Accession Number : AD0695630

Title :   ELECTRON DE-TRAPPING PROCESSES IN ANTHRACENE INVOLVING TRIPLET AND SINGLET EXCITONS.

Descriptive Note : Final technical rept. Sep 68-Aug 69,

Corporate Author : HEBREW UNIV JERUSALEM (ISRAEL)

Personal Author(s) : Many,A. ; Teucher,I. ; Yanovsky,R.

Report Date : AUG 1969

Pagination or Media Count : 32

Abstract : The work reported here is a continuation of the dark- and photo-current measurements in anthracene. Results are given and detailed arguments are presented in support of our earlier conclusion that for samples provided with alkali-metal contacts the photocurrent in the photon-energy range 0.9 - 3.3 eV originates entirely from optical excitation of electrons out of traps. The traps are filled by injection from the alkali-metal contact. Improved spectral resolution in the measurement of the spectral response of the photocurrent yield has enabled a more detailed characterization of the electronic-vibronic energy level structure. The long-wavelength data indicate that the structure of the lower portion of the anthracene conduction band reflects the interaction of one or more narrow electronic bands with vibronic modes of energies 0.03 - 0.08 eV. At shorter wavelengths (hv = 1.7 - 2.7 eV), where de-trapping occurs primarily by photo-generated triple excitons, many vibronic splittings of the triplet state could be clearly resolved. A theoretical analysis of the kinetics of the de-trapping process is presented. A preliminary comparison between experimental curves of the photocurrent bleaching decay and the predictions of the analysis yield for de-trapping probabilities for interaction of an occupied trap with triplet and singlet electrons are given. (Author)

Descriptors :   (*ANTHRACENES, *EXCITONS), (*PHOTOELECTRIC EFFECT, ANTHRACENES), SINGLE CRYSTALS, ALKALI METALS, PHOTONS, MOLECULAR ENERGY LEVELS, PHOTOCONDUCTIVITY, ISRAEL

Subject Categories : Radiation and Nuclear Chemistry
      Electricity and Magnetism
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE