IR Studies of the Spin–Nuclear Conversion in the Vicinity of \(\alpha \)-\(\beta \)- Transition in Cryodeposited Methane Films
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Solid methane belongs to a group of crystals containing hydrogen atoms, whose macroscopic properties are greatly influenced by the spin interaction of hydrogen nuclei. In particular, the methane molecule, which has four protons with spin I=1/2, has three total spin modifications: para-, ortho- and meta-states with three values of the total spin moments of 0, 1 and 2, respectively. Equilibrium concentrations of these modifications and relaxation times are dependent on the temperature, affecting the observed thermal properties of solid methane, such as thermal conductivity, specific heat, thermal expansion. In this paper, we attempt to explain the peculiarities of thin film growth of methane at cryogenic temperatures from the viewpoint of spin–nuclear transformations. Our observations of absorption intensity at a frequency corresponding to 1/2 of the absorption band amplitude of deformation vibrations record a step-like change in the position of the absorption band during the sample deposition process. The observed phenomenon, in our opinion, is the demonstration of spin transformations during deposition.
KeywordsMethane Spin Cryodeposit IR spectroscopy
The work was financially supported by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan within the Program of the Special-purpose financing of fundamental research.
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