Femtosecond differential transmission spectroscopy of α-sexithienyl thin film

• Published in: Journal of luminescence Vol. 87; pp. 736 - 738
• Main Authors: Urbasch, G, Giessen, H, Murgia, M, Zamboni, R, Mahrt, R.F
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-05-2000; Elsevier
• Subjects: Applied sciences; Electrical, magnetic and optical properties; Exact sciences and technology; Oligothiophenes; Organic polymers; Physicochemistry of polymers; Properties and characterization; Ultrafast spectroscopy; Ultrafast spectroscopy; Oligothiophenes; Femtosecond; Conducting polymers; Differential spectrometry; Stark effect; Thiophene polymer; Experimental study; Oligomer; Low temperature; Thin film; Photoexcitation
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/S0022-2313(99)00380-4

We have investigated the nature of primary excitations in α-sexithienyl thin film by comparing excitations above and below the charge transfer exciton. We performed femtosecond differential transmission spectroscopy at low temperature. In the probed spectral region from 2 to 2.8 eV, we found a bleaching of the first excited singlet with a superimposed absorption into higher excited gerade states. During the first few picoseconds, the dynamics of the photoexcitations in the range of the first excited singlet manifold are independent of the excitation photon energy. When exciting below the origin of the first excited singlet, we observe an optical Stark effect. Thermal effects dominate the change in transmission for longer delay times for all excitation energies.