Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique

Yu Fang Lee, Anne Marie Kelterer, Gergely Matisz, S. Kunsági-Máté, Chao Yu Chung, Yuan Pern Lee

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as MnW, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters MnW as protonated forms Mn−1WH+. The variations in intensities of Mn−1WH+ were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm−1. IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H2O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm−1, whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm−1. For M2W, the free OH band of H2O was observed at 3721 cm−1, whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm−1, corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M3W, the free OH shifted to 3715 cm−1, and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm−1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M4W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure, indicating significant contributions from branched isomers, which is distinctly different from M5 of which the cyclic form dominates.

Original languageEnglish
Article number144308
JournalJournal of Chemical Physics
Volume146
Issue number14
DOIs
Publication statusPublished - Apr 14 2017

Fingerprint

Infrared absorption
infrared absorption
Ionization
Methanol
depletion
methyl alcohol
Stretching
Infrared radiation
ionization
Water
water
Hydrogen
Hydrogen bonds
Photodissociation
Photoionization
Molecules
Infrared lasers
Mass spectrometers
infrared spectra
Isomers

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique. / Lee, Yu Fang; Kelterer, Anne Marie; Matisz, Gergely; Kunsági-Máté, S.; Chung, Chao Yu; Lee, Yuan Pern.

In: Journal of Chemical Physics, Vol. 146, No. 14, 144308, 14.04.2017.

Research output: Contribution to journalArticle

Lee, Yu Fang ; Kelterer, Anne Marie ; Matisz, Gergely ; Kunsági-Máté, S. ; Chung, Chao Yu ; Lee, Yuan Pern. / Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique. In: Journal of Chemical Physics. 2017 ; Vol. 146, No. 14.
@article{d8aabd58e67e4f889ceecc2982948878,
title = "Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique",
abstract = "We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as MnW, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters MnW as protonated forms Mn−1WH+. The variations in intensities of Mn−1WH+ were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm−1. IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H2O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm−1, whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm−1. For M2W, the free OH band of H2O was observed at 3721 cm−1, whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm−1, corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M3W, the free OH shifted to 3715 cm−1, and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm−1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M4W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure, indicating significant contributions from branched isomers, which is distinctly different from M5 of which the cyclic form dominates.",
author = "Lee, {Yu Fang} and Kelterer, {Anne Marie} and Gergely Matisz and S. Kuns{\'a}gi-M{\'a}t{\'e} and Chung, {Chao Yu} and Lee, {Yuan Pern}",
year = "2017",
month = "4",
day = "14",
doi = "10.1063/1.4979558",
language = "English",
volume = "146",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "14",

}

TY - JOUR

T1 - Infrared absorption of methanol-water clusters (CH3OH)n(H2O), n = 1-4, recorded with the VUV-ionization/IR-depletion technique

AU - Lee, Yu Fang

AU - Kelterer, Anne Marie

AU - Matisz, Gergely

AU - Kunsági-Máté, S.

AU - Chung, Chao Yu

AU - Lee, Yuan Pern

PY - 2017/4/14

Y1 - 2017/4/14

N2 - We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as MnW, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters MnW as protonated forms Mn−1WH+. The variations in intensities of Mn−1WH+ were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm−1. IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H2O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm−1, whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm−1. For M2W, the free OH band of H2O was observed at 3721 cm−1, whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm−1, corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M3W, the free OH shifted to 3715 cm−1, and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm−1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M4W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure, indicating significant contributions from branched isomers, which is distinctly different from M5 of which the cyclic form dominates.

AB - We recorded infrared (IR) spectra in the CH- and OH-stretching regions of size-selected clusters of methanol (M) with one water molecule (W), represented as MnW, n = 1-4, in a pulsed supersonic jet using the photoionization/IR-depletion technique. Vacuum ultraviolet emission at 118 nm served as the source of ionization in a time-of-flight mass spectrometer to detect clusters MnW as protonated forms Mn−1WH+. The variations in intensities of Mn−1WH+ were monitored as the wavelength of the IR laser light was tuned across the range 2700-3800 cm−1. IR spectra of size-selected clusters were obtained on processing of the observed action spectra of the related cluster-ions according to a mechanism that takes into account the production and loss of each cluster due to IR photodissociation. Spectra of methanol-water clusters in the OH region show significant variations as the number of methanol molecules increases, whereas those in the CH region are similar for all clusters. Scaled harmonic vibrational wavenumbers and relative IR intensities predicted with the M06-2X/aug-cc-pVTZ method for the methanol-water clusters are consistent with our experimental results. For dimers, absorption bands of a structure WM with H2O as a hydrogen-bond donor were observed at 3570, 3682, and 3722 cm−1, whereas weak bands of MW with methanol as a hydrogen-bond donor were observed at 3611 and 3753 cm−1. For M2W, the free OH band of H2O was observed at 3721 cm−1, whereas a broad feature was deconvoluted to three bands near 3425, 3472, and 3536 cm−1, corresponding to the three hydrogen-bonded OH-stretching modes in a cyclic structure. For M3W, the free OH shifted to 3715 cm−1, and the hydrogen-bonded OH-stretching bands became much broader, with a weak feature near 3179 cm−1 corresponding to the symmetric OH-stretching mode of a cyclic structure. For M4W, the observed spectrum agrees unsatisfactorily with predictions for the most stable cyclic structure, indicating significant contributions from branched isomers, which is distinctly different from M5 of which the cyclic form dominates.

UR - http://www.scopus.com/inward/record.url?scp=85017649483&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85017649483&partnerID=8YFLogxK

U2 - 10.1063/1.4979558

DO - 10.1063/1.4979558

M3 - Article

VL - 146

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 14

M1 - 144308

ER -