THz spectroscopy of weakly bound cluster molecules in solid para-hydrogen: a sensitive probe of van der Waals interactions

Dmytro Mihrin, René Wugt Larsen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The present work demonstrates that 99.9% enriched solid para-H2 below 3 K provides an excellent inert and transparent medium for the exploration of large-amplitude intermolecular vibrational motion of weakly bound van der Waals cluster molecules in the THz spectral region. THz absorption spectra have been generated for CO2/H2O and CS2/H2O mixtures embedded in enriched solid para-H2 and numerous observed transitions associated with large-amplitude librational motion of the weakly bound binary CO2...H2O and CS2...H2O van der Waals cluster molecules have been assigned together with tentative assignments for the ternary CS2...(H2O)2 system. The interaction strength, directionality and anharmonicity of the weak van der Waals ‘‘bonds’’ between the molecules can be characterized via these THz spectral signatures and yield rigorous benchmarks for high-level ab initio methodologies. It is suggested that even a less stable linear conformation of the ternary CS2(H2O)2 system, where one H2O molecule is linked to each S atom of the CS2 subunit, may be formed due to the kinetics associated with the mobility of free H2O molecules in the soft para-H2 medium. In addition, the spectroscopic observations confirm a linear and planar global intermolecular potential energy minimum for the binary CS2...H2O system with C2v symmetry, where the O atom on the H2O molecule is linked to one of the S atoms on the CS2 subunit. A semi-experimental value for the vibrational zeropoint energy contribution of 1.93 ±  0.10 kJ mol-1 from the class of large-amplitude intermolecular vibrational modes is proposed. The combination with CCSD(T)/CBS electronic energy predictions provides a semi-experimental estimate of 5.08 0.15 kJ mol-1 for the binding energy D0 of the CS2...H2O van der Waals system.
Original languageEnglish
JournalPhysical Chemistry Chemical Physics
Volume21
Issue number1
Pages (from-to)349-358
Number of pages10
ISSN1463-9076
DOIs
Publication statusPublished - 2019

Cite this

@article{3deebabe64194ece98de6d1b8b6f79cf,
title = "THz spectroscopy of weakly bound cluster molecules in solid para-hydrogen: a sensitive probe of van der Waals interactions",
abstract = "The present work demonstrates that 99.9{\%} enriched solid para-H2 below 3 K provides an excellent inert and transparent medium for the exploration of large-amplitude intermolecular vibrational motion of weakly bound van der Waals cluster molecules in the THz spectral region. THz absorption spectra have been generated for CO2/H2O and CS2/H2O mixtures embedded in enriched solid para-H2 and numerous observed transitions associated with large-amplitude librational motion of the weakly bound binary CO2...H2O and CS2...H2O van der Waals cluster molecules have been assigned together with tentative assignments for the ternary CS2...(H2O)2 system. The interaction strength, directionality and anharmonicity of the weak van der Waals ‘‘bonds’’ between the molecules can be characterized via these THz spectral signatures and yield rigorous benchmarks for high-level ab initio methodologies. It is suggested that even a less stable linear conformation of the ternary CS2(H2O)2 system, where one H2O molecule is linked to each S atom of the CS2 subunit, may be formed due to the kinetics associated with the mobility of free H2O molecules in the soft para-H2 medium. In addition, the spectroscopic observations confirm a linear and planar global intermolecular potential energy minimum for the binary CS2...H2O system with C2v symmetry, where the O atom on the H2O molecule is linked to one of the S atoms on the CS2 subunit. A semi-experimental value for the vibrational zeropoint energy contribution of 1.93 ±  0.10 kJ mol-1 from the class of large-amplitude intermolecular vibrational modes is proposed. The combination with CCSD(T)/CBS electronic energy predictions provides a semi-experimental estimate of 5.08 0.15 kJ mol-1 for the binding energy D0 of the CS2...H2O van der Waals system.",
author = "Dmytro Mihrin and Larsen, {Ren{\'e} Wugt}",
year = "2019",
doi = "10.1039/c8cp05060k",
language = "English",
volume = "21",
pages = "349--358",
journal = "Physical Chemistry Chemical Physics",
issn = "1463-9076",
publisher = "Royal Society of Chemistry",
number = "1",

}

THz spectroscopy of weakly bound cluster molecules in solid para-hydrogen: a sensitive probe of van der Waals interactions. / Mihrin, Dmytro; Larsen, René Wugt.

