Accessing Excited State Molecular Vibrations by Femtosecond Stimulated Raman Spectroscopy

Abstract

Excited state vibrations are crucial for determining the photophysical and photochemical properties of molecular compounds. Stimulated Raman scattering can coherently stimulate and probe molecular vibrations with optical pulses, but it is generally restricted to ground state properties. Working under resonance conditions enables cross-section enhancement and selective excitation to a targeted electronic level but is hampered by an increased signal complexity due to the presence of overlapping spectral contributions. Here, we show how detailed information about ground and excited state vibrations can be disentangled by exploiting the relative time delay between Raman and probe pulses to control the excited state population, combined with a diagrammatic formalism to dissect the pathways concurring with the signal generation. The proposed method is then exploited to elucidate the vibrational properties of the ground and excited electronic states in the paradigmatic case of cresyl violet. We anticipate that the presented approach holds the potential for selective mapping of the reaction coordinates pertaining to transient electronic stages implied in photoactive compounds.

Stimulated Raman lineshapes in the large light-matter interaction limit

“…In order to record the spectra of successive probe pulses in presence and in absence of the RP, a synchronized chopper blocks the RP at 500 Hz. Further details on the experimental setup are reported in [43,44,46].…”

Modulated Noncollinear Optical Parametric Amplifier Output Induced by Stimulated Raman Scattering

“…The shortened titles of them are "Mode-specific excited state dynamics based on Raman loss spectroscopy" [39] and "Snapshot of structure during phonon creation with ultrafast Raman spectroscopy" [40], and "Ultrashort laser-driven stable-buckling of blisters in chirped mirror" [41] are some examples of them. There are other important papers to be mentioned such as [42][43][44][45][46].…”

Noises investigations and image denoising in femtosecond stimulated Raman scattering microscopy

“…In the literature of SRS, great attention is given to technological and application advances, while the investigations of noise are often overlooked, although SNR is a crucial issue not only for biological imaging, but also for spectroscopic applications [25,26]. The hardware characterizations, usually, are carried out to assess the shot noise condition [27][28][29][30][31][32].…”