Knowledge of the diffusion of chemicals through buried films
is important for a wide variety of systems—from sensing to drug delivery. Herein, we show that second-harmonic generation(SHG) can be used to follow the diffusion through a thin film buried under a liquid in situ. More specifically, the diffusion of 4-(4-diethylaminostyryl)-1-methylpyridinium iodide through zeolite precursor films of different thickness is followed.
The diffusion coefficients are calculated according to