Magnetic field-induced changes in the electronic absorption intensities of NENB

Abstract Ni[C 2 H 8 N 2 ] 2 NO 2 BF 4 (NENB) is isostructural to Ni[C 2 H 8 N 2 ] 2 NO 2 ClO 4 , a prototypical Haldane compound. We report the polarized optical transmittance of NENB as a function of applied magnetic field ( H ) up to 30 T. Electronic absorption intensities become modified above the critical field ( H c ≈7.5–10.5 T, as determined from weak kinks in the magnetization data). For H > H c , the intensities of Ni 2+ d – d excitations in both polarizations are diminished, whereas the charge transfer transition along the nickel chain is enhanced.