Experimental Detection of Branching at a Conical Intersection in a

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Experimental Detection of Branching at a Conical Intersection in a Highly Fluorescent Molecule Johanna Brazard, Laurie A. Bizimana, Tobias Gellen, William P. Carbery, and Daniel B. Turner J. Phys. Chem. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.jpclett.5b02476 • Publication Date (Web): 08 Dec 2015 Downloaded from http://pubs.acs.org on December 9, 2015

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The Journal of Physical Chemistry Letters

Experimental Detection of Branching at a Conical Intersection in a Highly Fluorescent Molecule Johanna Brazard, Laurie A. Bizimana, Tobias Gellen, William P. Carbery, and Daniel B. Turner∗ Department of Chemistry, New York University, 100 Washington Square East, New York NY 10003, USA E-mail: [email protected]

∗

To whom correspondence should be addressed

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Conical intersections have become a major focus in photochemistry and related fields since the 1990s. 1–3 A conical intersection is a point where adiabatic potential-energy surfaces are degenerate. At one of these special molecular configurations, the Born–Oppenheimer approximation fails and the singular nonadiabatic coupling can allow rapid and efficient crossings between adiabatic potential-energy surfaces. 4,5 Ultrafast time-resolved spectroscopy measurements can reveal these surface-crossing events experimentally by quantifying electronic population kinetics and coherent wavepacket motion. 6–11 Such measurements have established a ‘paradigm of photochemistry’, defined as the coherent movement of a wavepacket from one electronic surface to another signifying passage through a conical intersection. 12 Theoretical and computational studies reveal that nearly all molecules have conical intersections, and that they drive many important excited-state chemical processes. 13–17 There is now a broad appreciation of the importance of conical intersections, although much remains unknown about their mechanistic role in excited-state chemistry. 18–20 While conical intersections are predicted to be ubiquitous, condensed-phase experiments have concentrated on the handful of systems that produce conventional signatures such as high photoactivity, femtosecond electronic kinetics, or negligible fluorescence. 21 Such systems include retinal proteins, 22–26 DNA nucleobases, 27 and, more recently, pentacene derivatives. 28 These studies have demonstrated important roles of conical intersections in making or breaking bonds, as well as deactivation of electronic excited states; however, the multitude of systems that do not exhibit any of the conventional signatures remain largely unexplored. Methods that detect conical intersections even when their conventional signatures are absent would enable developments such as experimental mapping of potential-energy surface topography. 29–32 Here we use high-sensitivity transient absorption spectroscopy to detect a coherent surface-crossing event in a molecule that does not exhibit the conventional signatures of a conical intersection mentioned above. We introduce and use an analysis methodology, coherent wavepacket evolution analysis, that merges the ‘paradigm of photochemistry’ 12 with the established interpretation of co-

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herent oscillations. 33,34 Coherent oscillations in transient absorption spectra of molecules in solution—quantum beats—are typically signatures of time-resolved molecular vibrations. 33,35 Femtosecond laser pulses can create superpositions of vibrational levels on one or more electronic states. These coherent superpositions are nonstationary under the molecular Hamiltonian and therefore generate a time-dependent wavepacket that traverses the multidimensional potential-energy surface. In many molecules, initial excitation at the Franck–Condon region produces a wavepacket that quickly relaxes to a local minimum where it oscillates, yielding sinusoidal modulations of a transient absorption spectrum at the natural frequency of the vibrational mode. The spectrum of the femtosecond pulse strongly influences both the creation and detection processes of the coherent wavepacket. If the spectrum of the femtosecond pulse covers less than half of the absorption spectrum of the sample, one expects initial wavepacket oscillations on both the ground and excited electronic states. In contrast, a femtosecond pulse having a spectrum that covers the entire absorption spectrum of the sample is expected to produce an initial nonstationary wavepacket only on the electronic excited state. 36–39 To obtain chemical insight from the coherent oscillations, many researchers have used Fourier transforms to produce one-dimensional profiles of the amplitude and phase of each oscillation frequency as a function of probe wavelength. 31,40–42 As a consequence of interference effects, a coherent wavepacket that oscillates about the minimum of the ground-state (excited-state) potential will yield a node in the amplitude profile and a π shift in the phase profile at the wavelength of the absorption (fluorescence) maximum. 43–45 These nodes and phase shifts have been used as strong evidence supporting the notion that a conical intersection drives photoisomerization in rhodopsin. 12 While these studies have yielded tremendous insights, Fourier-domain methods involve mathematical integration over all of the coherent dynamics. Additional insights may be gained from the same datasets through time-frequency analysis, 46 which balances the mode-specificity of the Fourier-domain approach with the dynamic content of the time-resolved signal.

