title: Frequency modulated femtosecond stimulated Raman spectroscopy of ultrafast energy transfer in a donor-acceptor copolymer.
abstract: A Raman-pump frequency modulation scheme and an automated signal-processing algorithm are developed for improved collection of time-resolved femtosecond stimulated Raman spectra. Together, these two advancements remove the broad background signals endemic to FSRS measurements and retrieve signals with high sensitivity. We apply this frequency-modulated femtosecond stimulated Raman spectroscopy (FM-FSRS) to the characterization of ultrafast energy transport in a copolymer comprised of polystyrene linked oligo(phenylene-ethynylene) donor and thiophene-benzothiadiazole acceptor chromophores. After photoexcitation of the donor, ultrafast energy transfer is monitored by the decay of donor vibrational modes and simultaneous growth of acceptor modes. The FM-FSRS method shows clear advantages in signal-to-noise levels, mitigation of artifact features, and ease of data processing over the conventional FSRS technique.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA.
authors.forename: Erik M
authors.initials: EM
authors.lastname: Grumstrup
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Chen
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Vary
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Moran
authors.forename: Kirk S
authors.initials: KS
authors.lastname: Schanze
authors.forename: John M
authors.initials: JM
authors.lastname: Papanikolas
mesh_terms: D004735:Energy Transfer; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D013997:Time Factors
chemical_list: D011108:Polymers; D011137:Polystyrenes; C473966:poly(phenylene ethynylene)