Frequency Modulated Femtosecond Stimulated Raman Spectroscopy of Ultrafast Energy Transfer in a Donor–Acceptor Copolymer

Grumstrup, Erik M.; Chen, Zhuo; Vary, Ryan P.; Moran, Andrew M.; Schanze, Kirk S.; Papanikolas, John M.

doi:10.1021/jp404498u

Cited by 25 publications

(34 citation statements)

References 25 publications

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“…To achieve a fully tunable Raman pump pulse, several techniques have been developed in the past years. The conceptually simplest approach is to use a conventional femtosecond noncollinear optical parametric amplifier (NOPA) followed by a tunable spectral filter . On the downside, this approach suffers from a notoriously low conversion efficiency as most of the frequency converted light is actually filtered out.…”

Section: Methodsmentioning

confidence: 99%

“…Using a subsequent compression stage, this time resolution can be improved somewhat. For an initial pulse width of 35 fs, 40 fs second‐harmonic pulses are regularly achieved with prism compressors and 35 fs has been demonstrated by self‐compression in an Ar‐filled hollow‐core fiber . Alternatively, the fundamental pulses can be pre‐chirped using a chirped mirror pair …”

Section: Methodsmentioning

confidence: 99%

“…The final excited‐state spectrum is shown as trace (H). The residual baseline can further be removed, for example by polynomial fitting, spline interpolation or moving‐median filtering …”

Section: Methodsmentioning

confidence: 99%

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Femtosecond Stimulated Raman Spectroscopy

2016

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Femtosecond stimulated Raman spectroscopy (FSRS) is an ultrafast nonlinear optical technique that provides vibrational structural information with high temporal (sub-50 fs) precision and high spectral (10 cm(-1) ) resolution. Since the first full demonstration of its capabilities ≈15 years ago, FSRS has evolved into a mature technique, giving deep insights into chemical and biochemical reaction dynamics that would be inaccessible with any other technique. It is now being routinely applied to virtually all possible photochemical reactions and systems spanning from single molecules in solution to thin films, bulk crystals and macromolecular proteins. This review starts with an historic overview and discusses the theoretical and experimental concepts behind this technology. Emphasis is put on the current state-of-the-art experimental realization and several variations of FSRS that have been developed. The unique capabilities of FSRS are illustrated through a comprehensive presentation of experiments to date followed by prospects.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Femtosecond Stimulated Raman Spectroscopy

2016

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“…Of course, undesired signal components that are generated by the subsets of the incoming beams (e.g., pump-probe and SRS) can always be eliminated by chopping the incident beams and/or by modulating the frequency of the narrowband pulse. [17][18][19] The magnitude of the background depends on the particular properties of the sample and the frequencies of the Raman pump and Stokes pulses. These laser pulses are often tuned into electronic resonance (or pre-resonance) with the photoproduct, where the equilibrium system is transparent.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond stimulated Raman spectroscopy by six-wave mixing

Molesky

Guo

Moran

2015

The Journal of Chemical Physics

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Femtosecond Stimulated Raman Spectroscopy (FSRS) is motivated by the knowledge of the molecular geometry changes that accompany sub-picosecond chemical reactions. The detection of vibrational resonances throughout the entire fingerprint region of the spectrum with sub-100-fs delay precision is fairly straightforward to accomplish with the FSRS technique. Despite its utility, FSRS must contend with substantial technical challenges that stem from a large background of residual laser light and lower-order nonlinearities when all laser pulses are electronically resonant with the equilibrium system. In this work, a geometry based on five incident laser beams is used to eliminate much of this undesired background in experiments conducted on metmyoglobin. Compared to a three-beam FSRS geometry with all electronically resonant laser pulses, the five-beam approach described here offers major improvements in the data acquisition rate, sensitivity, and background suppression. The susceptibility of the five-beam geometry to experimental artifacts is investigated using control experiments and model calculations. Of particular concern are undesired cascades of third-order nonlinearities, which are known to challenge FSRS measurements carried out on electronically off-resonant systems. It is generally understood that "forbidden" steps in the desired nonlinear optical processes are the origin of the problems encountered under off-resonant conditions. In contrast, the present experiments are carried out under electronically resonant conditions, where such unfortunate selection rules do not apply. Nonetheless, control experiments based on spectroscopic line shapes, signal phases, and sample concentrations are conducted to rule out significant contributions from cascades of third-order processes. Theoretical calculations are further used to estimate the relative intensities of the direct and cascaded responses. Overall, the control experiments and model calculations presented in this work suggest promise for multidimensional resonance Raman investigations of heme proteins.

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“…[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Modern fifth-order electronically resonant Raman spectroscopies are usually conducted with a pump-probe sequence in mind. The experiments begin when an "actinic" pump pulse initiates photochemical dynamics (e.g., ring-opening, electron transfer, and proton transfer).…”

Section: Introductionmentioning

confidence: 99%

Perspective: Two-dimensional resonance Raman spectroscopy

Molesky

Guo

Cheshire

et al. 2016

The Journal of Chemical Physics

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Two-dimensional resonance Raman (2DRR) spectroscopy has been developed for studies of photochemical reaction mechanisms and structural heterogeneity in complex systems. The 2DRR method can leverage electronic resonance enhancement to selectively probe chromophores embedded in complex environments (e.g., a cofactor in a protein). In addition, correlations between the two dimensions of the 2DRR spectrum reveal information that is not available in traditional Raman techniques. For example, distributions of reactant and product geometries can be correlated in systems that undergo chemical reactions on the femtosecond time scale. Structural heterogeneity in an ensemble may also be reflected in the 2D spectroscopic line shapes of both reactive and non-reactive systems. In this perspective article, these capabilities of 2DRR spectroscopy are discussed in the context of recent applications to the photodissociation reactions of triiodide and myoglobin. We also address key differences between the signal generation mechanisms for 2DRR and off-resonant 2D Raman spectroscopies. Most notably, it has been shown that these two techniques are subject to a tradeoff between sensitivity to anharmonicity and susceptibility to artifacts. Overall, recent experimental developments and applications of the 2DRR method suggest great potential for the future of the technique. Published by AIP Publishing. [http://dx

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Frequency Modulated Femtosecond Stimulated Raman Spectroscopy of Ultrafast Energy Transfer in a Donor–Acceptor Copolymer

Cited by 25 publications

References 25 publications

Femtosecond Stimulated Raman Spectroscopy

Femtosecond Stimulated Raman Spectroscopy

Femtosecond stimulated Raman spectroscopy by six-wave mixing

Perspective: Two-dimensional resonance Raman spectroscopy

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