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(a)

wavelength

(b)

energy

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Sω0 (λ,τ)

λ max abs λ max fl

time

reaction coordinate

Figure 1: Schematic illustration of how coherent wavepacket evolution analysis detects coherent surface-crossing events. (a) Initial excitation (grey arrow) yields a wavepacket that oscillates in the excited adiabatic potential-energy surface until it proceeds through the conical intersection (yellow-green), after which it oscillates in the ground adiabatic potential-energy surface. (b) Sω0 (λ, τ ) signal initially contains a node at the fluoresence maximum. A new node appears at the absorption maximum after surface crossing via a conical intersection. Here we use coherent wavepacket evolution analysis to study the spectral dynamics of individual vibrational modes. This involves creating time-frequency representations of the coherent oscillations present in a transient absorption spectrum. For a specified oscillation frequency ω0 , the coherent wavepacket evolution signal, Sω0 (λ, τ ), is given by

Sω0 (λ, τ ) = e

+iω0 τ

×F

−1

h

H [ω − ω0 ] × F Sraw (λ, τ )

i τ

, ω

(1)

where Sraw (λ, τ ) is the raw spectrally resolved transient absorption dataset, F [. . . ] and F −1 [. . . ] are, respectively, the Fourier and inverse-Fourier transform functions, H [. . . ] is a window function, and ω0 is the natural frequency of the oscillator. The Fourier-shift factor, e+iω0 τ , removes the underlying, high-frequency oscillations (compare top and bottom panels of Fig. 4). Fig. 1 contains a general schematic that illustrates how coherent surfacecrossing events are manifest in the coherent wavepacket evolution signal, Sω0 (λ, τ ). For the projection of the reaction coordinate onto the coordinate for a coupling mode, 47,48 initial excitation should produce a node at the maximum of the fluorescence spectrum, λmax fl , and

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then, after propagation through a conical intersection to the ground electronic state, a node should appear at the maximum of the absorption spectrum, λmax abs . Decoherence reduces the amplitude of Sω0 (λ, τ ) as a function of the time delay. The coherent wavepacket evolution signal reveals the projection of the total reaction coordinate onto this normal vibrational coordinate as a function of the time delay between pump and probe pulses. To demonstrate the methodology, we will apply coherent wavepacket evolution analysis to a prototype oxazine dye molecule, cresyl violet perchlorate in methanol. Fig. 2 shows the absorption and fluorescence spectra, as well as the laser pulse spectrum. The absorption and fluorescence maxima are 596 nm and 621 nm, respectively. The laser pulse spectrum is broad enough to cover the entire fluorescence spectrum and almost the entire absorption spectrum. A fluorescence reference standard, cresyl violet has a fluorescence quantum yield of 54% in methanol. 49,50 Because conical intersections are thought to be a common feature of nonradiative decay, 2 we aimed to determine if one is present in cresyl violet. This molecule therefore serves as a test of coherent wavepacket evolution analysis to discover conical intersections in systems without their conventional signatures. 21 H2N

intensity (arb.)

