Lez #45+45 FSRS II Principles and applications (Vibrational cooling, internal conversion and conical intersections)

 We then discussed the case of MPT studied by FSRS, where an ultrafast motion outside the Franck Condon region is observed, followed by vibrational cooling and singlet to triplet internal conversion. This example illustrates the synergy among transient absorption, FSRS and DFT calculations.   

Lez #43+44 FSRS I Principles and applications (Heme proteins)

 We introduced the Femtosecond Stimulated Raman Scattering (FSRS) experimental scheme, where SRS is exploited to track the evolution of a system upon the photoexcitation of an Actinic pump pulse, preceding the Raman and Stokes pair. The experimental layout has been introduced and the temporal/spectral resolutions of FSRS have been compared with the time-resolved spontaneous Raman counterpart. Then we started to discuss the paradigmatic case of Myoglobin, where FSRS has been exploited to: i) interpret transient absorption experiments to discriminate between two possible contrasting scenarios related to the existence of transient electronic states vs vibrational cooling. ii) determine how the absorbed photon energy, initially stored in delocalized low frequency heme modes, is very efficiently funneled into specific high frequency modes prior to slow dissipation through the protein 

Lez #41+42 IRS signal, resonance effect in the blue-side SRS response

We investigated the IRS1 response under various resonance conditions, demonstrating that the resulting lineshapes - positive, negative, or dispersive- depend on the Raman pump wavelength relative to the sample absorption and the probed vibrational mode.

An expression for the IRS Raman gain was first derived for arbitrary spectral profiles of the Raman pump and probe pulses. The response was then analytically evaluated in the case of a monochromatic pump and an impulsive probe.

Lez #39+40 SRS signals

  Still on chi3 processes. We evaluated the SRS (RRS1 diagram) response in resonant and non resonant case, for monochromatic Raman pump and probe beams.