Optical absorption spectra of small particles of K+TCNQ– and related compounds

Abstract

The optical absorption spectra of small particles of K⁺TCNQ^–, Na⁺TCNQ^–, Li⁺TCNQ^–, Rb⁺TCNQ^– and Cs⁺TCNQ^–(where TCNQ is 7,7,8,8-tetracyanoquinodimethane) surrounded by CCl₄, KBr and other dielectrics have been studied. The low frequency band, in each salt, is shifted to lower frequencies but the high frequency bands remain unshifted as the size of particles or the dielectric constant of the surrounding medium increases. The low frequency spectra are in qualitative agreement with those calculated by equations of Mie–Gans and Fuchs. The spectra of small particles of the compounds above are similar to infrared spectra of small particles of diatomic polar crystals (i.e., NaCl or ZnS).