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O

+ NH2

N – ClO4

500

600 700 wavelength (nm)

800

Figure 2: Absorption and fluorescence of cresyl violet perchlorate in methanol in dotted and dashed lines, respectively. The solid line is the laser pulse spectrum. The absorption and fluorescence maxima are at 596 and 621 nm, respectively. We used a high-sensitivity transient absorption spectrometer that can detect coherent oscillations with wavenumbers as high as 3300 cm−1 . We previously described the instrument and details of sample preparation. 51,52 The instrument uses shot-by-shot acquisitions, 6


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balanced detection, and the optimal averaging method; these features ensure that the nodes are not shifted to incorrect wavelengths. 51 For these measurements, the pulse duration was 6.9 fs (7.5 fs in-situ), and the beam waist was 19 µm. The pump and probe pulses were identical, and the sample concentration was about 0.1 mmol L−1 . The pump pulse energy

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650

DADS (%)

550 (a) ΔT/T (%) +4 0

750

−4

0

1

2

3

time (ps)

4

5

1.9 ps 3.2 ns

(b)

2 ×5 0

−2

550

650

750

wavelength (nm)

wavelength (nm)

was 15 nJ, and the probe intensity attenuation was 100×. wavelength (nm)

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550 (c) 600 ΔT/T (%) +0.3 0

650

−0.3

0

1

2

3

4

time (ps)

Figure 3: Transient-absorption spectra of cresyl violet perchlorate. (a) Raw spectrum contains no indication of conical-intersection dynamics. (b) Decay-associated difference spectra (DADS), where the amplitude of the 1.9-ps component has been amplified by 5. (c) Total coherence spectrum resulting from subtraction of population kinetics from raw spectrum. Fig. 3(a) presents the raw transient absorption spectrum, Sraw (λ, τ ). We extracted the underlying population decays using a global biexponential fit after dimensional reduction and noise filtering by single value decomposition. 53 Two components—1.9 ± 0.1 ps and 3.2 ns—were necessary and sufficient to fit the population decay kinetics. The decay-associated difference spectra in Fig. 3(b) suggest that the 3.2-ns component dominates the kinetics; spectral integration reveals that the 1.9-ps component accounts for only about 5% of the decay amplitude. Cancellation between overlapping excited-state absorption and stimulated emission signals from 610 nm to 650 nm implies that the 5% value is a lower bound for the nonradiative decay on this timescale. The residual nonradiative decay could result from other pathways that are outside our spectral window. Regardless, the population dynamics contain none of the striking features typically associated with conical intersections. 21 Subtraction of the population decays from the raw data for each emission wavelength leaves only the oscillations shown in Fig. 3(c), which arise from coherent wavepacket motion. As anticipated, there is no initial node at the absorption maximum, 596 nm, indicating that initial wavepacket oscillations in the ground electronic state are negligible. 36,38,43 The 7



coherence spectrum in Fig. 3(c) shows an initial node near 615 nm. Intriguingly, the initial node is not at 621 nm, the fluorescence maximum. This indicates that wavepacket oscillations about the global minimum of the excited electronic state are not initially dominant, which is distinct from recent work on photosynthetic pigment-protein complexes where the node appeared directly at the fluorescence maximum after a brief dynamic Stokes shift. 43,45 (a) wavelength (nm)

600

λ max abs λ max fl

620 640

(b) 600 ΔT/T (%) +0.08

620 640

0

(c) |ΔT/T| (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

600 nm

0.1 630 nm

0.05 0

0

1

2

3

time (ps)

Figure 4: Spectral dynamics of the 593 cm−1 mode of cresyl violet perchlorate. (a) Coherent wavepacket evolution signal without (a) and with (b) Fourier shift. The initial node at 615 nm disappears at about 1.7 ps, when it is replaced by three nodes. By 3.5 ps, one node settles at 596 nm, another at 610 nm, and a third at 621 nm. These nodes can be explained by branching at a conical intersection. Dashed arrows guide the eye. (c) Spectral dynamics at indicated wavelengths show more clearly the rise at about 750 fs. We then apply coherent wavepacket evolution analysis to the raw transient absorption spectrum and extract the 593 cm−1 signal. This strongly Raman-active mode is distinctive of the oxazine family, and it is associated with an in-plane vibrational mode of the phenyl ring. 54 Fig. 4(a) shows the signal without application of the Fourier shift. To ease interpretation of the spectral dynamics, we followed Eqn. (1) and Fourier-shifted the signal to suppress the underlying oscillations. Fig. 4(b) shows Sω0 (λ, τ ) for the 593 cm−1 mode. The signal reveals a delayed rise, peaking at about 750 fs, across broad regions of the spectrum on both sides of the node. The representative traces in Fig. 4(c) indicate this delayed rise more clearly. This is followed by a sudden loss of amplitude at about 1.5 ps. An initial node is present 8


