Influence of surface microstructure on optical response of ruthenium-porphyrins thin films gas sensor

This paper reports an attempt to improve the response of a metalloporphyrin Langmuir-Blodgett films, n-tetraphenyl porphine ruthenium (II) carbonyl, towards several vapor samples by means of surface microstructure modi. cation. Four different surface microstructures were prepared by annealing the thin films samples in air at three different temperatures; 50, 100 and 150 degreesC, for one hour. Three types of vapor samples with different physico-chemical properties, namely saturated vapor of methanol, ethanol and 2-propanol in 15 l/min of air flow, were used. The sensing sensitivity was based on the change in the optical absorption of the film upon exposure towards the gas samples that was measured at a particular wavelength, i.e., 514 nm, of the light source. It was observed that the response of the thin films was influenced by its surface microstructure, which the smoother the surface the higher the response is. The correlation between the microstructure of the films surface and its gas sensing property will be discussed.