Münster 1997 – scientific programme
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CP: Chemische Physik
CP 9: Spektroskopie Moleküle (vormittags Ger, Nachmittags Gl)
CP 9.15: Talk
Thursday, March 20, 1997, 14:45–15:00, Gl
Electronic structure of α-sexithiophene: single crystals and UHV-grown films — •R.F. Mahrt2, R.N. Marks1, R. Michel1, M. Muccini1, M. Murgia1, R. Zamboni1, and C. Taliani1 — 1CNR, Inst. di Spettroscopia Molecolare Via P. Gobetti 101, Bologna, Italy — 2Fachbereich Physikalische Chemie und Zentrum f"ur Materialwissenschaften, Philipps-Universit"at Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
We report measurements on steady state and time resolved photoluminescence (PL) and PL-excitation (PLE) on sexithiophene films and single crystals. In contrast to the broad spectral features usually observed even in crystals, we have observed for the first time sharp emission peaks superimposed on a broad background. The lifetime of these sharp features is around 1 ns which is in good agreement with measurements on oligothiophenes in solution. The broad background is due to emission from defect states, which are observable in PLE measurements and site-selective PL. These defect states are visible in both films and crystals, but their density is strongly dependent on the growth conditions.