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at 615 nm, but it disappears by about 1.7 ps. It is replaced by three nodes that spectrally shift after their onset. One node blue shifts toward 596 nm, the absorption maximum. A second node red shifts toward 610 nm. The third node is even further red shifted, eventually arriving at the fluorescence maximum of 621 nm. Although there are a few complicating features, the measured signal in Fig. 4(b) resembles the general schematic presented in Fig. 1(b). The blue-shifted node that settles at 596 nm indicates that a portion of the wavepacket transfers coherently to the ground electronic state. Following the paradigm, 12 this signature implies passage of the coherent wavepacket through a conical intersection. The observation of a time dependence to the blue shift suggests that the wavepacket takes some time to propagate from the point of the intersection to the bottom of the potential well. In terms of the branching space of the conical intersection, the 593 cm−1 signal behaves as predicted for a coupling mode. 26,47,48 As a low-frequency tuning mode brings the surfaces into resonance along this coupling coordinate, the coherent surface-crossing event occurs. Given the onset time of about 1.7 ps, coherent wavepacket evolution analysis suggests that the wavenumber of the tuning mode is about 20 cm−1 . This is consistent with the sudden disappearance of the node at about 3.5 ps: The wavepacket remains coherent long enough to encounter the conical intersection a second time, which leads to another surface-crossing event. This results in a second but out-of-phase wavepacket. 26 The two wavepackets destructively interfere, which causes the coherent oscillations and their spectral signatures to vanish more quickly than normal decoherence processes. Destructive interference could also occur on the excited state, leading to no additional wavepacket propagation and leaving population in the excited state to later fluoresce. In many replicate measurements, we have consistently detected a weak peak that appears near 17 cm−1 , which could be a signature of the tuning mode. An alternative explanation is that this is a signature of solvent reorganization. 14,55 However, the timescales for methanol 56 are 1.1 ps and 9 ps, which are inconsistent with the timescales observed in these measurements. The other two nodes reveal additional insights into the topography of the excited-state po-

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tential energy surfaces of cresyl violet. The most red-shifted node appears at the fluorescence maximum, strongly suggesting this fraction of the coherent wavepacket reaches the global minimum of the excited-state potential energy surface and is responsible for a portion of the fluorescence quantum yield. The central node, meaning the node with settles at about 610 nm, is more challenging to describe. Oxazine molecules are known for their charge-transfer states, and therefore the node at 610 nm may arise from coherent wavepacket propagation to an intramolecular charge-transfer state. It is intriguing that the onset of these signals are correlated to the onset of the ground-state coherent wavepacket signal. In principle, these splittings need not be correlated. Finally, there is a possibility that a close avoided crossing can lead to a coherent surface-crossing event, however no literature of which we are aware addresses this interpretation. As an internal control, we also applied coherent wavepacket evolution analysis to the other prominent coherent vibrational modes of the molecule. 51 The 2837 and 2950 cm−1 signals each show only one node at 655 nm, which corresponds to a shoulder in the fluorescence spectrum. These are Franck–Condon modes that involve the terminal N–H stretching vibrations. 54 The 340 and 520 cm−1 signals, both skeletal deformations, 54 each show only a single node at 615 nm. The 1042 cm−1 signal, due to C–H and NH2 rocking motions, reveals a single node at 625 nm. Thus, in comparison to the other coherent vibrational modes of cresyl violet, the spectral dynamics of the 593 cm−1 signal are unique. This is consistent with the notion that only certain vibrational modes form the branching space of the conical intersection. The brightest feature in Fig. 4 is only about 0.35 mOD, emphasizing the need for highsensitivity measurement capabilities. The weak nature of the features was motivation to determine whether changes in the data acquisition or data analysis methodologies affected the observation or location of these nodes. Through multiple measurements, we verified the signatures were not sensitive to pulse fluence or sample concentration. We also evaluated several filtering functions including rectangle and Gaussian, and also varying the width of the

