F. Nishida et al., IN-SITU FLUORESCENCE PROBING OF THE CHEMICAL-CHANGES DURING SOL-GEL THIN-FILM FORMATION, Journal of the American Ceramic Society, 78(6), 1995, pp. 1640-1648
Pyranine (8-hydroxy-1,3,6-trisulfonated pyrene) was used as an in situ
fluorescence probe to monitor the chemical evolution during sol-gel t
hin film deposition of silica by the dip-coating process. The sensitiv
ity of pyranine luminescence to protonation/deprotonation effects mas
used to quantify changes in the mater/alcohol ratio in real time as th
e substrate was withdrawn from the sol reservoir. The spatially resolv
ed spectral results showed that preferential evaporation of alcohol oc
curred, and that the solvent composition in the vicinity of the drying
line reached values in excess of 80 vol% water Correlation of the lum
inescence results with the interference pattern of the depositing film
allowed the solvent composition to be mapped as a function of film th
ickness.