FIZIKA A 4 (1995) 3, 637-646

FINE PHENOMENA IN THE EPR SPECTRA OF THE HOLE-LIKE PARAMAGNETIC CENTRE IN CYTOSINE HYDROCHLORIDE

DUBRAVKA KRILOV^a, KREŠIMIR SANKOVIĆ^c, TATJANA PRANJIĆ-PETROVIĆ^b and JANKO N. HERAK^c
aSchool of Medicine and ^cFaculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia
^bSchool of Medicine, University of Rijeka, Rijeka, Croatia

Dedicated to Professor Mladen Paić on the occasion of his 90^th birthday

Received 24 July 1995

The fine phenomena in the EPR spectra of the hole-like paramagnetic centre formed in cytosine(thiocytosine)-HCl crystals upon irradiation are studied with EPR spectroscopy. The spin Hamiltonian including the electronic Zeeman term, hyperfine coupling, quadrupole coupling and the nuclear Zeeman term has been used in the second-order perturbation treatment for the interpretation of the experimental observations. It is shown that the quadrupolar term causes a detectable shift of the EPR lines and also induces the "forbidden'' transitions. From the shift of the "allowed'' transitions and the positions of the ``forbidden'' transitions, the chlorine quadrupolar coupling tensor [P], has been determined.

UDC 538.955
PACS 76.30.-v

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