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filter functions. The spectral features were not meaningfully affected by reasonable changes of the width or type of the applied spectral filter. One control measurement did significantly affect the spectral features. Adding a 0.5-mm thick UV fused silica window in the pump beam introduced slight positive temporal dispersion that eliminated the intriguing nodal pattern. These pulses will generate wavepackets with significantly less nuclear momentum, 57 which implies the nonadiabatic dynamics will be significantly weaker. 58 This control measurement supports the discussion above. We have introduced and applied coherent wavepacket evolution analysis to a prototype molecule. This method revealed a coherent surface-crossing event that occurs picoseconds after photoexcitation in a system for which conventional analyses give no indication of conicalintersection activity. These results advance the understanding of coherent wavepacket motion near conical intersections 12,24 and demonstrate that time-frequency representations are a useful analysis tool for transient absorption spectroscopy. These findings should motivate and guide future theoretical work on conical intersections in condensed-phase systems. Specifically, computational studies of cresyl violet that include nonadiabatic coupling and charge-transfer states could support and expand on the analysis. The method of coherent wavepacket evolution analysis complements other experimental techniques for detecting conical intersections in condensed-phase systems. 59,60 Given the proliferation of transient absorption spectrometers having sub-10 fs laser pulses and high sensitivity, there should be growing interest in applying coherent wavepacket evolution analysis.

Acknowledgements New York University supported this work through start-up funding. L. A. B. acknowledges the National Science Foundation for a Graduate Research Fellowship. We thank J. Dawlaty and R. Pensack for commenting on a draft of the manuscript.

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References (1) Bernardi, F.; Olivucci, M.; Robb, M. A. Potential Energy Surface Crossings in Organic Photochemistry. Chem. Soc. Rev. 1996, 25, 321–328. (2) Domcke, W.; Yarkony, D. R.; Köppel, H. Conical Intersections: Electronic Structure, Dynamics & Spectroscopy; World Scientific Publishing, 2004. (3) Worth, G. A.; Cederbaum, L. S. Beyond Born-Oppenheimer: Molecular Dynamics Through a Conical Intersection. Annu. Rev. Phys. Chem. 2004, 55, 127–158. (4) Teller, E. The Crossing of Potential Energy Surfaces. J. Phys. Chem. 1937, 41, 109–116. (5) Jasper, A. W.; Zhu, C.; Nangia, S.; Truhlar, D. G. Introductory Lecture: Nonadiabatic Effects in Chemical Dynamics. Faraday Discussions 2004, 127, 1–22. (6) Stock, G. Classical Description of Nonadiabatic Photoisomerization Processes and Their Real-Time Detection via Femtosecond Spectroscopy. J. Chem. Phys. 1995, 103, 10015– 10029. (7) Domcke, W.; Stock, G. Theory of Ultrafast Nonadiabatic Excited-State Processes and Their Spectroscopic Detection in Real Time. Adv. Chem. Phys. 1997, 100, 1–169. (8) Blanchet, V.; Zgierski, M. Z.; Seideman, T.; Stolow, A. Discerning Vibronic Molecular Dynamics using Time-Resolved Photoelectron Spectroscopy. Nature 1999, 401, 52–54. (9) Farrow, D. A.; Qian, W.; Smith, E. R.; Ferro, A. A.; Jonas, D. M. Polarized PumpProbe Measurements of Electronic Motion via a Conical Intersection. J. Chem. Phys. 2008, 128, 144510. (10) Petit, A. S.; Subotnik, J. E. Calculating Time-Resolved Differential Absorbance Spectra for Ultrafast Pump-Probe Experiments with Surface Hopping Trajectories. J. Chem. Phys. 2014, 141, 154108.

