Perspective: On the relevance of slower-than-femtosecond time scales in chemical structural-dynamics studies

Coppens, Philip

doi:10.1063/1.4913362

Cited by 9 publications

(8 citation statements)

References 45 publications

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“…Such an improved Laue method, capable of producing excited-state structures at atomic resolution of high quality, is very promising for the development of dynamical structural science. Other examples are discussed in the review by Coppens …”

Section: Molecules In Crystalsmentioning

confidence: 99%

Photoinduced Structural Dynamics of Molecular Systems Mapped by Time-Resolved X-ray Methods

2017

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ABSTRACT:We review the tremendous advances in ultrafast X-ray science, over the past 15 years, making the best use of new ultrashort x-ray sources including table-top or large-scale facilities. Different complementary x-ray based techniques, including spectroscopy, scattering and diffraction, are presented. The broad and expanding spectrum of these techniques in the ultrafast time domain, is delivering new insight into the dynamics of molecular systems, of solutions, of solids and of Biosystems. Probing the time evolution of the electronic and structural degrees of freedom of these systems on the timescales of femtosecond to picoseconds delivers new insight into our understanding of dynamical matter.

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Section: Molecules In Crystalsmentioning

confidence: 99%

Photoinduced Structural Dynamics of Molecular Systems Mapped by Time-Resolved X-ray Methods

2017

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“…Important dynamics take place in this whole span of ranges. I have emphasized that slower than femtosecond studies should not be ignored if a comprehensive picture of the structural dynamics of a system is to be achieved (Coppens, 2015). The ultimate goal is illustrated in Fig.…”

Section: Final Remarksmentioning

confidence: 99%

The dramatic development of X-ray photocrystallography over the past six decades

Coppens¹

2017

Structural Dynamics

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“…As a developmental analogy, the Maxwell Boltzmann distribution for molecular velocities is necessarily consistent with the ideal gas law -yet the ideal gas law is mostly preferred when entering a description of gases. Desirable and inevitable consistency across broad timescales (Coppens, 2015) must here be moderated by a kind of artificial horizon (Jaynes, 1991). So we have sought to relieve analyses of temporal aspects where possible, at least for now.…”

Section: E4 Tests Of Scaling Lawsmentioning

confidence: 99%

The index of dispersion as a metric of quanta – unravelling the Fano factor

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Paziresh

Latham

et al. 2017

Acta Crystallogr Sect B

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In statistics, the index of dispersion (or variance-to-mean ratio) is unity (σ/〈x〉 = 1) for a Poisson-distributed process with variance σ for a variable x that manifests as unit increments. Where x is a measure of some phenomenon, the index takes on a value proportional to the quanta that constitute the phenomenon. That outcome might thus be anticipated to apply for an enormously wide variety of applied measurements of quantum phenomena. However, in a photon-energy proportional radiation detector, a set of M witnessed Poisson-distributed measurements {W, W,… W} scaled so that the ideal expectation value of the quantum is unity, is generally observed to give σ/〈W〉 < 1 because of detector losses as broadly indicated by Fano [Phys. Rev. (1947), 72, 26]. In other cases where there is spectral dispersion, σ/〈W〉 > 1. Here these situations are examined analytically, in Monte Carlo simulations, and experimentally. The efforts reveal a powerful metric of quanta broadly associated with such measurements, where the extension has been made to polychromatic and lossy situations. In doing so, the index of dispersion's variously established yet curiously overlooked role as a metric of underlying quanta is indicated. The work's X-ray aspects have very diverse utility and have begun to find applications in radiography and tomography, where the ability to extract spectral information from conventional intensity detectors enables a superior level of material and source characterization.

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Perspective: On the relevance of slower-than-femtosecond time scales in chemical structural-dynamics studies

Cited by 9 publications

References 45 publications

Photoinduced Structural Dynamics of Molecular Systems Mapped by Time-Resolved X-ray Methods

Photoinduced Structural Dynamics of Molecular Systems Mapped by Time-Resolved X-ray Methods

The dramatic development of X-ray photocrystallography over the past six decades

The index of dispersion as a metric of quanta – unravelling the Fano factor

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