Computational Study of the One and Two Dimensional Infrared Spectra of a Vibrational Mode Strongly Coupled to Its Environment: Beyond the Cumulant and Condon Approximations

Hanna, Gabriel; Geva, Eitan

doi:10.1021/jp804120v

Cited by 24 publications

(61 citation statements)

References 146 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the shape of the vibrational potential during PT events is highly anharmonic, leading to a nonlinear dependence of transition dipole intensities on the solvation coordinate (34). When 20 tunes into resonance with the laser in the 2D IR measurement, its transition dipole is Ϸ2/3 that of the fundamental transition at equilibrium (see SI).…”

Section: Modeling Based On Empirical Valence Bond MD Simulationsmentioning

confidence: 99%

Observation of a Zundel-like transition state during proton transfer in aqueous hydroxide solutions

Roberts

Petersen

Ramasesha

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

114

150

View full text Add to dashboard Cite

It is generally accepted that the anomalous diffusion of the aqueous hydroxide ion results from its ability to accept a proton from a neighboring water molecule; yet, many questions exist concerning the mechanism for this process. What is the solvation structure of the hydroxide ion? In what way do water hydrogen bond dynamics influence the transfer of a proton to the ion? We present the results of femtosecond pump-probe and 2D infrared experiments that probe the O-H stretching vibration of a solution of dilute HOD dissolved in NaOD/D2O. Upon the addition of NaOD, measured pump-probe transients and 2D IR spectra show a new feature that decays with a 110-fs time scale. The calculation of 2D IR spectra from an empirical valence bond molecular dynamics simulation of a single NaOH molecule in a bath of H2O indicates that this fast feature is due to an overtone transition of Zundel-like H3O 2 ؊ states, wherein a proton is significantly shared between a water molecule and the hydroxide ion. Given the frequency of vibration of shared protons, the observations indicate the shared proton state persists for 2-3 vibrational periods before the proton localizes on a hydroxide. Calculations based on the EVB-MD model argue that the collective electric field in the proton transfer direction is the appropriate coordinate to describe the creation and relaxation of these Zundel-like transition states.Grotthuss mechanism ͉ 2D infrared spectroscopy P roton transfer in water is the process at the heart of biological redox chemistry and energy conversion processes such as photosynthesis and cellular respiration (1). Although its extraordinary speed and efficiency has generally been attributed to the rearrangement of O-H bonds that effectively move the charge rather than a specific proton, the water structure around the charge defect and the mechanism of translocation remain challenging to study experimentally. Researchers commonly discuss the solvated excess proton in terms of 2 limiting structures, the Eigen cation (2), a triply solvated hydronium ion (H 3 O ϩ ⅐3H 2 O), and the Zundel ion (3), a proton equally shared between 2 water molecules (H 5 O 2 ϩ or H 2 O⅐H⅐OH 2 ϩ ). However, the difference in energy between these 2 configurations is small, on the order of the energy of a hydrogen bond (2-3 kcal/mol) (4), which allows these structures to interconvert on femtosecond to picosecond time scales (5, 6). Thus, to meaningfully address the structure of the excess proton, one must also consider its dynamics. Similar questions related to this view of aqueous proton transfer (PT) exist for the hydroxide ion, whereby proton transfer occurs from water to OH Ϫ . What are the ion's limiting structures, and in what manner do changes in the water structure influence the ion's structural diffusion?Initial proposals for transport of the hydroxide ion described the process as the mirror image of that observed in acids (7) and postulated the existence of a stable H 3 O 2 Ϫ state (8). Ab initio simulations (9-11) suggest a different scenario in whi...

show abstract

Section: Modeling Based On Empirical Valence Bond MD Simulationsmentioning

confidence: 99%

Observation of a Zundel-like transition state during proton transfer in aqueous hydroxide solutions

