Soft-x-ray fluorescence study of the quasi-one-dimensional Heisenberg antiferromagnet tetraphenylverdazyl

Abstract

Soft-x-ray fluorescence measurements have been performed on a single crystal of the organic antiferromagnet 2,4,6-triphenylverdazyl. Resonant and nonresonant C K alpha and N K alpha (2p-->1s transition) x-ray emission spectra (XES) were measured and compared with x-ray photoelectron valence band spectra and deMon density-functional theory calculations. It is shown that intramolecular interactions are much stronger than intermolecular ones and give the main contribution to the formation of C 2p density of states. We present evidence of a delocalization of unpaired N 2p electrons over the verdazyl ring. The excitation energy dependence of C K alpha and N K alpha XES observed below the C Is and N Is thresholds, respectively, is discussed in terms of symmetry selective resonant inelastic x-ray scattering.