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Title: Two-dimensional Fourier transform electronic spectroscopy at a conical intersection

Abstract

We report measurement and modeling of two-dimensional (2D) electronic spectra of a silicon naphthalocyanine (SiNc) in benzonitrile, a system for which the polarization anisotropy reveals passage through a square-symmetric Jahn-Teller conical intersection in ∼100 fs [D. A. Farrow, W. Qian, E. R. Smith, A. A. Ferro, and D. M. Jonas, J. Chem. Phys. 128, 144510 (2008)]. The measured 2D Fourier transform (FT) spectra indicate loss of electronic coherence on a similar timescale. The 2D spectra arising from femtosecond vibronic dynamics through the conical funnel are modeled by full non-adiabatic treatment of the coupled electronic and vibrational dynamics for a pair of un-damped Jahn-Teller active vibrations responsible for both electronic decoherence and population transfer. Additional damped Jahn-Teller active modes that can cause only decoherence or population transfer are treated with analytical response functions that can be incorporated into the numerical non-adiabatic calculation by exploiting symmetry assignment of degenerate vibronic eigenstates to one of two electronic states. Franck-Condon active totally symmetric modes are incorporated analytically. The calculations reveal that these conical intersection dynamics alone are incapable of destroying the coherence of the initially prepared wavepacket on the experimentally observed timescale and predict an unobserved recurrence in the photon echo slice at ∼200more » fs. Agreement with the experimental two-dimensional electronic spectra necessitates a role for totally symmetric vibrational dynamics in causing the echo slice to decay on a ∼100 fs timescale. This extended model also reproduces the ∼100 fs ultrafast electronic anisotropy decay in SiNc when an “asymmetric solvation mode” with a small stabilization energy of ∼2 cm{sup −1} is included. Although calculations show that inhomogeneities in the energy gap between excited states can broaden the anti-diagonal 2D lineshape, the anti-diagonal width is dominated by totally symmetric vibrational motions in SiNc. For this shallow conical intersection, the non-adiabatic dynamics destroy electronic coherence more slowly than they destroy electronic alignment.« less

Authors:
; ;
Publication Date:
OSTI Identifier:
22253370
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 140; Journal Issue: 12; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANISOTROPY; EXCITED STATES; FOURIER TRANSFORMATION; JAHN-TELLER EFFECT; POLARIZATION; RESPONSE FUNCTIONS; SIMULATION; SPECTRA; SPECTROSCOPY; STABILIZATION

Citation Formats

Kitney-Hayes, Katherine A., Ferro, Allison A., Tiwari, Vivek, and Jonas, David M., E-mail: david.jonas@colorado.edu. Two-dimensional Fourier transform electronic spectroscopy at a conical intersection. United States: N. p., 2014. Web. doi:10.1063/1.4867996.
Kitney-Hayes, Katherine A., Ferro, Allison A., Tiwari, Vivek, & Jonas, David M., E-mail: david.jonas@colorado.edu. Two-dimensional Fourier transform electronic spectroscopy at a conical intersection. United States. doi:10.1063/1.4867996.
Kitney-Hayes, Katherine A., Ferro, Allison A., Tiwari, Vivek, and Jonas, David M., E-mail: david.jonas@colorado.edu. Fri . "Two-dimensional Fourier transform electronic spectroscopy at a conical intersection". United States. doi:10.1063/1.4867996.
@article{osti_22253370,
title = {Two-dimensional Fourier transform electronic spectroscopy at a conical intersection},
author = {Kitney-Hayes, Katherine A. and Ferro, Allison A. and Tiwari, Vivek and Jonas, David M., E-mail: david.jonas@colorado.edu},
abstractNote = {We report measurement and modeling of two-dimensional (2D) electronic spectra of a silicon naphthalocyanine (SiNc) in benzonitrile, a system for which the polarization anisotropy reveals passage through a square-symmetric Jahn-Teller conical intersection in ∼100 fs [D. A. Farrow, W. Qian, E. R. Smith, A. A. Ferro, and D. M. Jonas, J. Chem. Phys. 128, 144510 (2008)]. The measured 2D Fourier transform (FT) spectra indicate loss of electronic coherence on a similar timescale. The 2D spectra arising from femtosecond vibronic dynamics through the conical funnel are modeled by full non-adiabatic treatment of the coupled electronic and vibrational dynamics for a pair of un-damped Jahn-Teller active vibrations responsible for both electronic decoherence and population transfer. Additional damped Jahn-Teller active modes that can cause only decoherence or population transfer are treated with analytical response functions that can be incorporated into the numerical non-adiabatic calculation by exploiting symmetry assignment of degenerate vibronic eigenstates to one of two electronic states. Franck-Condon active totally symmetric modes are incorporated analytically. The calculations reveal that these conical intersection dynamics alone are incapable of destroying the coherence of the initially prepared wavepacket on the experimentally observed timescale and predict an unobserved recurrence in the photon echo slice at ∼200 fs. Agreement with the experimental two-dimensional electronic spectra necessitates a role for totally symmetric vibrational dynamics in causing the echo slice to decay on a ∼100 fs timescale. This extended model also reproduces the ∼100 fs ultrafast electronic anisotropy decay in SiNc when an “asymmetric solvation mode” with a small stabilization energy of ∼2 cm{sup −1} is included. Although calculations show that inhomogeneities in the energy gap between excited states can broaden the anti-diagonal 2D lineshape, the anti-diagonal width is dominated by totally symmetric vibrational motions in SiNc. For this shallow conical intersection, the non-adiabatic dynamics destroy electronic coherence more slowly than they destroy electronic alignment.},
doi = {10.1063/1.4867996},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 12,
volume = 140,
place = {United States},
year = {2014},
month = {3}
}