Grazing angle photoluminescence of porous alumina as an analytical transducer for gaseous ethanol detection

Abstract

Porous alumina was used to build an optical sensor for gaseous ethanol detection. The photoluminescence collected in a grazing angle was used as a transducer signal. The photoluminescence detected with this optical setup shows well resolved Fabry-Pérot type interference fringes at room temperature, whose position and shape are strongly dependent on the ethanol fraction adsorbed on the porous alumina surface. According to the surface porous morphology, different finesse and resolution between the emission fringes were observed. The analytical response of the sensor was tested in terms of spectral displacement of the fringes when in contact with gaseous ethanol. The sensor was tested for different temperatures and at 25 °C it presented the highest sensibility. The difference in the sensibility is a function of the temperature and can be related both to the modification of ethanol vapor pressure and the kinetics of adsorption processes at the walls of the glass cell and the porous alumina sample.