We have developed Raman gain spectroscopy with femtosecond resolution. The advantage of the method is as follows: (1) There is no disturbance from fluorescence as in spontaneous Raman scattering; (2) The interference of the signal with nonresonant background does not appear. This is extremely advantageous to time-resolved CARS spectroscopy. We have applied this new method to excitons in polydiacetylene (PDA), polythiophenes, and a polyacetylene derivative with only 1.5 ps lifetime. This produces vibrational spectra with the highest time resolution ever reported. Time-resolved resonance Raman spectroscopy has been recognized as a powerful method for studying structures of transient species and electronic excited states. By applying the new methods to a polydiacetylene (PDA) crystal epitaxially grown on a KCl substrate, we could observe Raman spectrum of the exciton state in PDA with only 1.5 ps lifetime.
Ultrafast relaxation in conjugated polymers
01.01.1999
104680 byte
Aufsatz (Konferenz)
Elektronische Ressource
Englisch
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