N. Mirchin et al., THEORETICAL APPROACH TO OPTICAL-RESPONSE PROPERTIES OF PHOTOPRECIPITATION IN IRRADIATED COLLOID SYSTEMS, Applied surface science, 106, 1996, pp. 418-421
Citations number
8
Categorie Soggetti
Physics, Condensed Matter","Chemistry Physical","Materials Science, Coatings & Films
In this work we describe some theoretical results of the photoexcitati
on process in colloidal systems in spatio-temporal terms of their opti
cal absorption constant alpha(x, t), Experimentally, in some colloidal
systems a photoprecipitation effect is observed which is enhanced aut
ocatalytically leading to an amplification effect. The amplification i
s understood here in the sense that new chromophores are created by a
positive feedback loop of photoprecipitation - photon absorption. This
causes an 'avalanche process' which makes the irradiated zone close t
o the window highly photoexcited but also obstructs the right penetrat
ion into the bulk of the photoreactor. From basic principles, we show
in a unidimensional spatial model that the amplification effect contai
ns a positive as well as a negative feedback term, which can be traced
to the physical phenomena occurring due to photoexcitation.