Saddle-point electrons in ionizing ion-atom collisions

Olson, R. E.; Gay, T. J.; Berry, H. G.; Hale, Edward B.; Irby, V. D.

doi:10.1103/physrevlett.59.36

Cited by 111 publications

(34 citation statements)

References 23 publications

(16 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In classical-trajectoryMonte Carlo (CTMC) calculations for p + H collisions Olson found electrons emitted in forward direction with nearly half of the projectile velocity. Olson (1983Olson ( , 1986) and Olson et al (1987) The velocity of the SP depends on both, the charges of the projectile as well as of the target nucleus. In the late 80s several measurements at collision energies between 50 and 100 keV/u done at Rolla (Irby et al 1988, Gay et al 1990 and Bariloche (Bernardi et al 1989(Bernardi et al , 1990 searched for that dependency to demonstrate the existence of the SP mechanism.…”

Section: Ionisation By Slow Projectiles: Saddle Point Electronsmentioning

confidence: 99%

Recoil-ion and electron momentum spectroscopy: reaction-microscopes

et al. 2003

View full text Add to dashboard Cite

Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions and electrons resulting from atomic or molecular fragmentation. In a unique combination, large solid angles close to π Microccopes -the "bubble chambers of atomic physics" -mark the decisive step forward to investigate many-particle quantum-dynamics occurring when atomic and molecular systems or even surfaces and solids are exposed to time-dependent external electromagnetic fields.The present review concentrates on just these latest technical developments and on at least four new classes of fragmentation experiments that have emerged within about the last five years. First, multi-dimensional images in momentum space brought unprecedented information on the dynamics of single-photon induced fragmentation of fixed-in-space molecules and on their structure. Second, a break-through in the investigation of highintensity short-pulse laser induced fragmentation of atoms and molecules has been achieved by using Reaction Microccopes. Third, for electron and ion-impact, the investigation of twoelectron reactions has matured to a state such that first fully differential cross sections (FDCS) are reported. Forth, comprehensive sets of FDCS for single ionisation of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies. In addition, a brief summary on the kinematics is provided at the beginning. Finally, the rich future potential of the method is shortly envisaged.2

show abstract

Section: Ionisation By Slow Projectiles: Saddle Point Electronsmentioning

confidence: 99%

Recoil-ion and electron momentum spectroscopy: reaction-microscopes

et al. 2003

View full text Add to dashboard Cite

show abstract

“…While negative projectiles such as electrons repel ionized target electrons, protons attract them, causing an enhancement in the doubly-differential cross sections at forward-ejection angles. This attraction results in two mechanisms, or "channels", for ionization unavailable to negativeprojectile collision complexes: charge transfer to the continuum (more recently labeled electron capture to the continuum-see, for example, Crooks and Rudd, 1970;Macek, 19701, in which the ejected electron has a velocity closely matching that of the projectile, and "saddlepoint" ionization (Olson et al, 1987), where electrons stranded on or near the saddle point of the electric potential between the positive target ion and receding projectile emerge with roughly half the projectile velocity. While ionization due to charge transfer to the continuum contributes little to the total cross section, the saddlepoint mechanism provides a significant fraction of the ionized electrons and is responsible for differences in the cross sections between, say, protons and antiprotons (see Kimura and Inokuti, 1988;Olson and Gay, 1988;Fainstein et al, 1989b;Schultz, 1989).…”

Section: Slow Incident Particlesmentioning

confidence: 99%

Electron production in proton collisions with atoms and molecules: energy distributions

1992

Self Cite

View full text Add to dashboard Cite

All known data on the energy distribution of secondary electrons from collisions of protons with atoms and molecules have been reviewed and differential cross sections have been collected. The two experimental methods used to obtain the data are discussed and possible sources of error pointed out. Theoretical treatments are reviewed and several methods of checking the consistency of the data are discussed. Two semiempirical models have been chosen to represent the differential cross sections, and parameters for these models are given which fit the average of the experimental data, subject to known constraints. Recommended values of differential cross sections are given for ten target gases by means of these models. All known data on the energy distribution of secondary electrons from collisions of protons with atoms and molecules have been reviewed and differential cross sections have been collected. The two experimental methods used to obtain the data are discussed and possible sources of error pointed out. Theoretical treatments are reviewed and several methods of checking the consistency of the data are discussed. Two semiempirical models have been chosen to represent the differential cross sections, and parameters for these models are given which fit the average of the experimental data, subject to known constraints. Recommended values of differential cross sections are given for ten target gases by means of these models. ©1992

show abstract

“…Thus the objection was made that no clean signature of a saddle-point mechanism was apparent. This objection is valid, but can be resolved by reemphasizing that the papers of Pieksma et al [20] and Olson et al [2] are really claiming different things. At low energy a specific saddle-point mechanism has been identified and the spectra bear out the predictions of a calculation based on this mechanism.…”

Section: Saddle-point Electrons At Intermediate Collision Energiesmentioning

confidence: 99%

“…Any backwash from CTC would generally satisfy the rather general defmition of saddle-point elecvons as advanced by Olson et 01. [2], but would not be characteristic of "uue" vf2 electrons that originate on or neat the saddle-point But another question arises in this context Visible on mms 0" spectra, both calculated and experimental, are. secondary mid-velocity maxima below the CTC cusp.…”

Section: Saddle-point Electrons At Intermediate Collision Energiesmentioning

confidence: 99%

“…over most of their ionizing trajectories, comparable forces from the He' ion and the receding proton. Olson et al [2,4] chose to call these mid-speed electrons "saddle-point" electrons because of their proximity, both in space and velocity space, to the actual Coulomb saddle point. By dividing the post-collision volume into three regions (see Table I), they were able to show that almost 60% of the ionized electrons are emitted in the middle saddle-point region for 60 keV proton energy.…”

Section: Saddle-point Electrons At Intermediate Collision Energiesmentioning

confidence: 99%

See 1 more Smart Citation