v(2)

AU - Hansen, Susanne Brunsgaard

AU - Berg, Rolf W.

AU - Stenby, Erling Halfdan

PY - 2002

Y1 - 2002

N2 - Raman spectra of a pure CH4 sample, two CH4-C2H6 mixtures and a CH4-N2 mixture were obtained as a function of pressure at pressures up to 39.6 MPaA (MPa absolute). These spectra are presented in the region 3120-2980 cm-1. A clear pressure dependence of the area ratio between two weak methane bands, n3 (asymmetric C-H stretching) and 2n2 (overtone of the asymmetric C-H bending), is observed; the methane n3 band intensity is lowered relative to the methane 2n2 as the pressure is raised. The intensity ratios between these two bands, In3/I2n2, were determined and plotted as a function of pressure. Surprisingly it is observed that the ratio at a fixed pressure is independent of the composition and thereby of the surroundings in which the methane molecule is vibrating. A model function to predict the pressure is given. From a practical point of view, the present results could be useful for determining directly the total pressure in methane mixtures the composition of which is not known.

AB - Raman spectra of a pure CH4 sample, two CH4-C2H6 mixtures and a CH4-N2 mixture were obtained as a function of pressure at pressures up to 39.6 MPaA (MPa absolute). These spectra are presented in the region 3120-2980 cm-1. A clear pressure dependence of the area ratio between two weak methane bands, n3 (asymmetric C-H stretching) and 2n2 (overtone of the asymmetric C-H bending), is observed; the methane n3 band intensity is lowered relative to the methane 2n2 as the pressure is raised. The intensity ratios between these two bands, In3/I2n2, were determined and plotted as a function of pressure. Surprisingly it is observed that the ratio at a fixed pressure is independent of the composition and thereby of the surroundings in which the methane molecule is vibrating. A model function to predict the pressure is given. From a practical point of view, the present results could be useful for determining directly the total pressure in methane mixtures the composition of which is not known.

M3 - Journal article

VL - 33

SP - 160

EP - 164

JO - Journal of Raman Spectroscopy

JF - Journal of Raman Spectroscopy

SN - 0377-0486

IS - 3

ER -