Lez #51+52 RIKES Imaging

 We described the basics of RIKES: a vibrationally resonant combination of pump and stokes can induce optical anisotropy which generates an electric field along a direction orthogonal to the incoming stokes, via a four wave mixing process. This effect can be homodyne detected, or via balanced detection, to measure separately the real and imaginary parts of the non linear susceptibility.

Lez #49+50 CARS and SRS imaging, background suppression stategies

We have seen how to implement CARS and SRS imaging and what are pro and cons of the two approaches. We discussed different strategies to suppress non resonant background accompanying CARS. 

Secondo Esonero

Lez #47+48 Imaging lineare e non lineare

We have seen the working principle of an imaging system based on linear and non-linear effects, with and without vibrational sensitivity

Lez #45+46 Esercitazione pre esonero II

Lez #43+44 Esercitazione pre esonero I

Lez #41+42 FSRS principles: tracking ultrafast reactions in biomolecules II

We discussed 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 

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.