Semiconductor sensors in condensed media

Up to now we have considered the relationship between the concentration of active particles in systems like gas (vapour) - solid body (semiconductor) and variation of conductivity of a semiconductor. In connection to these systems we mentioned numerous relationships which may be used for quantitative assessment of the content of gaseous media on the basis of data provided by semiconductor sensors when analyzing various active components. 

Touching on drawbacks of vapour-liquid method, we should note that among those there is a lack of control of the thickness of condensed liquid layer on detector surface which may result (for fairly thick liquid layers) in diffusion retardation of oxygen chemisorbtion. The diffusion 

Apparently we can assume that chemical activity of surface oxygen complexes in relation to solvent considerably increases in highly polar media due to creation of contact or solvate-divided ion pairs 

Ion-radicals O2 generated on the surface interact fairly actively with molecules of various solvents. Peroxydes, hydroperoxydes, and other compounds may be produced as a result of such reaction. Due to low concentration of oxygen dissolved in the course of the experiment, small area of the film surface as well as low degree of occupation by charged molecules of chemisorbed oxygen (- 10 - 10 [55]) the accumulation rate of above products is low enough in this particular case. 

It is known that lifetime of solvated peroxyde ion-radicals vary in different solvents. Thus, it amounts to hours in pyridine and dimethyl-sulphoxide but falls far short of a minute in proton solvents like water or alcohols [56, 57]. 

---