scholarly journals Equilibrium Structure in the Presence of Methyl Internal Rotation: Microwave Spectroscopy and Quantum Chemistry Study of the Two Conformers of 2-Acetylfuran

2021 ◽  
Author(s):  
Christina Dindić ◽  
Arne Lüchow ◽  
Natalja Vogt ◽  
Jean Demaison ◽  
Ha Vinh Lam Nguyen
Keyword(s):  
Quantum Chemistry ◽  
Internal Rotation ◽  
Equilibrium Structure ◽  
Microwave Spectroscopy

Xe···OCS: Relatively Straightforward?

2020 ◽  
Author(s):  
Peter Kraus ◽  
Daniel A. Obenchain ◽  
Sven Herbers ◽  
Dennis Wachsmuth ◽  
Irmgard Frank ◽  
...  
Keyword(s):  
Relativistic Effects ◽  
Equilibrium Structure ◽  
Microwave Spectroscopy ◽  
Mass Dependent

<div>The Xe···OCS complex is studied using microwave spectroscopy. Nine isotopologues are measured, and a mass-dependent rm(2) structure is presented. The experiments are supported with a wide array of calculations, including CCSD(T), SAPT, as well as double-hybrid DFT. Trends in the structures of six Rg···OCS complexes (He, Ne, Ar, Kr, Xe, and Hg) are investigated, with particular attention to the deformation of the OCS monomer and relativistic effects. The experimental near-equilibrium structure of Xe···OCS can be predicted to within 11 milliangstrom in the Xe···C distance by correlated wavefunction theory.<br></div>

Xe···OCS: Relatively Straightforward?

2020 ◽  
Author(s):  
Peter Kraus ◽  
Daniel A. Obenchain ◽  
Sven Herbers ◽  
Dennis Wachsmuth ◽  
Irmgard Frank ◽  
...  
Keyword(s):  
Relativistic Effects ◽  
Equilibrium Structure ◽  
Microwave Spectroscopy ◽  
Mass Dependent

<div>The Xe···OCS complex is studied using microwave spectroscopy. Nine isotopologues are measured, and a mass-dependent rm(2) structure is presented. The experiments are supported with a wide array of calculations, including CCSD(T), SAPT, as well as double-hybrid DFT. Trends in the structures of six Rg···OCS complexes (He, Ne, Ar, Kr, Xe, and Hg) are investigated, with particular attention to the deformation of the OCS monomer and relativistic effects. The experimental near-equilibrium structure of Xe···OCS can be predicted to within 11 milliangstrom in the Xe···C distance by correlated wavefunction theory.<br></div>

scholarly journals Understanding (coupled) large amplitude motions: the interplay of microwave spectroscopy, spectral modeling, and quantum chemistry

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ha Vinh Lam Nguyen ◽  
Isabelle Kleiner
Keyword(s):  
Fourier Transform ◽  
Quantum Chemistry ◽  
Large Amplitude ◽  
Environmental Chemistry ◽  
Broad Band ◽  
Microwave Spectroscopy ◽  
Rotational Spectrum ◽  
Spectral Modeling ◽  
Rotational Spectra ◽  
Large Amplitude Motions

AbstractA large variety of molecules contain large amplitude motions (LAMs), inter alia internal rotation and inversion tunneling, resulting in tunneling splittings in their rotational spectrum. We will present the modern strategy to study LAMs using a combination of molecular jet Fourier transform microwave spectroscopy, spectral modeling, and quantum chemical calculations to characterize such systems by the analysis of their rotational spectra. This interplay is particularly successful in decoding complex spectra revealing LAMs and providing reference data for fundamental physics, astrochemistry, atmospheric/environmental chemistry and analytics, or fundamental researches in physical chemistry. Addressing experimental key aspects, a brief presentation on the two most popular types of state-of-the-art Fourier transform microwave spectrometer technology, i.e., pulsed supersonic jet expansion–based spectrometers employing narrow-band pulse or broad-band chirp excitation, will be given first. Secondly, the use of quantum chemistry as a supporting tool for rotational spectroscopy will be discussed with emphasis on conformational analysis. Several computer codes for fitting rotational spectra exhibiting fine structure arising from LAMs are discussed with their advantages and drawbacks. Furthermore, a number of examples will provide an overview on the wealth of information that can be drawn from the rotational spectra, leading to new insights into the molecular structure and dynamics. The focus will be on the interpretation of potential barriers and how LAMs can act as sensors within molecules to help us understand the molecular behavior in the laboratory and nature.

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