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Interpretation of the THz-THz-Raman Spectrum of Bromoform

Magdău, Ioan B. and Mead, Griffin J. and Blake, Geoffrey A. and Miller, Thomas F., III (2019) Interpretation of the THz-THz-Raman Spectrum of Bromoform. Journal of Physical Chemistry A, 123 (33). pp. 7278-7287. ISSN 1089-5639. doi:10.1021/acs.jpca.9b05165.

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Nonlinear THz-THz-Raman (TTR) liquid spectroscopy offers new possibilities for studying and understanding condensed-phase chemical dynamics. Although TTR spectra carry rich information about the systems under study, the response is encoded in a three-point correlation function comprising of both dipole and polarizability elements. Theoretical methods are necessary for the interpretation of the experimental results. In this work, we study the liquid-phase dynamics of bromoform, a polarizable molecule with a strong TTR response. Previous work based on reduced density matrix (RDM) simulations suggests that unusually large multiquanta dipole matrix elements are needed to understand the measured spectrum of bromoform. Here, we demonstrate that a self-consistent definition of the time coordinates with respect to the reference pulse leads to a simplified experimental spectrum. Furthermore, we analytically derive a parametrization for the RDM model by integrating the dipole and polarizability elements to the 4th order in the normal modes, and we enforce inversion symmetry in the calculations by numerically canceling the components of the response that are even with respect to the field. The resulting analysis eliminates the need to invoke large multiquanta dipole matrix elements to fit the experimental spectrum; instead, the experimental spectrum is recovered using RDM simulations with dipole matrix parameters that are in agreement with independent ab initio calculations. The fundamental interpretation of the TTR signatures in terms of coupled intramolecular vibrational modes remains unchanged from the previous work.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Mead, Griffin J.0000-0003-0067-4219
Blake, Geoffrey A.0000-0003-0787-1610
Miller, Thomas F., III0000-0002-1882-5380
Additional Information:© 2019 American Chemical Society. Received: June 4, 2019; Revised: July 19, 2019; Published: July 22, 2019. The authors thank Ralph Welsch, Ian Finneran, Matthew Welborn, and Philip Shushkov for helpful discussions, as well as Peter Hamm for sharing a copy of their forthcoming manuscript. This work was supported by the National Science Foundation (Grant CHE-1665467) and the Office of Naval Research (Grant N00014-10-1-0884). The authors declare no competing financial interest.
Group:Astronomy Department
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-10-1-0884
Issue or Number:33
Record Number:CaltechAUTHORS:20190722-154828594
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Official Citation:Interpretation of the THz-THz-Raman Spectrum of Bromoform. Ioan B. Magdău, Griffin J. Mead, Geoffrey A. Blake, and Thomas F. Miller, III. The Journal of Physical Chemistry A 2019 123 (33), 7278-7287 DOI: 10.1021/acs.jpca.9b05165
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97331
Deposited By: Tony Diaz
Deposited On:22 Jul 2019 23:33
Last Modified:16 Nov 2021 17:30

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