title: On the Resolution Limit of Femtosecond Stimulated Raman Spectroscopy: Modelling Fifth-Order Signals with Overlapping Pulses.
abstract: Femtosecond stimulated Raman scattering (FSRS) spectroscopy is a powerful pump-probe technique that can track electronic and vibrational dynamics with high spectral and temporal resolution. The investigation of extremely short-lived species, however, implies deciphering complex signals and is ultimately hampered by unwanted nonlinear effects once the time resolution limit is approached and the pulses overlap temporally. Using the loop diagrams formalism we calculate the fifth-order response of a model system and address the limiting case where the relevant dynamics timescale is comparable to the pump-pulse duration and, consequently, the pump and the probe overlap temporally. We find that in this regime, additional diagrams that do not contribute for temporally well separated pulses need to be taken into account, giving rise to new time-dependent features, even in the absence of photoinduced dynamics and for negative delays.
authors.affiliation: Dipartimento di Fisica, Universitá di Roma "La Sapienza", I-00185, Roma, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Fumero
authors.affiliation: Dipartimento di Fisica, Universitá di Roma "La Sapienza", I-00185, Roma, Italy.|Dipartimento di Scienze Fisiche e Chimiche, Universitá degli Studi, dell'Aquila, I-67100, L'Aquila, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Batignani
authors.affiliation: Department of Chemistry, University of California, California, 92697-2025, Irvine, USA.
authors.forename: Konstantin E
authors.initials: KE
authors.lastname: Dorfman
authors.affiliation: Dipartimento di Fisica, Universitá di Roma "La Sapienza", I-00185, Roma, Italy.
authors.forename: Shaul
authors.initials: S
authors.lastname: Mukamel
authors.affiliation: Dipartimento di Fisica, Universitá di Roma "La Sapienza", I-00185, Roma, Italy. tullio.scopigno@phys.uniroma1.it.|Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, 295 Viale Regina Elena, I-00161, Roma, Italy. tullio.scopigno@phys.uniroma1.it.
authors.forename: Tullio
authors.initials: T
authors.lastname: Scopigno
keywords: Raman spectroscopy; femtochemistry; nonlinear optics; pump-probe spectroscopy; time-resolved spectroscopy