Roberts

Petersen

Ramasesha

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

114

150

View full text Add to dashboard Cite

show abstract

“…In the N =8 case, the three peaks, in order of increasing intensity, are situated at approximately 1880, 2260, and 2530 cm −1 . The N =9 spectrum, which has one major peak at approximately 2540 cm −1 and a shoulder peak at approximately 2280 cm −1 , is similar in structure to the bulk phase spectrum 53. This can be taken as spectroscopic evidence of the onset of bulk phase behavior.…”

Section: Resultsmentioning

confidence: 74%

“…The model under study herein is essentially the nanocluster version of the Azzouz–Borgis model55 for a hydrogen‐bonded complex in a bulk polar solvent. As this model has been studied extensively,53–73 we only provide a brief description (the full details can be found in refs. 55, 57,60).…”

Section: Modelmentioning

confidence: 99%

“…16, the 1D IR spectra of a similar system confined in a spherical hydrophobic cavity were calculated by using mixed quantum–classical MD simulations. Both the 1D and 2D IR spectroscopy of the bulk version of the model studied herein have also been previously investigated by mixed quantum–classical dynamics and the spectral signatures of solvation and proton‐transfer dynamics in the 2D IR spectra were elucidated 53. 54 For example, the proton‐transfer rate in this complex was extracted from the time‐resolved 2D IR spectra by noting the timescale associated with the emergence of the off‐diagonal chemical exchange peaks.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Computational Study of the One‐ and Two‐Dimensional Infrared Spectra of a Proton‐Transfer Mode in a Hydrogen‐Bonded Complex Dissolved in a Polar Nanocluster

2013

Self Cite

View full text Add to dashboard Cite

The signatures of nanosolvation on the one- and two-dimensional (1D and 2D) IR spectra of a proton-transfer mode in a hydrogen-bonded complex dissolved in polar solvent molecule nanoclusters of varying size are elucidated by using mixed quantum-classical molecular dynamics simulations. For this particular system, increasing the number of solvent molecules successively from N=7 to N=9 initiates the transition of the system from a cluster state to a bulk-like state. Both the 1D and 2D IR spectra reflect this transition through pronounced changes in their peak intensities and numbers, but the time-resolved 2D IR spectra also manifest spectral features that uniquely identify the onset of the cluster-to-bulk transition. In particular, it is observed that in the 1D IR spectra, the relative intensities of the peaks change such that the number of peaks decreases from three to two as the size of the cluster increases from N=7 to N=9. In the 2D IR spectra, off-diagonal peaks are observed in the N=7 and N=8 cases at zero waiting time, but not in the N=9 case. It is known that there are no off-diagonal peaks in the 2D IR spectrum of the bulk version of this system at zero waiting time, so the disappearance of these peaks is a unique signature of the onset of bulk-like behavior. Through an examination of the trajectories of various properties of the complex and solvent, it is possible to relate the emergence of these off-diagonal peaks to an interplay between the vibrations of the complex and the solvent polarization dynamics.

show abstract

“…This model has been previously studied using the standard equilibrium ground state dynamics approach. 60 Both 1D-and 2D-IR spectroscopy have been used extensively to probe hydrogen-bonded systems. 47,[61][62][63][64][65][66][67][68][69][70][71][72][73][74] These experiments were accompanied by substantial theoretical and computational work, 42,59,66, but relatively little attention has been given to the signatures of nonequilibrium processes on the spectra.…”

Section: B Third Order Optical Responsementioning

confidence: 99%

Computational Study of the One and Two Dimensional Infrared Spectra of a Vibrational Mode Strongly Coupled to Its Environment: Beyond the Cumulant and Condon Approximations

Cited by 24 publications

References 146 publications

Observation of a Zundel-like transition state during proton transfer in aqueous hydroxide solutions

Observation of a Zundel-like transition state during proton transfer in aqueous hydroxide solutions

Computational Study of the One‐ and Two‐Dimensional Infrared Spectra of a Proton‐Transfer Mode in a Hydrogen‐Bonded Complex Dissolved in a Polar Nanocluster

CHAPTER 10. Quantum-Classical Liouville Dynamics of Condensed Phase Quantum Processes

Contact Info

Product

Resources

About