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Page 12 of 18

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(11) Lehman, J. H.; Lester, M. I. Dynamical Outcomes of Quenching: Reflections on a Conical Intersection. Annu. Rev. Phys. Chem. 2014, 65, 537–555. (12) Wang, Q.; Schoenlein, R. W.; Peteanu, L. A.; Mathies, R. A.; Shank, C. V. Vibrationally Coherent Photochemistry in the Femtosecond Primary Event of Vision. Science 1994, 266, 422–424. (13) Yarkony, D. R. Conical Intersections: The New Conventional Wisdom. J. Phys. Chem. A 2001, 105, 6277–6293. (14) Toniolo, A.; Granucci, G.; Mart´ınez, T. J. Conical Intersections in Solution: A QM/MM Study Using Floating Occupation Semiempirical Configuration Interaction Wave Functions. J. Phys. Chem. A 2003, 107, 3822–3830. (15) Matsika, S.; Krause, P. Nonadiabatic Events and Conical Intersections. Annu. Rev. Phys. Chem. 2011, 62, 621–643. (16) Schapiro, I.; Melaccio, F.; Laricheva, E. N.; Olivucci, M. Using the Computer to Understand the Chemistry of Conical Intersections. Photochem. Photobiol. Sci. 2011, 10, 867–886. (17) Domcke, W.; Yarkony, D. Role of Conical Intersections in Molecular Spectroscopy and Photoinduced Chemical Dynamics. Annu. Rev. Phys. Chem. 2012, 63, 325–352. (18) Levine, B. G.; Mart´ınez, T. J. Isomerization Through Conical Intersections. Annu. Rev. Phys. Chem. 2007, 58, 613–634. (19) Yarkony, D. R. Nonadiabatic Quantum Chemistry—Past, Present, and Future. Chem. Rev. 2012, 112, 481–498. (20) Tavernelli, I. Nonadiabatic Molecular Dynamics Simulations: Synergies between Theory and Experiments. Acc. Chem. Res. 2015, 48, 792–800.

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(21) Haas, Y.; Zilberg, S. Photochemistry by Conical Intersections: A Practical Guide for Experimentalists. J. Photochem. Photobio. A 2001, 144, 221–228. (22) Schoenlein, R. W.; Peteanu, L. A.; Mathies, R. A.; Shank, C. V. The First Step in Vision: Femtosecond Isomerization of Rhodopsin. Science 1991, 254, 412–415. (23) Kobayashi, T.; Saito, T.; Ohtani, H. Real-Time Spectroscopy of Transition States in Bacteriorhodopsin during Retinal Isomerization. Nature 2001, 414, 531–534. (24) Polli, D.; Altoe, P.; Weingart, O.; Spillane, K. M.; Manzoni, C.; Brida, D.; Tomasello, G.; Orlandi, G.; Kukura, P.; Mathies, R. A. et al. Conical Intersection Dynamics of the Primary Photoisomerization Event in Vision. Nature 2010, 467, 440– 443. (25) Zgrablić, G.; Novello, A. M.; Parmigiani, F. Population Branching in the Conical Intersection of the Retinal Chromophore Revealed by Multipulse Ultrafast Optical Spectroscopy. J. Am. Chem. Soc. 2012, 134, 955–961. (26) Schnedermann, C.; Liebel, M.; Kukura, P. Mode-Specificity of Vibrationally Coherent Internal Conversion in Rhodopsin during the Primary Visual Event. J. Am. Chem. Soc. 2015, 137, 2866–2891. (27) Middleton, C. T.; de La Harpe, K.; Su, C.; Law, Y. K.; Crespo-Hernández, C. E.; Kohler, B. DNA Excited-State Dynamics: From Single Bases to the Double Helix. Annu. Rev. Phys. Chem. 2009, 60, 217–239. (28) Musser, A. J.; Liebel, M.; Schnedermann, C.; Wende, T.; Kehoe, T. B.; Rao, A.; Kukura, P. Evidence for Conical Intersection Dynamics Mediating Ultrafast Singlet Exciton Fission. Nature Physics 2015, 11, 352–357. (29) Atchity, G. J.; Xantheas, S. S.; Ruedenberg, K. Potential Energy Surfaces near Intersections. J. Chem. Phys. 1991, 95, 1862–1876. 14


