The reflectance spectra of single crystals of PbFCl and PbFBr are measured between 2.8 and 6.5 eV a t 84 and 295 K. The absorption spectra are calculated by Kramers-Kronig transformation. Peaks a t 4.55 and 5.13 eV in the absorption spectra of PbFBr and PbFCI, respect,ively, are attributed to cation exciton transitions. In the reflectance spectra of vacuum-cleaved single crystals of PbBr,, which are measured a t 84 K with different polarization directions, a new fine structure is observed. An interpretation is given based on an ionic model.
Es werden die Reflexionsspektren von PbFCl-und PbFBr-Einkristallen zwischen