Breaking of a bond: when is it statistical?

Yadav, Pankaj; Keshavamurthy, Srihari

doi:10.1039/c4fd00180j

Cited by 13 publications

(23 citation statements)

References 47 publications

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“…section II A for details). There are reasons to believe that these junctions are the seeds for classically nonstatistical dynamics [42,70,74]. It is therefore of some interest to investigate as to whether the signatures of such resonance junctions manifest in the corresponding quantum dynamics.…”

Section: Introductionmentioning

confidence: 99%

Relevance of the Resonance Junctions on the Arnold Web to Dynamical Tunneling and Eigenstate Delocalization

Karmakar

Keshavamurthy

2018

J. Phys. Chem. A

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In this work we study the competition and correspondence between the classical and quantum routes to intramolecular vibrational energy redistribution (IVR) in a three degrees of freedom model effective Hamiltonian. Specifically, we focus on the classical and the quantum dynamics near the resonance junctions on the Arnold web that are formed by intersection of independent resonances. The regime of interest models the IVR dynamics from highly excited initial states near dissociation thresholds of molecular systems wherein both classical and purely quantum, involving dynamical tunneling, routes to IVR coexist. In the vicinity of a resonance junction classical chaos is inevitably present and hence one expects the quantum IVR pathways to have a strong classical component as well. We show that with increasing resonant coupling strengths the classical component of IVR leads to a transition from coherent dynamical tunneling to incoherent dynamical tunneling. Furthermore, we establish that the quantum IVR dynamics can be predicted based on the structures on the classical Arnold web. In addition, we investigate the nature of the highly excited eigenstates in order to identify the quantum signatures of the multiplicity-2 junctions. For the parameter regimes studies herein, by projecting the eigenstates onto the Arnold web, we find that eigenstates in the vicinity of the junctions are primarily delocalized due to dynamical tunneling.

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Section: Introductionmentioning

confidence: 99%

Relevance of the Resonance Junctions on the Arnold Web to Dynamical Tunneling and Eigenstate Delocalization

Karmakar

Keshavamurthy

2018

J. Phys. Chem. A

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“…Outside of the context of Stark shift spectroscopy, long-lived vibrations are important in mediating chemical reactions in gas and condensed phase and in biomolecules. − There is interest in vibrational energy and thermal transport through molecules and molecular junctions, − including hydrocarbon chains and polyethylene glycol oligomers, in some studies with the aim of designing molecular systems that rectify vibrational energy − and thermal transport. − The nature and rate of energy and thermal transport in molecular systems are influenced by vibrational energy relaxation.…”

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confidence: 99%

Electric Fields Influence Intramolecular Vibrational Energy Relaxation and Line Widths

Maitra

Sarkar

Leitner

et al. 2021

J. Phys. Chem. Lett.

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Intramolecular vibrational energy relaxation (IVR) is fundamentally important to chemical dynamics. We show that externally applied electric fields affect IVR and vibrational line widths by changing the anharmonic couplings and frequency detunings between modes. We demonstrate this effect in benzonitrile for which prior experimental results show a decrease in vibrational line width as a function of applied electric field. We identify three major channels for IVR that depend on electric field. In the dominant channel, the electric field affects the frequency detuning, while in the other two channels, variation of anharmonic couplings as a function of field is the underlying mechanism. Consistent with experimental results, we show that the combination of all channels gives rise to reduced line widths with increasing electric field in benzonitrile. Our results are relevant for controlling IVR with external or internal fields and for gaining a more complete interpretation of line widths of vibrational Stark probes.

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“…The cyclic process of converting mechanical energy into rapidly expanding chemical reaction products underpins the detonation process in energetic solids. One potential mechanism of the buildup to detonation is the multiphonon up-pumping mechanism, whereby excitation of phonons from a shock front results in vibrational energy transfer (VET) to intramolecular modes through anharmonic coupling, ultimately leading to bond dissociation and chemical reaction. , The inverse process, vibrational cooling, dissipates excess vibrational energy into the bath of phonon modes and operates in tandem with any up-pumping processes occurring behind a shock front. , The strong mechanical-chemical coupling and sub-nanosecond dynamics in shock-induced chemistry challenges the applicability of customary statistical reaction treatments; , rather, these dynamics should be treated akin to other nonstatistical process. − Nonstatistical reaction dynamics can arise from phenomena such as strong anharmonicities in the potential energy surface, energy localization in a subset of vibrations, ,− and reactions with intrinsic “bottlenecks” in configuration space. , Herein, we report the dynamics of VET in polycrystalline pentaerythritol tetranitrate (PETN) on multiple, ultrafast time scales, finding some of the above signatures that would lead to nonstatistical reaction dynamics.…”

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confidence: 99%

Sub-picosecond to Sub-nanosecond Vibrational Energy Transfer Dynamics in Pentaerythritol Tetranitrate

Cole-Filipiak

Knepper

Wood

et al. 2020

J. Phys. Chem. Lett.

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The time scale associated with shock-induced detonation is a key property of energetic materials that remains poorly understood. Herein, we test aspects of one potential mechanism, the phonon up-pumping mechanism, where shock compression excites lattice phonon modes, transferring energy to intramolecular vibrations leading to chemical bond cleavage and reaction. Using ultrafast infrared pump−probe spectroscopy on pentaerythritol tetranitrate (PETN), we reveal sub-picosecond vibrational energy transfer (VET) from the photoexcited band at 1660 cm −1 into every other infrared-active mode in the probed frequency range 800−1800 cm −1 . Energy transfer processes remain incomplete at 150 ps. Computational predictions from density functional theory are used in tandem to elucidate VET pathways in PETN.

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Breaking of a bond: when is it statistical?

Cited by 13 publications

References 47 publications

Relevance of the Resonance Junctions on the Arnold Web to Dynamical Tunneling and Eigenstate Delocalization

Relevance of the Resonance Junctions on the Arnold Web to Dynamical Tunneling and Eigenstate Delocalization

Electric Fields Influence Intramolecular Vibrational Energy Relaxation and Line Widths

Sub-picosecond to Sub-nanosecond Vibrational Energy Transfer Dynamics in Pentaerythritol Tetranitrate

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