The transmission coefficient for monoenergetic electrons (0.04 eV FWHM) passing through thin films (sim;100 Aring;) of molecular solids is measured as a function of electron energy in the range 0ndash;15 eV. The visibility of sharp maxima in the transmission spectra is enhanced by measuring the negative value of the second energy derivative of the transmitted current with respect to electron energy. In benzene, fluorobenzene, pyridine, benzaldehyde, furan, cyclohexene and 1,3hyphen; and 1,4hyphen;cyclohexadiene, the spectra exhibit from six to eight maxima, whereas in pyrrole and thiophene four structures are resolved. With the exception of the first two features in fluorobenzene and the first feature for the other solids investigated, all other maxima correlate within at least plusmn;0.5 eV with the gashyphen;phase electronic transitions. This correlation is achieved by increasing the energy scale of the transmission spectra relative to the gashyphen;phase electronic energy levels. These findings corroborate previous experiments on solid organic films by Hamill and cohyphen;workers who attributed peaks in the first energy derivative of the transmitted current to energyhyphen;loss events. It is shown that the transmission features can arise either from an increase in the overall transmission coefficient due to the production of inelastically scattered electrons or from the formation of an electronndash;exciton complex through the temporary capture of an injected excess electron by field of a Frenkel exciton. The first lowhyphen;energy feature in each spectrum may possibly arise from an enhancement of vibrational excitation related to the energy dependence of the structure factor.
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