Spectroscopic Behaviour of Quasi-One-Dimensional Linear Chains in MgPt(CN)4 · 7 H2O Single Crystals

Abstract

In the direction of the crystallographic c-axis MgPt(CN)₄ · 7 H₂O has a relatively low Pt-Pt-distance (3.15 Å at 300°K). Thus the optical behaviour shows inter-molecular interactions. Single crystal polarized emission and absorption spectra were measured between 300°K and 5°K. In this temperature range the emission peaks shift to the red by about 1,100 cm^-1. This is attributed to a decrease in Pt-Pt-distance. MgPt(CN)₄ · 7 H₂O undergoes phase transitions at about 166°K and 60°K. To interprete the solid state emission and absorption behaviour the Davydov theory is applied. The two lowest excited bands of electronic origin are assigned to the symmetries Γ_2u(κ) and Γ_5u(κ) in the double group D′_8h·