Page 14 of 18

Page 15 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(30) Robb, M. A.; Olivucci, M. Photochemical Processes: Potential Energy Surface Topology and Rationalization using VB Arguments. J. Photochem. Photobio. A 2001, 5737, 1–7. (31) Wand, A.; Kallush, S.; Shoshanim, O.; Bismuth, O.; Kosloff, R.; Ruhman, S. Chirp Effects on Impulsive Vibrational Spectroscopy: A Multimode Perspective. Phys. Chem. Chem. Phys. 2010, 12, 2149–2163. (32) Malhado, J. P.; Hynes, J. T. Photoisomerization for a Model Protonated Schiff Base in Solution: Sloped/Peaked Conical Intersection Perspective. J. Chem. Phys. 2012, 137, 22A543. (33) Vos, M. H.; Rappaport, F.; Lambry, J.-C.; Breton, J.; Martin, J.-L. Visualization of Coherent Nuclear Motion in a Membrane Protein by Femtosecond Spectroscopy. Nature 1993, 363, 320–325. (34) Mukamel, S. Principles of Nonlinear Optical Spectroscopy; Oxford University Press: New York, 1995. (35) Walmsley, I. A.; Wise, F. W.; Tang, C. L. On the Difference Between Quantum Beats in Impulsive Stimulated Raman Scattering and Resonance Raman Scattering. Chem. Phys. Lett. 1989, 154, 315–320. (36) Pollard, W. T.; Mathies, R. A. Analysis of Femtosecond Dynamic Absorption Spectra of Nonstationary States. Annu. Rev. Phys. Chem. 1992, 43, 497–523. (37) Tanimura, Y.; Mukamel, S. Temperature Dependence and Non-Condon Effects in Pump-Probe Spectroscopy in the Condensed Phase. J. Opt. Soc. Am. B 1993, 10, 2263–2268. (38) Jonas, D. M.; Bradforth, S. E.; Passino, S. A.; Fleming, G. R. Femtosecond Wavepacket

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Spectroscopy: Influence of Temperature, Wavelength, and Pulse Duration. J. Phys. Chem. 1995, 99, 2594–2608. (39) Liebel, M.; Kukura, P. Broad-Band Impulsive Vibrational Spectroscopy of Excited Electronic States in the Time Domain. J. Phys. Chem. Lett. 2013, 4, 1358–1364. (40) Kumar, A. T. N.; Rosca, F.; Widom, A.; Champion, P. M. Investigations of Amplitude and Phase Excitation Profiles in Femtosecond Coherence Spectroscopy. J. Chem. Phys. 2001, 114, 701–724. (41) Braun, M.; Sobotta, C.; D¨ urr, R.; Pulvermacher, H.; Malkmus, S. Analysis of Wave Packet Motion in Frequency and Time Domain: Oxazine 1. J. Phys. Chem. A 2006, 110, 97930–9800. (42) Rury, A. S.; Sorenson, S.; Driscoll, E.; Dawlaty, J. M. Electronic State-Resolved Electron–Phonon Coupling in an Organic Charge Transfer Material from Broadband Quantum Beat Spectroscopy. J. Phys. Chem. Lett. 2015, 6, 3560–3564. (43) McClure, S. D.; Turner, D. B.; Arpin, P. C.; Mirkovic, T.; Scholes, G. D. Coherent Oscillations in the PC577 Cryptophyte Antenna Occur in the Excited Electronic State. J. Phys. Chem. B 2014, 118, 1296–1308. (44) Bishop, M. M.; Roscioli, J. D.; Ghosh, S.; Mueller, J. J.; Shephard, N. C.; Beck, W. F. Vibrationally Coherent Preparation of the Transition State for Photoisomerization of the Cyanine Dye Cy5 in Water. J. Phys. Chem. B 2015, 119, 6905–6915. (45) Arpin, P. C.; Turner, D. B.; McClure, S. D.; Jumper, C. C.; Mirkovic, T.; Challa, J. R.; Lee, J.; Teng, C. Y.; Green, B. R.; Wilk, K. E. et al. Spectroscopic Studies of Cryptophyte Light Harvesting Proteins: Vibrations and Coherent Oscillations. J. Phys. Chem. B 2015, 119, 10025–10034.

