Spectroscopic investigation of the dynamical behavior of the photoinduced phase transition ofNa0.6Co1.3[Fe(CN)6

Abstract

The dynamics of the photoinduced phase transition ͑PIPT͒ has been investigated for the Co-Fe cyanides film, Na 0.6 Co 1.3 ͓Fe͑CN͒ 6 ͔ •4H 2 O, by means of the transient absorption spectroscopy. At low temperatures ͑Շ150 K͒, the compound shows the permanent PIPT from the low-spin phase ͓LS phase: LS Co 3+ ͑t 2g↑ 3 t 2g↓ 3 ͒-LS Fe 2+ ͑t 2g↑ 3 t 2g↓ 3 ͔͒ to the high-spin phase ͓HS phase; HS Co 2+ ͑t 2g↑ 3 t 2g↓ 2 e g↑ 2 ͒-LS Fe 3+ ͑t 2g↑ 3 t 2g↓ 2 ͔͒. We have found that the film shows the transient PIPT into the HS phase above ϳ170 K, and the lifetime PI of the photoinduced phase exponentially decreased from 10 ms at 170 K to ϳ100 s at 260 K. In the early stage ͑⌬t ഛ 200 ns͒ of the PIPT, we further have observed a characteristic photoinduced absorption band ͑Y band͒ and ascribed the band to the LS Co 2+ ͑t 2g↑ 3 t 2g↓ 3 e g↑ 1 ͒ state.

Electronic phase diagram of valence-controlled cyanide:Na0.84−δCo[Fe(CN)Nakada1, Kamioka2, Moritomo3 et al. 2008Phys. Rev. BSelf Cite410440View full textAdd to dashboardCite

“…Among them, the lowest-lying band ͑CT band͒ is ascribed the electron transfer from the Co 2+ site to the Fe 3+ site. 10,14,15 We decomposed the absorption spectra ␣͑͒ into the four absorption bands,…”

“…The solution reaction procedure, however, alters not only 1 − y but also the Na concentration ͑x͒ and water content ͑z͒. In addition, the obtained powders are not suitable for the optical measurement, especially for the time-resolved spectroscopy, [14][15][16] due to the intense light scattering. These situations may discourage the quantitative argument on the experimental data.…”

Charge-Transfer Dynamics in Cyano-BridgedMA–Fe System (MA=Mn, Fe, and Co)

“…4.93H 2 O 6) ) and Mn-Fe compound (e.g., RbMn[Fe(CN) 6 ] 7) ) show characteristic photoinduced magnetism at low temperatures, due to the photoinduced macroscopic charge-transfer (CT) and resultant structural phase transition (CT phase transition). 8,9) Thus far, we have performed nanosecond time-resolved spectroscopy on a Co-Fe cyanide film 18,19) and revealed that the photoinduced phase transition occurs via a hidden phase 20) with high-spin Co 3þ (t 4 2g e 2 g ) species. A systematic investigation with changes in the combination and composition of the elements will give us a more comprehensive insight on the photoinduced effect on the transition metal cyanides.…”

Role of the intermediate state in the photoinduced process ofCo−Fecyanide

“…The irreversibility of the PIPT, however, prevents the detailed investigation on the dynamics of the PIPT. Recently, Yamauchi et al 16 overcame the difficulty and reported a dynamics of the PIPT in the Co-Fe cyanide: their idea is that the relaxation time ͑ PI ͒ of the photoinduced metastable state becomes faster at high temperature, which enable us to perform a time-resolved experiment.…”