Photoemission Study of Temperature-Induced and Photoinduced Spin-State Transitions in Spin-Crossover Complex [Fe(ptz)₆](BF₄)₂

Abstract

We report an x-ray photoemission spectroscopy study of spin-crossover complex [Fe(ptz)₆](BF₄)₂ (ptz = 1-propyltetrazole) to identify the electronic changes due to temperature-induced and photoinduced spin transitions. The energy difference between the Fe 2p and F 1s peaks is found to correlate with the low-spin (LS) to high-spin (HS) transition of [Fe(ptz)₆](BF₄)₂. The Fe 2p_3⁄2 spectrum of the HS state is accompanied by a charge-transfer satellite and is analyzed by configuration-interaction cluster-model calculations. Based on the electronic-structure parameters from the cluster-model analysis, the stability of the LS state against the HS state is calculated as a function of the Fe–N bond length. A drastic bond-length reduction is required to stabilize the LS state and is also related to the observed core-level shift. The postillumination spectral shape well reproduces the spectrum before the laser illumination, suggesting that the surface of the Fe complex is chemically stable against the laser illumination for the photoinduced spin transition.