Femtosecond Chemical Dynamics in Condensed Phases

Fleming, Graham R.; Joo, Taiha; Cho, M.

doi:10.1002/9780470141601.ch5

Cited by 25 publications

(12 citation statements)

References 55 publications

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“…9 To identify the origin of this striking intensity dependence, we carried out theoretical model simulations. Thirdorder nonlinear response theory predicts that a plot of the peak shift as a function of population time T follows closely the correlation function of transition energy fluctuation 10,11 and its signal amplitude is proportional to the cube of excitation intensity. The strong dependence on the intensity observed in this study thus goes beyond the third-order nonlinearity.…”

Section: Introductionmentioning

confidence: 97%

Dephasing in semiconducting single-walled carbon nanotubes induced by exciton-exciton annihilation

Abramavičius

Graham

et al. 2009

Phys. Rev. B

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Three-pulse photon echo peak-shift measurements were performed on semiconducting single-walled carbon nanotubes embedded in a polymer matrix at room temperature. We found a striking dependence of the peak shift on the excitation intensity. Numerical simulations based on an interacting-boson model demonstrate that the intensity dependence originates from a highly nonlinear optical response initiated by exciton-exciton annihilation.

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Section: Introductionmentioning

confidence: 97%

Dephasing in semiconducting single-walled carbon nanotubes induced by exciton-exciton annihilation

Abramavičius

Graham

et al. 2009

Phys. Rev. B

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“…The generation of semiclassical wave packet motion for molecular vibrations via sequential infrared multiphoton excitation is a powerful tool for the investigation of the quantum dynamics of photoinduced reactions for several reasons. 1, 30,31 Yet, detailed analyses of effects inherent to reduced dimensionality treatments and the errors that consequently arise from these approximations are rather rare. Second, sequential, quasiresonant multiphoton absorption in the infrared domain induces a vibrational motion that is easily recognizable both for its smoothly increasing amplitude and for being semiclassical, at least during an initial phase of the dynamics, before the wave packet spreads out because of anharmonicity or other intrinsic quantum mechanical effects.…”

Section: Introductionmentioning

confidence: 99%

Full-dimensional quantum dynamics of vibrationally highly excited NHD2

Marquardt

Sanrey

Gatti

et al. 2010

The Journal of Chemical Physics

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We report on full-dimensional vibrational quantum dynamics of the highly excited ammonia isotopologue NHD(2) using a newly developed potential energy surface and the MCTDH program package. The calculations allow to realistically simulate an infrared laser induced stereomutation reaction at the pyramidal nitrogen atom in the femtosecond time domain. Our results allow for a thorough qualitative and quantitative understanding of infrared photoinduced stereomutation kinetics, the underlying quantum dynamics, and the reaction mechanisms. Comparison is made with a previous, reduced dimensionality study of the same reaction [R. Marquardt, M. Quack, I. Thanopulos, and D. Luckhaus, J. Chem. Phys. 118, 643 (2003)], and it is shown that slight variances of reduced spaces lead to significantly different kinetics. Because the quantum dynamics depends subtly on variances of reduced spaces, reduced dimensionality treatments are not reliable even for qualitative predictions of the stereomutation kinetics. The first direct comparison between the Multiconfigurational Time Dependent Hartree [M. H. Beck, A. Jäckle, G. A. Worth et al., Phys. Rep. 324, 1 (2000)] and Unimolecular Reactions Induced by Monochromatic Infrared Radiation [M. Quack and E. Sutcliffe, QCPE Bulletin 6, 98 (1986)] program packages on a specific, four dimensional quantum dynamical problem allows for their full validation in the present work.

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“…FCS is an ultrafast pump-probe technique that employs the bandwidth of femtosecond laser pulses to create and subsequently detect coherent vibrational motions in the sample of interest. The theoretical basis of this time-domain spectroscopy can be found elsewhere (74)(75)(76)(77)(78)(79)(80)(81)(82), so the details are not discussed here. However, one important theoretical aspect of the experiments is that, in principle, coherences can be created on both the excited-and ground-state potential energy surfaces.…”

Section: Introductionmentioning

confidence: 99%

Investigations of Vibrational Coherence in the Low-Frequency Region of Ferric Heme Proteins

Gruia

Kubo

Champion

2008

Biophysical Journal

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Femtosecond coherence spectroscopy is applied to a series of ferric heme protein samples. The low-frequency vibrational spectra that are revealed show dominant oscillations near 40 cm(-1). MbCN is taken as a typical example of a histidine-ligated, six-coordinate, ferric heme and a comprehensive spectroscopic analysis is carried out. The results of this analysis reveal a new heme photoproduct species, absorbing near 418 nm, which is consistent with the photolysis of the His(93) axial ligand. The photoproduct undergoes subsequent rebinding/recovery with a time constant of approximately 4 ps. The photoproduct lineshapes are consistent with a photolysis quantum yield of 75-100%, although the observation of a relatively strong six-coordinate heme coherence near 252 cm(-1) (assigned to nu(9) in the MbCN Raman spectrum) suggests that the 75% lower limit is much more likely. The phase and amplitude excitation profiles of the low-frequency mode at 40 cm(-1) suggest that this mode is strongly coupled to the MbCN photoproduct species and it is assigned to the doming mode of the transient penta-coordinated material. The absolute phase of the 40 cm(-1) mode is found to be pi/2 on the red side of 418 nm and it jumps to 3pi/2 as excitation is tuned to the blue side of 418 nm. The absolute phase of the 40 cm(-1) signal is not explained by the standard theory for resonant impulsive stimulated Raman scattering. New mechanisms that give a dominant momentum impulse to the resonant wavepacket, rather than a coordinate displacement, are discussed. The possibilities of heme iron atom recoil after photolysis, as well as ultrafast nonradiative decay, are explored as potential ways to generate the strong momentum impulse needed to understand the phase properties of the 40 cm(-1) mode.

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Femtosecond Chemical Dynamics in Condensed Phases

Cited by 25 publications

References 55 publications

Dephasing in semiconducting single-walled carbon nanotubes induced by exciton-exciton annihilation

Dephasing in semiconducting single-walled carbon nanotubes induced by exciton-exciton annihilation

Full-dimensional quantum dynamics of vibrationally highly excited NHD2

Investigations of Vibrational Coherence in the Low-Frequency Region of Ferric Heme Proteins

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