摘要:

The energy distributions of convoy electrons produced at glancing angle incidence of fast ions are studied with Classical Trajectory Monte Carlo (CTMC) calculations. The image potentials both of the ion and of the convoy electron are taken into account. For light ions, the acceleration of the convoy electron by the ion's image potential isdepressedby the image potential of the convoy electron, while for heavy ions this effect is negligible.

ISSN:1042-0150    

DOI:10.1080/10420159108220604

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Convoy electrons produced at glancing angle scattering of MeV HeH+ions from an atomically clean (001) surface of SnTe crystal are observed. Energy spectrum of the convoy electrons shows a peak broader than that at scattering of atomic projectiles and the most probable energy of convoy electrons at HeH+scattering is larger than those at scattering of isotachic He ions. This acceleration of convoy electrons is qualitatively explained by the force due to surface wake induced by Coulomb exploding fragment He2+and H+.

ISSN:1042-0150    

DOI:10.1080/10420159108220605

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Skipping motions of energetic ions at a surface are discussed as a discrete energy loss separation. We propose a new oscillatory motion of channeling ions due to the optical potential (dynamical attractive potential) near an atomic wall, which may be called as the “dynamical channeling”.

ISSN:1042-0150    

DOI:10.1080/10420159108220606

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159108220607

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We sketch developments in the theory of the self-energy of charged particles moving near condensed matter surfaces. Some applications to experimental results from spectroscopy with electrons localized in microprobe beams and to electrons tunneling across a gap between two metals are considered.

ISSN:1042-0150    

DOI:10.1080/10420159108220608

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159108220609

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We evaluate electron excitation spectra generated by slow ions in an electron gas. Energy and angular spectra, and total excitation rates, are given. Non-linear screening effects on the intruding chargeZresult inZoscillations in the spectra of electron excitations and in the total excitation rate. Predictions are given, for different electron gas densities, using phase shifts obtained from numerical self-consistent solutions of the Kohn-Sham density-functional formalism. The results are compared with those obtained in the linear dielectric response, and with the pseudopotential model of target response. The connection between electron excitation spectra and ion energy loss parameters (stopping power and straggling) is discussed.

ISSN:1042-0150    

DOI:10.1080/10420159108220610

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Stopping powers of Al, Ti, Cu, Zr, Rh, Ag, Ta and Au for 26 MeV alpha particles have been measured using a surface barrier silicon detector with an accuracy of 0.35%. The stopping powers for alpha particles divided by 4 have been compared with the stopping powers for 6.500 MeV protons of the same velocity. Experimental magnitudes of theZ31correction which is contained in the Bethe-Bloch stopping formula were extracted using the alpha-proton difference. Using the experimentalZ31corrections thus obtained and the experimentalZ31corrections of the previous paper, parameters of γ andbwhich appear in the theory of Ashley, Ritchie and Brandt for theZ31correction have been determined with exactly the same method as the previous paper as γ = 1.336 andb= 1.32. The magnitude of theZ31correction calculated by the theory of Ashley, Ritchie and Brandt using these parameters have been compared with those obtained by other authors.

ISSN:1042-0150    

DOI:10.1080/10420159108220611

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Stopping powers of metallic elements have been measured for 55, 65 and 73 MeV protons and for 13 MeV/u4He and12C ions using a high resolution magnetic spectrograph. Analyzing experimental data for protons with the Bethe-Bloch formula, we deduced mean excitation energies for 10 metallic elements. The magnitude of Barkas correction was extracted from stopping power difference for4He and12C ions at the same velocity, which was found to be consistent with those measured in previous experiments.

ISSN:1042-0150    

DOI:10.1080/10420159108220612

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Recent measurements of the stopping powers of various composite-material targets have been analyzed in the presence of Barkas-effect and Bloch corrections in order to extract appropriate values of Bethe-Bloch parameters. Mylar, Kapton, and Havar targets have been studied in particular, primarily using measurements with light projectiles. The present investigation focuses on results for Havar analyses, where dispersion among sets of measurements appears to separate extracted parameter-values into at least two groups. An hypothesis pertaining to target properties is advanced in explanation. In another study, analyses of experimental results for alpha particle projectiles traversing Ti and V targets have yielded parameter-values reasonably consistent with expectation. Finally, the importance of including all pertinent correction terms when analyzing data with Bethe-Bloch stopping power theory is emphasized.

ISSN:1042-0150    

DOI:10.1080/10420159108220613

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor