%0 Journal Article
%A Yachmenev, Andrey
%A Yang, Guang
%A Zak, Emil
%A Yurchenko, Sergei
%A Küpper, Jochen
%T The nuclear-spin-forbidden rovibrational transitions of water from first principles
%J The journal of chemical physics
%V 156
%N 20
%@ 0021-9606
%C Melville, NY
%I American Institute of Physics
%M PUBDB-2022-01426
%P 204307
%D 2022
%X The water molecule occurs in two nuclear-spin isomers that differ by the value of the total   nuclear spin of the hydrogen atoms, i.e., I=0 for para-H<sub>2</sub>O and I=1 for   ortho-H<sub>2</sub>O. Spectroscopic transitions between rovibrational states of ortho and   para water are extremely weak due to the tiny hyperfine nuclear-spin-rotation interaction   of only  ∼ 30 kHz and so far were not observed. We report the first comprehensive   theoretical investigation of the hyperfine effects and ortho-para transitions in   H<sub>2</sub><sup>16</sup>O due to nuclear-spin-rotation and spin-spin interactions. We also present the   details of our newly developed general variational approach to the simulation of hyperfine   effects in polyatomic molecules. Our results for water suggest that the strongest ortho-para   transitions with room-temperature intensities on the order of   10<sup>−31</sup> cm/molecule are about an order of magnitude larger than previously predicted values   and should be detectable in the mid-infrared ν<sub>2</sub> and near-infrared   2ν<sub>1</sub>+ν<sub>2</sub> and ν<sub>1</sub>+ν<sub>2</sub>+ν<sub>3</sub> bands by current spectroscopy experiments.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:35649881
%U <Go to ISI:>//WOS:000802881400011
%R 10.1063/5.0090771
%U https://bib-pubdb1.desy.de/record/475684