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# FORBIDDEN ROTATION TRANSITIONS BETWEEN NUCLEAR SPIN MODIFICATIONS IN POLYATOMIC MOLECULES BY NUCLEAR SPIN-ROTATION INTERACTIONS

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/17345

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 dc.creator Chan, Man-Chor en_US dc.creator Sarka, K. en_US dc.creator Oka, T. en_US dc.date.accessioned 2006-06-15T18:03:49Z dc.date.available 2006-06-15T18:03:49Z dc.date.issued 1987 en_US dc.identifier 1987-TF-1 en_US dc.identifier.uri http://hdl.handle.net/1811/17345 dc.description $^{1}$ Wigner, E.P. Z. Phys. Chem. B 1933, 23, 28 $^{2}$ Van Vleck, J.H. Revs. Mod. Phys. 1951, 23, 213 $^{3}$ Curl, Jr., R.F., Kasper, J.V.V., and Pitzer, K.S. J. Chem. Phys 1967, 46, 3220 en_US dc.description Author Institution: Department of Chemistry and Department of Astronomy and Astrophysics, The University of Chicago; Department of Physics, India Institute of Technology en_US dc.description.abstract The nuclear spin-rotation interaction Hamiltonian of polyatomic molecules with different symmetries has been derived with respect to the molecule-fixed axes. Terms diagonal in the basis set | IJFMF) cause nuclear hyperfine structure whereas the off-diagonal ones give rise to the conversion between different nuclear spin states. The basic difference between them is the symmetry upon permuting the spin coordinates of identical nuclei. Based on Wigner's idea on the stability of ortho- and para- hydrogen,1 a group theoretical method is developed to discriminate the diagonal terms from the off-diagonal ones. We use an extended group in which pure nuclear permutation operations are added to the usual molecular symmetry group. The diagonal terms are totally symmetric to these added operations while the non-diagonal terms are not. Van Vleck's reverse angular momentum method2 has been applied to evaluate the off-diagonal matrix elements. We estimate the order of magnitude of the conversion rate3 due to this interaction and discuss some experimental observations. en_US dc.format.extent 194565 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.title FORBIDDEN ROTATION TRANSITIONS BETWEEN NUCLEAR SPIN MODIFICATIONS IN POLYATOMIC MOLECULES BY NUCLEAR SPIN-ROTATION INTERACTIONS en_US dc.type article en_US