Raman spectroscopy of new lead iodide intercalation compounds

PbI 2 crystals have been intercalated with ammonia, methylamine (CH 3 NH 2 ), ethylamine (C 2 H 5 NH 2 ), and butylamine (C 4 H 9 NH 2 ) for the first time. Raman spectra of these materials, and also of PbI 2 intercalated with nonylamine (C 9 H 19 NH 2 ) were obtained using an excitation wavelength of 514.531 nm. For comparison a study of the interaction of CdI 2 with the same molecules is included. Raman spectroscopy in the range 10-500 cm -1 demonstrated the occurrence of a polytypic phase transition from 1 T to 3 T on intercalation of PbI 2 and also that intercalation results in the breaking up of the crystal into many small crystallites. The existence of strong Pb-N interactions was demonstrated by both infrared and Raman spectroscopy.