Optical observations of new halogen-bridged platinum complexes assembled within a ladder lattice

Abstract

New varieties of quasi-one-dimensional transition metal (M)-halide (X) compounds, $$(\hbox{C}_8\hbox{H}_6\hbox{N}_4)[\hbox{Pt}(\hbox{C}_2\hbox{H}_8\hbox{N}_2)\hbox{Cl}]_2\hbox{Cl}(\hbox{ClO}_4)_3\cdot \hbox{H}_2\hbox{O}$$ and $$(\hbox{C}_{10}\hbox{H}_8\hbox{N}_2)[\hbox{Pt}(\hbox{C}_4\hbox{H}_{13}\hbox{N}_3)\hbox{Br}]_2\hbox{Br}_4\cdot 2\hbox{H}_2\hbox{O},$$ comprising two-leg ladders of mixed-valent platinum complexes, are theoretically investigated with particular emphasis on their photoresponses. Observations of the polarized optical conductivity prove the interchain valence arrangement to be in phase in the former but out of phase in the latter. Possible nonlinear lattice relaxation originating with a photogenerated exciton is also simulated in an attempt to further elucidate the contrast between them.