ELECTRON-ENERGY-LOSS SPECTROSCOPY OF SOLID PHENYLACETYLENE

A high-resolution electron-energy-loss spectrum of solid phenylacetyle ne has been recorded. The lowest singlet-triplet transition (1(1)A(1) --> 1(3)A(1)) shows more vibronic bands than previously observed. Semi -empirical calculations suggest that this transition relates to the L- 3(a) band of benzene, but the irregular vibronic structure hints towar ds a noticeable contribution from the side group. The second singlet-t riplet transition at 4.255 eV is also detected. According to the calcu lations it has two components (1(1)A(1) --> 1(3)B(2),2(3)A(1)) which c orrelate with the 3B(a,b) band in benzene. (C) 1998 Elsevier Science B .V.