Kuramochi H, Tahara T. Tracking Ultrafast Structural Dynamics by Time-Domain Raman Spectroscopy.
J Am Chem Soc 2021;
143:9699-9717. [PMID:
34096295 PMCID:
PMC9344463 DOI:
10.1021/jacs.1c02545]
[Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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In traditional Raman spectroscopy,
narrow-band light is irradiated
on a sample, and its inelastic scattering, i.e., Raman scattering,
is detected. The energy difference between the Raman scattering and
the incident light corresponds to the vibrational energy of the molecule,
providing the Raman spectrum that contains rich information about
the molecular-level properties of the materials. On the other hand,
by using ultrashort optical pulses, it is possible to induce Raman-active
coherent nuclear motion of the molecule and to observe the molecular
vibration in real time. Moreover, this time-domain Raman measurement
can be combined with femtosecond photoexcitation, triggering chemical
changes, which enables tracking ultrafast structural dynamics in a
form of “time-resolved” time-domain Raman spectroscopy,
also known as time-resolved impulsive stimulated Raman spectroscopy.
With the advent of stable, ultrashort laser pulse sources, time-resolved
impulsive stimulated Raman spectroscopy now realizes high sensitivity
and a wide detection frequency window from THz to 3000 cm–1, and has seen success in unveiling the molecular mechanisms underlying
the efficient functions of complex molecular systems. In this Perspective,
we overview the present status of time-domain Raman spectroscopy,
particularly focusing on its application to the study of femtosecond
structural dynamics. We first explain the principle and a brief history
of time-domain Raman spectroscopy and then describe the apparatus
and recent applications to the femtosecond dynamics of complex molecular
systems, including proteins, molecular assemblies, and functional
materials. We also discuss future directions for time-domain Raman
spectroscopy, which has reached a status allowing a wide range of
applications.
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