Electron excitation in atoms and molecules by neutron-nucleus scattering

Lovesey, S. W.; Bowman, C.D.; Johnson, R. G.

doi:10.1007/bf01441296

Cited by 21 publications

(9 citation statements)

References 3 publications

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“…However, it is indeed possible to excite electrons in a NN collision as Lovesey and co-workers 25 and Reiter and Platzman 26 suggest. Actually, the idea dates back to 1939, when Migdal investigated what happens when an atom in its ground state receives an impulse that increases its velocity by v, in the limit that the impulse duration is very short compared with the electron period and with a / v, where a is the dimension of the atom.…”

Section: Electronic Excitation In a Neutron-nuclear Collisionmentioning

confidence: 94%

Breakdown of the Born-Oppenheimer description explains neutron Compton-scattering anomaly

Gidopoulos

2005

Phys. Rev. B

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Several neutron Compton scattering experiments reveal an apparent drop of the proton cross section when the collision time q is around 1 fs. Such small q corresponds to a large energy spread of the proton wave packet after collision, allowing it to access excited electronic levels. This nonadiabatic excitation of electrons leads to a distortion of the shape of the neutron scattering response function with some redistribution of intensity at energies higher than the nuclear recoil energy and a slight shift of the main neutron intensity peak to lower energies.

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Section: Electronic Excitation In a Neutron-nuclear Collisionmentioning

confidence: 94%

Breakdown of the Born-Oppenheimer description explains neutron Compton-scattering anomaly

Gidopoulos

2005

Phys. Rev. B

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“…To complete the connection with previous calculations of the cross-section [3] note that (j' = l,j = 2), (~) Q.A 21 = iQ.R J dr <p 2 (r,R)<p 1 (r,R+ g R) .…”

Section: Neutron Cross-section : Non-degenerate Levelsmentioning

confidence: 84%

“…This situation is likely to be realized in the majority of cases. In consequence, the cross-section (6.3) is small: an explicit example is discussed in [3]. For nearly degenerate electronic states g need not be small.…”

Section: Neutron Cross-section : Non-degenerate Levelsmentioning

confidence: 99%

“…Here, we formulate the theory of neutron scattering by a molecule, accompanied by an electronic transition, using a language that displays the r6le of gauge potentials and geometric phases. We will draw on earlier work [3], adding to it these recent developments and the behaviour of the cross-section in the vicinity of a level crossing where it is very large.…”

Section: Introductionmentioning

confidence: 99%

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Geometric (Berry) phases in neutron molecular spectroscopy

Lovesey

1992

Phys. Scr.

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A theory of neutron scattering by nuclei in a molecule, accompanied by an electronic transition, is formulated with attention to gauge potentials and geometric phases in the Bom-Oppenheimer scheme. Non-degenerate and nearly degenerate electronic levels are considered. For nearly degenerate levels it is shown that, the cross-section is free of the singular structure which characterizes the corresponding gauge potential for the phase, and much larger than for well separated electronic states.

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“…There are several types of experiments in the field of condensed matter involving energy transfers in the eV region (hω > 0.5 eV), beyond the deep inelastic experiments discussed above [169,146]. Such experiments include the study of high (anharmonic) vibrational states in hydrides [170], of electronic transitions in rare earth metals and compounds [90], in molecules and insulators [171], semiconductors [172][173][174][175] and magnetic materials [176,177,82,178-180, 89,91]. Moreover, studies of the dynamics of paired electrons of inner filled s 2 shells of impurity atoms in metals, where the scattering is due to single electron excitations from the inner shell of the impurity to the free states of the metal, have been recently considered on the theoretical ground [181].…”

Section: High-energy Inelastic Neutron Scatteringmentioning

confidence: 99%

Electron volt neutron spectrometers

Pietropaolo

Senesi

2011

Physics Reports

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The advent of pulsed neutron sources has made available intense fluxes of epithermal neutrons (500 meV ≤ E≤100 eV). The possibility to open new investigations on condensed matter with eV neutron scattering techniques, is related to the development of methods, concepts and devices that drive, or are inspired by, emerging studies at this energy scale. Electron volt spectrometers have undergone continuous improvements since the construction of the first prototype instruments, but in the last decade major breakthroughs have been accomplished in terms of resolution and counting statistics, leading, for example, to the direct measurement of the proton 3-D Born-Oppenheimer potential in any material, or to quantitatively probe nuclear quantum effects in hydrogen bonded systems. This paper reports on the most effective methods and concepts for energy analysis and detection, as well as devices for the optimization of electron volt spectrometers for different applications. This is set in the context of the progress made up to date in instrument development. Starting from early stages of development of the technique, particular emphasis will be given to the Vesuvio eV spectrometer at the ISIS neutron source, the first spectrometer where extensive scientific, as well as research and development programmes have been carried out. The potential offered by this type of instrumentation, from single particle excitations to momentum distribution studies, is then put in perspective into the emerging fields of eV spectroscopy applied to cultural heritages and neutron irradiation effects in electronics

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Electron excitation in atoms and molecules by neutron-nucleus scattering

Cited by 21 publications

References 3 publications

Breakdown of the Born-Oppenheimer description explains neutron Compton-scattering anomaly

Breakdown of the Born-Oppenheimer description explains neutron Compton-scattering anomaly

Geometric (Berry) phases in neutron molecular spectroscopy

Electron volt neutron spectrometers

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