title: EPR and optical absorption studies on VO2+ ions in L-asparagine monohydrate single crystals.
abstract: X-Band electron paramagnetic resonance (EPR) studies of VO(2+) ions in l-asparagine monohydrate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of two magnetically inequivalent VO(2+) sites. Both the vanadyl complexes are found to take up interstitial position. The angular variation of the EPR spectra in three planes ab, bc and ca are used to determine principal g and A tensors. For the two sites the spin Hamiltonian parameters are, site I: g(x)=1.9633, g(y)=2.0274, g(z)=1.9797, A(x)=88, A(y)=61, A(z)=161x10(-4)cm(-1); site II: g(x)=1.9627, g(y)=1.9880, g(z)=1.9425, A(x)=90, A(y)=66, A(z)=167x10(-4)cm(-1). The optical absorption study is also carried out at room temperature and absorption bands are assigned to various transitions. The theoretical band positions are obtained using energy expressions and a good agreement is found with the experimental values. By correlating EPR and optical data different molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed.
authors.affiliation: EPR Laboratory, Department of Physics, University of Allahabad, Allahabad 211002, India. ram_kripal2001@rediffmail.com
authors.forename: Ram
authors.initials: R
authors.lastname: Kripal
authors.forename: Indrajeet
authors.initials: I
authors.lastname: Mishra
authors.forename: S K
authors.initials: SK
authors.lastname: Gupta
authors.forename: Manju
authors.initials: M
authors.lastname: Arora
mesh_terms: D000042:Absorption; D001216:Asparagine / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003460:Crystallization; D004340:Drug Contamination; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D006860:Hydrogen Bonding; D006878:Hydroxides / Q000737:chemistry; D055620:Optical Phenomena; D017601:Oxygen Compounds / Q000737:chemistry*; D017968:Vanadium Compounds / Q000737:chemistry*
chemical_list: D002412:Cations; D006878:Hydroxides; D017601:Oxygen Compounds; D017968:Vanadium Compounds; D001216:Asparagine; C031356:hydroxide ion