Dynamics of Energy Transfer by Singlet Excitons in Naphthalene Crystals as Studied by Time-Resolved Spectroscopy

T h e t ime-resolved sensit ized fluorescence of anthracene-doped naphtha lene c rys ta l s fo l lowing picosecond-pulse exc i ta t ion w a s invest igated exper imenta l ly as a funct ion of d o p a n t concentrat ion a n d temperature . T h e influence of the exci tat ion intensity on the d e c a y of pure naphtha lene crys ta l s is s tudied a n d y ie lds an a lmost temperatureindependent annihi lat ion constant , y s s «a 4 x 1 0 ~ n c m 3 s _ 1 . T h e ana lys i s of the t ime-resolved host a n d guest fluorescence shows t h a t the energy t rans fe r rate , &HG> changes its funct ional f o r m with the guest concentrat ion. T h e temperature dependence of the energy t rans fer rate is expla ined t e n t a t i v e l y in te rms of phonon re laxat ion a n d phonon promot ion processes.