摘要:

Electron momentum spectroscopy measurements of aluminum, copper and gold are presented. Data were taken for incoming electrons with an energy of 50 keV, and both outgoing electrons with an energy near 25 keV. In all cases we used an identical deconvolution procedure, which consistently removes all intensity at high energy loss values. However the intensity becomes vanishing small only for binding energies of about twice the bandwidth. The observed spectra compare well with many body calculations based on the cumulant expansion scheme ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449316

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Energies near the ionization threshold present a particular challenge for electron-impact ionization calculations. The effect of electron-electron correlation is stronger at lower energies where qualitatively different behavior in the differential cross sections has been predicted. Most of the predictions of the near-threshold behavior have come from semi-classical work. Besides the famous “Wannier threshold law” for the total ionization cross section there are predictions of a flattening of the energy-sharing cross section and a change in shape of the symmetric, co-planar, triply differential cross section. In the case of hydrogen, the near-threshold behavior is expected to be observable within a few eV of threshold. Using the method of exterior complex scaling we can produce accurate wave functions for electron-impact ionization of hydrogen. From these we can extract the complete ionization amplitude. To the extent that comparison is possible, our results agree well with experimental data and the predictions of semi-classical theory. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449317

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Two approaches based on the R-matrix method to study electron impact ionization at intermediate incident electron energies are discussed. These are the R-matrix with pseudo-states approach (RMPS) and the intermediate energy R-matrix method (IERM). Recent results to illustrate the key features of these methods are presented. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449318

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We briefly review recent progress in the field of electron-impact ionization of light atoms concentrating on those theories which attempt to fully solve the underlying scattering problem. Comparison between competing theories and experiment shows up some unexpected discrepancies. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449319

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

New coplanar (e,3e) and (e,3-1e) experiments on helium at about 600 eV incident energy are presented. The results are discussed in comparison with state-of-the-art first order theories and with former (e,3e) experiments at higher energy. The whole set is analyzed in terms of double ionization mechanisms. Clear evidence is given for the increasing importance of second or higher order effects in the projectile target interaction when decreasing the incident energy. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449320

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Electron impact double ionization with full determination of the kinematics of the collision, (e,3e), can, in principle, provide direct information on the correlated motion of the ejected electrons at the instant of ejection, provided that the mechanism of ejection is known. The symmetries of the observed double ionization cross sections in a variety of kinematic regimes can be used to experimentally investigate ejection mechanisms. The sensitivities of various experimental geometries and kinematic regimes to different ionization mechanisms are discussed in the context of the double ionization of the 3s electrons of magnesium. The practical implications for extracting information about electron correlation are examined. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449321

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The interaction of helium with a very intense ultrashort laser pulse (whose photon energy exceeds the double ionization potential) is studied by solving the corresponding time-dependent Schro¨dinger equation in its full dimensionality. At low intensity, our results for the total ionization yield agree very well with those obtained by using accurate one-photon total ionization rates. A momentum space analysis of the ionizing two-electron wavepacket allows us to extract qualitative but also quantitative information about various single and double ionization processes. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449322

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

In the present contribution we focus on the importance of the initial bound state wave function, and in particular on the essential role played by the electron-electron corelation, in the interpretation of several coincidence experiments on helium. Theoretical issues are briefly presented in order to illustrate that wave functions used in practical atomic calculations are far from the formal solutions, and questions are also raised with respect to the interpretation of recent transfer ionization measurements. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449323

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The correlated Kinematical Transfer Ionization channel cKTI in fast 4-body(p+He⇒H°+He2++e)processes has been used to probe the highly correlated contributions to the asymptotic part of the He ground state wave function. In this reaction one electron with controlled initial momentum (2.5 to 7.5 a.u.) in the He ground state is kinematically captured by the proton at large impact parameters. The measured 3-particle final-state momentum distributions show features of a well-structured three-particle momentum wave function. We conclude that cKTI must almost exclusively proceed via the highly correlated and, virtually excited, non-s2contributions in the He ground state. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449324

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

We compare experimental triply differential cross sections for single ionization of He for small (100 MeV/amuC6+projectiles) and large perturbation (3.6 MeV/amuAu53+projectiles). For electrons emitted into the scattering plane at the small perturbation, the data are well described by our calculations. For the large perturbation as well as outside the scattering plane for the small perturbation, in contrast, serious discrepancies especially with the continuum distorted wave-eikonal initial state (CDW-EIS) model are found. ©2002 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1449325

出版商:AIP    

年代:1902

数据来源: AIP