Rovibrational transitions and nuclear spin conversion of methane in parahydrogen crystals
Solid parahydrogen is an excellent matrix for matrix-isolation spectroscopy because of its high spectral resolution. Here we describe the rovibrational structure and nuclear spin conversion of CH₄ embedded in parahydrogen crystals studied by infrared absorption spectroscopy. The vibration–rotation a...
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| Date: | 2000 |
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| Main Authors: | , |
| Format: | Article |
| Language: | English |
| Published: |
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2000
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| Series: | Физика низких температур |
| Subjects: | |
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| Journal Title: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Cite this: | Rovibrational transitions and nuclear spin conversion of methane in parahydrogen crystals / Masaaki Miki, Takamasa Momose // Физика низких температур. — 2000. — Т. 26, № 9-10. — С. 899-908. — Бібліогр.: 52 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| Summary: | Solid parahydrogen is an excellent matrix for matrix-isolation spectroscopy because of its high spectral resolution. Here we describe the rovibrational structure and nuclear spin conversion of CH₄ embedded in parahydrogen crystals studied by infrared absorption spectroscopy. The vibration–rotation absorptions of CH₄ exhibit time-dependent intensity changes at 4.8 K. These changes are interpreted to be a result of the I=1→I=2 nuclear spin conversion that accompanies the J=1→J=0 rotational relaxation. The half-lifetime of the upper J=1 rotational state is unchanged by the addition of up to 2% orthohydrogen molecules but decreases with more than 10% orthohydrogen molecules. The increase of the decay rate at higher orthohydrogen concentration indicates that the magnetic field gradient across CH₄ due to the orthohydrogen molecules mixes the nuclear spin states, which accelerates the conversion. |
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