International Conference on METALS IN SOLUTION
J. Phys. IV France 01 (1991) C5-283-C5-290
LUMINESCENCE STUDIES OF CRYSTALLINE SODIDESG. XU1, Ta.-R. PARK1, R.S. BANNWART1, A. SIERADZAN2, M.G. DEBACKER3, S.A. SOLIN4 and J.L. DYE5
1 Departments of Chemistry and Physics/Astronomy and the Center for Fundamental Materials Research, Michigan State University, East Lansing, Michigan 48824, U.S.A.
2 Department of Physics, Central Michigan University, Mount Pleasant, Michigan, 48859, U.S.A.
3 Laboratoire de Chimie Physique (associé au CNRS URA 253), HEI, 13 rue de Toul, F-59046 Lille cedex, France
4 NEC Research Institute, 4 Independence Way, Princeton, NJ 08540, U.S.A.
5 To whom correspondance should be addressed
The sodium anion, Na-, both in solution and in crystalline sodides, has a broad intense absorption band at 1.7 - 1.9 eV, which is assigned to the [MATH] optical transition. In single crystals of Na+(cryptand[2.2.2])Na-, a narrow emission band (fwhm = 0.03 eV) occurs from a highly mobile excited state (exciton-polariton). The peak position is time-dependent, shifting from 1.86 eV to 1.835 eV over a 30 ns time span. The emission intensities, peak shapes and time-profiles have now been measured for a number of salts of Na-. The photophysical properties of alkalides are complicated and very dependent on the synthesis method and purity of the compound. Defect electrons appear to be effective fluorescence quenchers and most sodides show much lower emission intensities than the nearly defect-free "parent" alkalide, Na+(C222)Na-. A model for light absorption and emission by crystalline sodides is discussed and related to the experimental results.
© EDP Sciences 1991