In: Physical Chemistry Chemical Physics, Vol. 21, No. 1, 2019, p. 349-358.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - THz spectroscopy of weakly bound cluster molecules in solid para-hydrogen: a sensitive probe of van der Waals interactions

AU - Mihrin, Dmytro

AU - Larsen, René Wugt

PY - 2019

Y1 - 2019

N2 - The present work demonstrates that 99.9% enriched solid para-H2 below 3 K provides an excellent inert and transparent medium for the exploration of large-amplitude intermolecular vibrational motion of weakly bound van der Waals cluster molecules in the THz spectral region. THz absorption spectra have been generated for CO2/H2O and CS2/H2O mixtures embedded in enriched solid para-H2 and numerous observed transitions associated with large-amplitude librational motion of the weakly bound binary CO2...H2O and CS2...H2O van der Waals cluster molecules have been assigned together with tentative assignments for the ternary CS2...(H2O)2 system. The interaction strength, directionality and anharmonicity of the weak van der Waals ‘‘bonds’’ between the molecules can be characterized via these THz spectral signatures and yield rigorous benchmarks for high-level ab initio methodologies. It is suggested that even a less stable linear conformation of the ternary CS2(H2O)2 system, where one H2O molecule is linked to each S atom of the CS2 subunit, may be formed due to the kinetics associated with the mobility of free H2O molecules in the soft para-H2 medium. In addition, the spectroscopic observations confirm a linear and planar global intermolecular potential energy minimum for the binary CS2...H2O system with C2v symmetry, where the O atom on the H2O molecule is linked to one of the S atoms on the CS2 subunit. A semi-experimental value for the vibrational zeropoint energy contribution of 1.93 ±  0.10 kJ mol-1 from the class of large-amplitude intermolecular vibrational modes is proposed. The combination with CCSD(T)/CBS electronic energy predictions provides a semi-experimental estimate of 5.08 0.15 kJ mol-1 for the binding energy D0 of the CS2...H2O van der Waals system.

AB - The present work demonstrates that 99.9% enriched solid para-H2 below 3 K provides an excellent inert and transparent medium for the exploration of large-amplitude intermolecular vibrational motion of weakly bound van der Waals cluster molecules in the THz spectral region. THz absorption spectra have been generated for CO2/H2O and CS2/H2O mixtures embedded in enriched solid para-H2 and numerous observed transitions associated with large-amplitude librational motion of the weakly bound binary CO2...H2O and CS2...H2O van der Waals cluster molecules have been assigned together with tentative assignments for the ternary CS2...(H2O)2 system. The interaction strength, directionality and anharmonicity of the weak van der Waals ‘‘bonds’’ between the molecules can be characterized via these THz spectral signatures and yield rigorous benchmarks for high-level ab initio methodologies. It is suggested that even a less stable linear conformation of the ternary CS2(H2O)2 system, where one H2O molecule is linked to each S atom of the CS2 subunit, may be formed due to the kinetics associated with the mobility of free H2O molecules in the soft para-H2 medium. In addition, the spectroscopic observations confirm a linear and planar global intermolecular potential energy minimum for the binary CS2...H2O system with C2v symmetry, where the O atom on the H2O molecule is linked to one of the S atoms on the CS2 subunit. A semi-experimental value for the vibrational zeropoint energy contribution of 1.93 ±  0.10 kJ mol-1 from the class of large-amplitude intermolecular vibrational modes is proposed. The combination with CCSD(T)/CBS electronic energy predictions provides a semi-experimental estimate of 5.08 0.15 kJ mol-1 for the binding energy D0 of the CS2...H2O van der Waals system.

U2 - 10.1039/c8cp05060k

DO - 10.1039/c8cp05060k

M3 - Journal article

VL - 21

SP - 349

EP - 358

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 1

ER -