XANES SPECTROSCOPIC STUDIES OF MEROCYANINE DYES AND THEIR ADSORBED STATES ON AGCL

We studied the sulfur K-edge XANES spectra of several merocyanine dyes and an antifoggant PMTZ (phenylmercaptotetrazole) in the form of neat powder and adsorbed state on AgCl. Reflecting the localized nature of core excitations, the spectra of merocyanine dyes can be interpreted as contributions from S atoms in three chemical environments. The spectra of these dyes adsorbed on AgCl show significant change when S atom is in the thione (=S) form, while little change was observed when S is in the thia (-S-) form in the aromatic ring. This indicates that the dye in the thione form is adsorbed at the C=S group, while the dye with thia form may be adsorbed at other site than S. The deposition of PMTZ on AgCl also caused significant spectral change, which corresponds to the strong interaction of PMTZ with AgCl at the S site.