Using Chiroptical Spectroscopy to Gain Unique Information about the Solid‐State

The solid-state can provide unique and rich science as molecules which are under the strong influence of neighboring molecules behave differently from those in solution. For chiral systems, chiroptical spectroscopy, CD (circular dichroism), and CPL (circular polarized luminescence) provide information at the molecular level; however, they encounter serious problems of contamination by signals arising from intrinsic macroscopic anisotropies, i.e. LD (linear dichroism) and LB (linear birefringence). This chapter describes the methods to obtain true chiroptical spectra in the solid-state. Measurement of randomly oriented samples by transmittance as in a KBr/KCl pellet or in a nujol mull, or by diffuse reflectance are successful. Specially designed instruments for CD such as UCS (universal chiroptical spectrometer)-1, 2, and 3, HAUP (high accuracy universal polarimeter), and MC (multichannel)-CD are described. For CPL, purpose-built CPL-200 and D-CCS (dual-polarization modulated comprehensive chiroptical spectrophotometer) are described. Representative applications for inorganic and organic as well as biological samples are shown.