dc.creator Dmitriev, Yu. A. en_US dc.date.accessioned 2007-11-20T17:06:54Z dc.date.available 2007-11-20T17:06:54Z dc.date.issued 1995 en_US dc.identifier 1995-MK-09 en_US dc.identifier.uri http://hdl.handle.net/1811/29547 dc.description Author Institution: A.F. Ioffe Physico-Technical Institute, St. Petersburg, 194021 Russia en_US dc.description.abstract Nitrogen atoms are trapped in solid $H_{2}$ and $D_{2}$ matrices from the gas discharge and studied by ESR. Two features are found. First, the ESR linewidth of N atoms in $H_{2}$ (0.8G) is smaller than in $D_{2} (1.2G)$, even though the nuclear magnetic moment $(\mu)^{H}$ is thrice as large as $\mu^{D}$, and the magnetic dipole interaction of the electron spin of a nitrogen atom with the nuclear magnetic moments of the surrounding matrix molecules should lead to a larger ESR linewidth for atoms trapped in $H_{2}$ than for atoms trapped in $D_{2}$. Second, the ESR lines of N in $H_{2}$ narrow with time after the sample sample condensation. These experimental results are explained by a stimulated ortho-para conversion of the molecules in the vicinity of the atomic nitrogen paramagnetic impurity. It is found that the value of the stimulated conversion rate for ortho-hydrogen molecules in the first coordination sphere with the center at the nitrogen atom lies in the limits $900 \pm 400 h^{-1}$, which is in agreement with the theoretical estimate of $610 h^{-1}$. The analysis carried out in the present work suggests that the observation of the ESR line broadening as the sample tempera ture increases for nitrogen atoms trapped in solid $H_{2}$ can be used as a method of investigation of thermally activated self-diffusion in that important low-temperature region (T < 10K) where the conventional method of measuring the relaxation time of NMR lines in solid $H_{2}$ loses its sensitivity. On the other hand, the predicted quantum-mechanical contributions to the diffusion of $H_{2}$ molecules, which are associated with a possible tunneling of molecules to a vacant site, can be observed just in the low-temperature region. en_US dc.format.extent 93228 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title ATOMIC NITROGEN IMPURITY IN SOLID $H_{2}$ AS A PROBE FOR STUDYING QUANTUM-MECHANICAL PROCESSES IN THE MATRIX en_US dc.type article en_US
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