title: Probing of local structures of thermal and photoinduced phases in rubidium manganese hexacyanoferrate by resonant Raman spectroscopy.
abstract: Resonant couplings of the electronic states and the stretching vibrations of CN(-) ligands, which bridges metal ions, is investigated by resonance Raman spectroscopy for Rb(0.94)Mn[Fe(CN)6](0.98)·0.2H2O. Large excitation wavelength dependences over one order of magnitude were found for Raman peaks corresponding to different valence pairs of metal ions in the excitation wavelength range between 350 and 632 nm. In the thermal low-temperature phase, the CN(-) stretching modes due to the low-temperature-phase configuration (Fe(2+)-Mn(3+)) and the phase-boundary configuration (Fe(3+)-Mn(3+)) are coupled to the Fe(2+)-to-Mn(3+) intervalence transfer band and Jahn-Teller distorted Mn(3+) d-d transition band, respectively. In the photoinduced low-temperature phase, the Fe(3+)-Mn(3+) mode shows strong resonant enhancement with the CN(-)-to-Fe(3+) charge-transfer band, which exists in the high-temperature phase with a cubic structure. From these resonance behaviors, we conclude that the local lattice symmetry of the photoinduced phase is cubic in contrast with the tetragonal symmetry in the thermal low-temperature phase.
authors.affiliation: Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Fukaya
authors.forename: Akifumi
authors.initials: A
authors.lastname: Asahara
authors.forename: Shun
authors.initials: S
authors.lastname: Ishige
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakajima
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tokoro
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Ohkoshi
authors.forename: Tohru
authors.initials: T
authors.lastname: Suemoto