Electronic absorption and MCD spectra for Pt(AuPPh3)(8)(2+) and Au(AuPPh3)(8)(3+) cluster complexes in poly(methyl methacrylate) thin films at 295 and 10 K

Electronic absorption and 8 T magnetic circular dichroism (MCD) spectra are reported for nitrate salts of Pt(AuPPh3)(8)(2+) and AU(AUPPh(3))(8)(3+) in poly(methyl methacrylate) (PMM) thin films at 295 and 10 K in the vis-UV r egion from 1.6 to 3.6 mu m(-1) (1 mu m(-1) = 10(4) cm(-1)). Enhanced resolu tion is observed at low temperature, especially for Pt(AuPPh3)(8)(2+), whic h emphasizes the differences in the nature of the low-energy excited config urations and states between Pt(AuPPh3)(8)(2+) and Au(AuPPh3)(8)(3+). The ab sorption and MCD spectra for Pt(AuPPh3)s2+ are interpreted in terms of a co mbination of excitations from filled Pt 5d orbitals to empty Au framework 6 s orbitals and intraframework Au-8(2+) (IF) transitions, whereas the spectr a for Au(AuPPh3)(8)(3+) are ascribed entirely to Au IF transitions.