CHARACTERIZATION OF PHOTOPYROELECTRIC VAPOR ANALYSIS

In this work we present the quantitative and qualitative detection of organic vapours by a photopyroelectric (PPE) sensor. The PPE sensor co nsists of a pyroelectric detector covered with a sensitive polymer fil m. The vapour is sorbed within the him and excited by infrared radiati on. The heat obtained by thermal relaxation depends on the amount of s orbed vapour. Finally, the electrical output of the pyroelectric detec tor is a function of the vapour concentration. The use of monochromati c light guarantees high selectivity. This is shown for a PPE sensor, c overed with polyvinylpyrrolidone, detecting a mixture of water and met hanol vapour. Furthermore, PPE spectroscopy is used to find suitable i nfrared wavelengths for improving the detector sensitivity. The PPE si gnal as a function of methanol vapour concentration and methanol mass loading within the sensitive polyvinylpyrrolidone film shows that the best sensitivities are given at low concentrations. The partition coef ficient characterizing the quantity of sorption of the polymer film in dicates that a polyvinylpyrrolidone-covered sensor exhibits a higher s ensitivity for methanol than for dichloromethane.