Absorption spectra of trapped electrons in nonpolar glasses: Oscillator strengths and threshold behaviors

Trapped electrons were generated by photoionization of TMPD (N,N,N',N'-tetr amethylparaphenylenediamine) and the absorption spectra measured in 2-methy lpentane (2MP), 3-methylpentane (3MP), cis-decalin (CD), methylcyclohexane (MCH), and deuterated methylcyclohexane(dh ICH) glasses at 77 K. The low en ergy absorption fits the Wigner 3/2 power law for threshold photodetachment , consistent with a ground S state with binding energy of 0.48 +/- 0.02 eV and a final continuum P state. For all solvents studied, the maximum absorp tion cross-section is located at ca. 0.7 eV with an extinction coefficient of 2.7 x 10(4) M-1 cm(-1) (determined by comparison to TMPD cation). From t he spectral distribution of the absorption (from 0.5 to 3.3 eV), experiment al oscillator strengths were determined to be 0.65(2MP), 0.63(3MP), and 0.7 6(CD). Various local field corrections to these experimental oscillator str engths are discussed.