The nature of trapped electrons

First of all let us dwell upon the mechanism of electron trapping during radiolysis of vitreous matrices. The general form of this mechanism can be represented by the scheme 

An electron torn away from a molecule, M, of a matrix (or an additive) by a y-quantum, by a secondary electron, or by a light quantum [reaction (1)1 is thermalized, i.e. slowed down to the rate of thermal motion [process (2)] and is then captured by a trap T [reaction (3)]. For the electron to be stabilized in the trap the energy level in this trap should be lower than the botton of the matrix conduction band (Fig. 1). The experimental investigations carried 

It is assumed that, in both models of electron stabilization in water-alkaline matrices, there are small cavities in which the neighbouring water molecules are directed to each other with atoms of the same nature (with hydrogen atoms) while energetically the contact of atoms of different nature (i.e. H and O capable of forming a hydrogen bond) would be more favorable. For concentrated solutions of electrolytes, however, one should expect a considerable fraction of the water molecules to enter solvation shells of anions and cations. Under these conditions it seems quite probable that traps of the type depicted in Fig. 2(b) are formed in the contact sites of the solvation shells of two or several cations. This suggestion is supported by the 

Other matrices containing sufficient amounts of water (aqueous solutions of salts and alcohols) can also be expected to have trap structures of the types presented in Fig. 2. 

For vitrified MTHF the electron echo data correspond to the model of interaction of the trapped electron with the protons of three molecules of MTHF (Fig. 3), the distance from the electron to all the ring protons of MTHF molecules being the same (3.4 A) and the protons of the methyl group of MTHF molecules being located at far greater distances from the electron [10,11]. 

---