In this work, it was found that exposure of TIN to ammonia (400 ppb-100 ppm
) in wet synthetic air at room temperature leads to a reversible decrease o
f Delta Phi. Then is a change of the work function of -30 meV/decade of inc
reasing ammonia concentration at room temperature. The response time (t(90)
) to 1 ppm is less than or equal to 1 min. The sensitivity is a typical roo
m temperature effect as it decreases at higher temperatures up to 100 degre
es C. The reaction has a low cross sensitivity to humidity, as - first - th
e sensitivity to ammonia does not depend on the relative humidity and - sec
ond - the work function change due to humidity changes is as low as -2 meV
for an increase of 10% in relative humidity. The Diffuse Reflectance Infrar
ed Fourier Transform Spectra (DRIFT-spectra) indicate that the adsorption o
f ammonia is correlated with a decrease of OH species on the surface. All d
ata are compared to the gas reactions of TiO2. (C) 2000 Elsevier Science S.
A. All rights reserved.