Atomformfaktorbestimmung mit Elektronen

Mark, Hillery; Wierl, R.

doi:10.1007/bf01339959

Cited by 57 publications

(11 citation statements)

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“…The voltage was measured with an error of -~1,5~£ Owing to the given diameter of the primary beato, to the angular spread (semi-cone angle of angular spread was found to be 5.10 -4 radians) and to the multiple scattering occurring in the foil the rings ate broadened. The mean diameter of the rings was determined microscopically (that of some of lower intensities visually) and the scattering angles for maximum intensities as calculated and measured ate shown in the Table. The intensity ratios of individual rings are in qualitative agreement with those reported in the literature for lower energies [7,8]. Ring Thanks are due to Dr. P. SZAB‰ for helpful discussions.…”

supporting

confidence: 85%

Small-angle coherent scattering of 500 keV electrons

Berkes

Demeter

1960

Acta Physica

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supporting

confidence: 85%

Small-angle coherent scattering of 500 keV electrons

Berkes

Demeter

1960

Acta Physica

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“…An exposure time of 24 h was needed to record the diffraction pattern. A year later, Mark and Weirl112–114 recorded the first electron diffraction on the same gas, with an exposure time of minutes, because of the high scattering cross‐section of electrons (Table 1). Since then, electron diffraction has become the preferred tool for structural determination in the gas phase, and thousands of structures have been determined.…”

Section: Ultrafast X‐ray Diffraction and Spectroscopy: Applicationsmentioning

confidence: 99%

Electron and X‐Ray Methods of Ultrafast Structural Dynamics: Advances and Applications

Chergui¹,

Zewail²

2009

ChemPhysChem

214

164

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In this contribution, we highlight the state of the art in the determination of structures with ultrafast electrons and X-rays. We provide our perspectives and reflections on the principles, techniques and methods, and on applications from different disciplines, with some focus on physical, chemical and biological structures. Although this article is not a survey of all the work done with these techniques, it provides a comprehensive referencing to current research.

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“…The determination of molecular structure is a fundamental issue in chemistry, as molecular structure reflects or even determines the properties and reactivity of a molecule . Various experimental techniques, such as gas electron diffraction, microwave, infrared, Raman, electronic, and photoelectron spectroscopy, can be used for structure determination, leading to, for example, the so‐called r g , r a , r 0 , r z , r s , r m structures of different physical significance, which, for any given molecule, have different values. Hence, the concept of “structure” needs to be rather carefully defined.…”

Section: Introductionmentioning

confidence: 99%

Perturbative treatment of anharmonic vibrational effects on bond distances: An extended langevin dynamics method

Shen

et al. 2013

J Comput Chem

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In this work, we first review the perturbative treatment of an oscillator with cubic anharmonicity. It is shown that there is a quantum-classical correspondence in terms of mean displacement, mean-squared displacement, and the corresponding variance in the first-order perturbation theory, provided that the amplitude of the classical oscillator is fixed at the zeroth-order energy of quantum mechanics EQM (0). This correspondence condition is realized by proposing the extended Langevin dynamics (XLD), where the key is to construct a proper driving force. It is assumed that the driving force adopts a simple harmonic form with its amplitude chosen according to EQM (0), while the driving frequency chosen as the harmonic frequency. The latter can be improved by using the natural frequency of the system in response to the potential if its anharmonicity is strong. By comparing to the accurate numeric results from discrete variable representation calculations for a set of diatomic species, it is shown that the present method is able to capture the large part of anharmonicity, being competitive with the wave function-based vibrational second-order perturbation theory, for the whole frequency range from ∼4400 cm(-1) (H2 ) to ∼160 cm(-1) (Na2 ). XLD shows a substantial improvement over the classical molecular dynamics which ceases to work for hard mode when zero-point energy effects are significant.

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Atomformfaktorbestimmung mit Elektronen

Abstract: An Elektronen-Debye-Scherrer-Aufnahmen yon A]-, Ag-und Au-Folien werden Intensit~itsmessungen ausgefiihrt. Die Ergebnisse werden vergliehen mit der B e theschen Theorie, der Rutherfordschen Streuformel und den R/intgenatomformfaktoren.

Cited by 57 publications

References 0 publications

Small-angle coherent scattering of 500 keV electrons

Small-angle coherent scattering of 500 keV electrons

Electron and X‐Ray Methods of Ultrafast Structural Dynamics: Advances and Applications

Perturbative treatment of anharmonic vibrational effects on bond distances: An extended langevin dynamics method

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