Time-resolved infrared vibrational spectroscopy of the photoinduced phase transition of Pd(dmit)2 salts having different orders of phase transition

Naoto Fukazawa, Takahiro Tanaka, Tadahiko Ishikawa, Yoichi Okimoto, Shin Ya Koshihara, Takashi Yamamoto, Masafumi Tamura, Reizo Kato, Ken Onda

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21 Citations (Scopus)

Abstract

To clarify the mechanism of the later process of photoinduced phase transition (PIPT) in organic charge-transfer complexes, we examined by time-resolved infrared vibrational spectroscopy two dimeric anion radical salts, Et2Me2Sb[Pd(dmit)2]2 (Et 2Me2Sb salt) and Cs[Pd(dmit)2]2 (Cs salt) (Et, Me, and dmit are C2H5, CH3, and 1,3-dithiol-2-thione-4,5-dithiolate, respectively), having similar characteristics except for the order of their phase transitions at thermal equilibrium. The phase transition is first order for the Et2Me 2Sb salt and second order for the Cs salt at thermal equilibrium. Although both salts exhibit a high-temperature phase at later delay times (>100 ps) after the photoexcitation of the low-temperature phase, the time required for the emergence of the high-temperature phase was significantly different: 70 ps for the Et2Me2Sb salt and <0.1 ps for the Cs salt. The slow emergence of the high-temperature phase in the PIPT of the Et2Me2Sb salt presumably has an origin similar to that recognized for the first-order thermal phase transition, that is, steric effects of the Et2Me2Sb cation when the phase transitions occur.

Original languageEnglish
Pages (from-to)13187-13196
Number of pages10
JournalJournal of Physical Chemistry C
Volume117
Issue number25
DOIs
Publication statusPublished - Jun 27 2013
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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