TY - JOUR

T1 - Effect of Temperature on the OH-Stretching Bands of the Methanol Dimer

AU - Vogt, Emil

AU - Jensen, Casper Vindahl

AU - Kjaergaard, Henrik G.

N1 - Funding Information: We are grateful for funding from the Independent Research Fund Denmark (grant no. 9040-00142B) and the Novo Nordisk Foundation (grant nos. NNF19OC0057374 and NNF220C0080193) and for computer time from the High Performance Computer Centre at University of Copenhagen. Publisher Copyright: © 2024 American Chemical Society.

PY - 2023

Y1 - 2023

N2 - We present a conceptually simple model for understanding the significant spectral changes that occur with the temperature in the infrared spectra of hydrogen-bound complexes. We have measured room-temperature spectra of the methanol dimer and two deuterated isotopologues in the OH(D)-stretching region. We correctly predict spectral changes observed in the gas phase for the bound OH stretch in the methanol dimer from jet-cooled to room temperature and corroborate this with experimental and theoretical results for deuterated isotopologues. The origin of the observed spectral features is explained based on a reduced-dimensional vibrational model, which includes the two high-frequency OH stretches, the two methyl torsions, and the six intermolecular low-frequency vibrations. Key to the success of the model is a new coordinate definition to describe the intrinsic large-amplitude curvilinear motion of low-frequency vibrations. Despite the deceivingly simple appearance of the room temperature bound OH-stretching fundamental band, it consists of ∼107 vibrational transitions.

AB - We present a conceptually simple model for understanding the significant spectral changes that occur with the temperature in the infrared spectra of hydrogen-bound complexes. We have measured room-temperature spectra of the methanol dimer and two deuterated isotopologues in the OH(D)-stretching region. We correctly predict spectral changes observed in the gas phase for the bound OH stretch in the methanol dimer from jet-cooled to room temperature and corroborate this with experimental and theoretical results for deuterated isotopologues. The origin of the observed spectral features is explained based on a reduced-dimensional vibrational model, which includes the two high-frequency OH stretches, the two methyl torsions, and the six intermolecular low-frequency vibrations. Key to the success of the model is a new coordinate definition to describe the intrinsic large-amplitude curvilinear motion of low-frequency vibrations. Despite the deceivingly simple appearance of the room temperature bound OH-stretching fundamental band, it consists of ∼107 vibrational transitions.

U2 - 10.1021/acs.jpca.3c06456

DO - 10.1021/acs.jpca.3c06456

M3 - Journal article

C2 - 38179925

AN - SCOPUS:85182004649

VL - 128

SP - 392

EP - 400

JO - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory

JF - Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory

SN - 1089-5639

IS - 2

ER -