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Page 16 of 18

Page 17 of 18

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(46) Oppenheim, A. V.; Willsky, A. S.; Hamid, S. Signals and Systems, 2nd ed.; Prentice Hall, 1996. (47) K¨ uhl, A.; Domcke, W. Multilevel Redfield Description of the Dissipative Dynamics at Conical Intersections. J. Chem. Phys. 2002, 116, 263–274. (48) Egorova, D.; Domcke, W. Quantum Dynamical Simulations of Ultrafast Photoinduced Electron-Transfer Processes. J. Photochem. Photobio. A 2004, 166, 19–31. (49) Kreller, D. I.; Kamat, P. V. Photochemistry of Sensitizing Dyes. Spectroscopic and Redox Properties of Cresyl Violet. J. Phys. Chem. 1991, 95, 4406–4410. (50) Isak, S. J.; Eyring, E. M. Fluorescence Quantum Yield of Cresyl Violet in Methanol and Water as a Function of Concentration. J. Phys. Chem. 1992, 96, 1738–1742. (51) Brazard, J.; Bizimana, L. A.; Turner, D. B. Accurate Convergence of TransientAbsorption Spectra using Pulsed Lasers. Rev. Sci. Instr. 2015, 86, 053106. (52) Bizimana, L. A.; Brazard, J.; Carbery, W. P.; Gellen, T.; Turner, D. B. Resolving Molecular Vibronic Structure using High-Sensitivity Two-Dimensional Electronic Spectroscopy. J. Chem. Phys. 2015, 143, 164203. (53) Henry, E.; Hofrichter, J. Single Value Decomposition: Application to Analysis of Experimental Data. Methods in Enzymology 1992, 210, 129–192. (54) Vogel, E.; Gbureck, A.; Kiefer, W. Vibrational Spectroscopic Studies on the Dyes Cresyl Violet and Coumarin 152. J. Mol. Structure 2000, 550-551, 177–190. (55) Kahlow, M. A.; Wlodzimierz, J.; Kang, T. J.; Barbara, P. F. Femtosecond Resolved Solvation Dynamics in Polar Solvents. J. Chem. Phys. 1988, 90, 151–158. (56) Maroncelli, M.; Fleming, G. R. Picosecond Solvation Dynamics of Coumarin 153: The Importance of Molecular Aspects of Solvation. J. Chem. Phys. 1987, 86, 6221–6239. 17



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(57) Bardeen, C. J.; Wang, Q.; Shank, C. V. Selective Excitation of Vibrational Wave Packet Motion Using Chirped Pulses. Phys. Rev. Lett. 1995, 75, 3410–3413. (58) Tannor, D. J. Introduction to Quantum Mechanics: A Time-Dependent Perspective; University Science Books, 2007. (59) Kim, S. Y.; Kim, C. H.; Park, M.; Ko, K. C.; Lee, J. Y.; Joo, T. Coherent Nuclear Wave Packets Generated by Ultrafast Intramolecular Charge-Transfer Reaction. J. Phys. Chem. Lett. 2012, 3, 2761–2766. (60) Oliver, T. A. A.; Fleming, G. R. Following Coupled Electronic-Nuclear Motion through Conical Intersections in the Ultrafast Relaxation of β-Apo-8’-carotenal. J. Phys. Chem. B 2015, 119, 11428–11441.

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Experimental Detection of Branching at a Conical Intersection in a

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