VUV photochemistry and nuclear spin conversion of water and water–orthohydrogen complexes in parahydrogen crystals at 4 K
| Autor: | Amir Hossein Farahbod, Fatemeh S. Tahsildaran F, Hatsuki Otani, Brendan Moore, Takamasa Momose, Rasoul Malekfar, Termeh Bashiri, Pavle Djuricanin |
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| Rok vydání: | 2021 |
| Předmět: |
010304 chemical physics
Hydrogen Infrared Chemistry Radical Photodissociation General Physics and Astronomy chemistry.chemical_element 010402 general chemistry Spin isomers of hydrogen Photochemistry 01 natural sciences Spectral line 0104 chemical sciences 13. Climate action 0103 physical sciences Molecule Irradiation Physical and Theoretical Chemistry |
| Zdroj: | Physical Chemistry Chemical Physics. 23:4094-4106 |
| ISSN: | 1463-9084 1463-9076 |
| DOI: | 10.1039/d0cp04523c |
| Popis: | Samples of H2O, HDO, and D2O were isolated in solid parahydrogen (pH2) matrices and irradiated by vacuum ultraviolet (VUV) radiation at 147 nm. Fourier-Transform Infrared (FTIR) spectra showed a clear depletion of D2O and an enrichment of both HDO and H2O by 147 nm irradiation. These irradiation-dependent changes are attributed to the production of OH and/or OD radicals through photodissociations of H2O, HDO, and D2O. The radicals subsequently react with the hydrogen matrix, leading to the observed enrichment of H2O. No trace of isolated OH or OD was detected in the FTIR spectra, indicating that the OH/OD radicals react with the surrounding matrix hydrogen molecules via quantum tunneling within our experimental timescale. The observed temporal changes in concentrations, especially the increase of HDO concentration during VUV irradiation, can be interpreted by a model with a rapid conversion from orthohydrogen (oH2) to pH2 in water-oH2 complexes upon VUV photodissociation, indicating either the acceleration of the nuclear spin conversion (NSC) of H2 due to the magnetic moment of the intermediate OH/OD radical, or the preferential reaction of the OH/OD radical with a nearby oH2 molecule over other pH2 molecules. We have also identified and quantified an anomalously slow NSC of H2O and D2O complexed with oH2 in solid pH2. |
| Databáze: | OpenAIRE |
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