title: Wavelength-modulated femtosecond stimulated Raman spectroscopy-approach towards automatic data processing.
abstract: A new wavelength modulator based on a custom-made chopper blade and a slit placed in the Fourier plane of a pulse shaper was used to detect explicitly the first derivative of the time-resolved femtosecond stimulated Raman spectroscopy (FSRS) signals. This approach resulted in an unprecedented reduction of the non-coherent background that results from population transfer by the Raman pump inherent to FSRS experiments. The method of Fourier peak filtering was implemented as a powerful tool for reducing both the remaining non-coherent and coherent background associated with FSRS experiments. The method was demonstrated on β-carotene and a similar synthetic aryl carotenoid. The experiments confirm earlier FSRS results on β-carotene but suggest some reinterpretation. Strong bleaching signals of ground state vibrations were observed and interpreted as an inseparable part of the time-resolved FSRS experiment. New long-lived Raman features were observed in β-carotene and the synthetic aryl carotenoid and assigned to a combination of conformational changes and solvent rearrangement. More complex wavelength modulation methods are proposed in the development of more robust FSRS experiments.
authors: Department of Physics and Astronomy, Faculty of Sciences, VU University, De Boelelaan 1081, 1081HV Amsterdam, The Netherlands.
authors: Miroslav
authors: M
authors: Kloz
authors: Rienk
authors: R
authors: van Grondelle
authors: John T M
authors: JT
authors: Kennis