[01] Daisy Joseph, Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai, India.

Mn, Cr and Cu K X-ray absorption edges were measured in various compounds containing Mn in Mn²⁺, Mn³⁺ and Mn⁴⁺ oxidation states, Cr in Cr³⁺ and Cr⁶⁺ oxidation state and Cu in ²⁺ states in different compounds. Few compounds are having tetrahedral coordination in the 1^st shell surrounding the cation while others are having octahedral coordination. The measurements have been carried out at the energy dispersive EXAFS beamline at INDUS-2 Synchrotron radiation source at RRCAT, Indore. Energy shifts of ~ 8-16 eV were observed for Mn K edge in the Mn-compounds while a shift of 13-20 eV were observed for Cr K edge in Cr-compounds compared to their values in elemental Mn and Cr respectively. Cu showed an energy shift of 4-7 ev compared to the elemental Cu. The different chemical shifts observed for the compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on Mn, Cr and Cu cations in the above compounds.

INDUS, XAS, X-ray Absorption Edges, Oxidation State, Cation, Energy Shift

[01] M.N. Ghatikar, B.D. Padali, R.M. Nayak, J. Phys. C: Solid State Phys. 10 (1977) 4173. [02] A.R. Chetal, P. Mahto, P.R. Sarode, J. Phys. Chem. Sol. 49 (1988) 279. [03] V.K. Kondawar, C. Mande, J. Phys. C: Solid State Phys. 9 (1976) 1351. [04] C. Mande, M.Y. Apte, Bull. Mater. Sci. 3 (1981) 193. [05] A.K. Nigam, M.K. Gupta, J. Phys. F: Metal Phys. 4 (1974) 1084. [06] M.M. Ballal, C. Mande, J. Phys. Chem. Solids 38 (1977) 1383. [07] S.K. Pandey, A.R. Chetal, P.R. Sarode, J. Phys. Soc. Jpn. 59 (1990) 1848. [08] H.K. Hinge, S.K. Joshi, B.D. Shrivastava, J. Prasad, K. Srivastava, Ind. J. Pure Appl. Phys. 49 (2011) 168. [09] D. Bhattacharyya, A.K. Poswal, S.N. Jha, B. Sangeeta, S.C. Sabharwal, Nucl. Instrum. Meth. Phys. Res. A 609 (2009) 286. [10] D. Bhattacharyya, A.K. Poswal, S.N. Jha, B. Sangeeta, S.C. Sabharwal, Bull. Mater. Sci. 32 (2009) 103. [11] A. Gaur, B.D. Shrivastava, D.C. Gaur, J. Prasad, K. Srivastava, S.N. Jha, D. Bhattacharyya, A. Poswal, S.K. Deb, J. Co-ordin. Chem. 64 (2011) 1265. [12] A. Gaur, A. Johari, B D Shrivastava, D.C. Gaur, S.N. Jha, D. Bhattacharyya, A. Poswal, S.K. Deb, Sadhana 36 (2011) 339. [13] B.K. Agarwal, C.B. Bhargava, A.N. Vishnoi, V.P. Seth, J. Phys. Chem. Solids 37 (1976) 725. [14] M. Newville, B. Ravel, D. Haskel, J.J. Rehr, E.A. Stern, Y. Yacoby, Physica B 154 (1995) 208. [15] D. Joseph, A.K. Yadav, S.N. Jha and D. Bhattacharyya, Bullettin of Materials Science Vol 6, No.36, 2013 pp 1067-1072.