Characterization techniques vibronic

The first two terms describe, respectively, the radical electrons and the molecular vibrations in the absence of vibronic coupling. Linear electron-molecular vibration (e-mv) coupling is described explicitly by the third term in Eq. (2). The set of G constants gj denotes linear monomer TT-electron - molecular vibration coupling constants. In the following sections, the indicatrix measurements, electronic and molecular spectroscopies, and other techniques are analyzed as methods of characterizing the organic conductors. 

The simplest aromatic molecule, benzene, is characterized by a lowest absorption band that is located relatively far in the ultraviolet (37,800 cm ) and is dipole forbidden ( B2 in Dg/,). The same applies to the second absorption band ( Bi at 46,500 cm ). The lowest-energy allowed transition ( Ei ) is located at about 52,700 cmAll these transitions are well outside the range where their resonance Raman spectra can be studied in detail by present-day techniques. However, some preresonance data are available (Ziegler and Albrecht, 1977 Ohta and Ito, 1977b Ito et al., 1978), which allow a partial analysis of vibronic coupling channels in benzene. 

---