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Q: Quantenoptik

Q 35: Laser Spectroscopy

Q 35.6: Talk

Friday, April 6, 2001, 17:00–17:15, H 2013

Excited State Absorption (ESA) in functionalized nano layers measured by diffraction at a laser induced transient population grating — •David von Seggern, Christian Spitz, Axel Heuer, and Ralf Menzel — Universität Potsdam, Physik, Am Neuen Palais 10, 14469 Potsdam

In ESA-spectroscopy (ESA=Excited State Absorption) the sample to be investigated is excited by laser light of high intensity. A sufficient amount of chromophores has to be pumped into the excited state to stand out against the ground state absorption when probed by a second light pulse. This method is unfavourable for samples being destroyed by these high excitation intensities. Moreover, the optical density of the sample has to be relatively high.

These problems can be avoided by transient grating- (TG-) spectroscopy: two laser beams of not necessarily high intensities are being crossed inside the sample. Inside the overlapping region the properties of the sample are being modulated periodically and probe light can be diffracted at the resulting grating-like structure. Only wavelengths in the region of the excited state absorption are diffracted without any background of the ground state absorption.

In this talk we will present ESA-experiments realized by TG-spectroscopy. The experiments were carried out in order to prepare investigations on charge-transfer-reactions in nanostructured functional layers.

(Funded by the DFG, SFB 448/TP A2)