Surface-enhanced Raman scattering and SERRS imaging of phthalocyanine mixed films

The objective of the present work is the study of the surface-enhanced spec troscopy of mixed thin solid films of metallophthalocyanine (MPc; M=Cu, Co) and bis(n-propylimido)perylene (Bis-PTCDPr) materials fabricated by vacuum co-evaporation onto silver island films. The surface-enhanced Raman scatte ring (SERS) and surface-enhanced resonance Raman scattering (SERRS) of neat Bis-PTCDPr, CuPc and CoPc were also recorded using visible 514.5 and 633 n m laser lines and near-infrared excitation at 780 nm. During the investigat ion it was found that the Raman scattering (RS) and resonance Raman scatter ing (RRS) spectra of CuPc and CoPc films were sensitive to the irradiance a t the sample. To further explore the effect of local heating on the vibrati onal spectrum, a temperature dependence (between -180 and 200 degreesC) stu dy was carried out using the 514.5 nm laser Line with constant laser power. The overtones and combinations of the CuPc and CoPc molecules were also cl early observed in the RRS and SERRS spectra. The study of the SER(R)S spect ra allowed us to conclude that the dyes of the mixed films were physically adsorbed onto the silver islands. It is also shown that, in mixed films, di fferences in the absorption properties can be used to tune into the spectru m of any one of the components of the mixture with the appropriate laser li ne. For the first time, SERRS mapping and global imaging of mixed films obt ained with the 514.5 nm laser line are reported. Complementary information about the quality of the films, homogeneity and phase separation may be obt ained using SERRS imaging. Copyright (C) 2001 John Wiley & Sons, Ltd.