摘要:

Experimental studies of the production and transport of projectile excited states in solid carbon targets have been performed forAr17+andKr35+at high velocity (respectivelyvp=23and 35.6 a.u.). A range of target thickness from single collision condition to equilibrium has been investigated. Charge state distributions,nlpopulations of core and Rydberg projectile states, as well as the population of fine structure substates(nlj)are determined. Theoretical predictions have been developed both in a collisional and a dynamical screening picture, using quantum as well as classical descriptions for the transport of projectile excited states. Discussions based on a comparison between experimental results and the different types of calculations are presented. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302696

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Molecular shape as probed by a test atom from H to Ar has been studied by quantum chemical calculations, and anisotropy effects on collisional ionization dynamics have been disclosed on the basis of two-dimensional Penning ionization electron spectroscopy and trajectory calculations. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302697

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The electron spectroscopy based on the excitation energy of metastable rare gas atoms is a valuable tool for surface analysis because its surface sensitivity does not depend on the limited mean free path of the emitted electrons in condensed matter, but is perfect due to the physics of the emission process. Up to recently, the application of the method has suffered from the fact that a quantitative evaluation of the measured spectra has not been possible. The present contribution describes some progress in this respect which has been made during the last few years. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302698

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Doubly charged helium cluster ionsKr2+-Hen(n⩽40)have been produced whenKr2+ions are injected into helium gas cooled by liquid helium. Magic numbersn=12and 32 have been observed in the size distribution of these cluster ions. These magic numbers suggest the shell structure in which an icosahedron consisting of twelve helium atoms performs as a core in the cluster ion. Not only the clustering, charge transfer betweenKr2+and He also takes place as a competitive reaction of the cluster formation. Behavior of each electronic states of the incident ions in collisions with helium have been discussed on a crude potential crossing model. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302699

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The charge transfer process between a laser-cooled magnesium ion and a thermal barium atom in a radio-frequency ion trap in extremely low energy regime is observed. The merit of using the trap is that the generated ions are also confined in the trap. The occurrence of the charge transfer process is confirmed by the detection of the laser-induced fluorescence from the generated ions. The cross section of the process is estimated to be10−3&hthinsp;Å2∼10−1&hthinsp;Å2.©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302700

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Electrons ejected in the forward direction from fully-stripped and one-electron 33-TeV Pb ions passing through thin foils of Al and Au have been studied. Spectral peaks centered at a momentum equivalent to the velocity of the projectile have been measured, which are attributed to electron loss to the projectile continuum (ELC). From previous theoretical studies, the ELC ‘cusp’ shape is expected to reflect the initial state of the electron released from the projectile. The ELC peaks are very narrow even for loss from ground-state incident ions. The observed widths arise primarily from instrumental broadening effects-especially multiple Coulomb scattering (MCS). Correction of the measured electron momentum distributions for instrumental broadening leads to very narrow ELC cusps, which have essentially the same widths for loss from incident one-electron ground-state ions and loss from hydrogenic ions populated by electron capture from pair production (ECPP), where there should be significant excited-state formation. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302701

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The absolute cross section of associative ionization in the collision ofC+withD−has been measured in a merged beam experiment for collision energies ranging from 0.01 to 2 eV. The measured cross section is found to be compatible with anE−1law at low energies and presents a relative maximum between 0.8 and 1 eV. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302702

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Atom-cluster collisions are studied by means of a simultaneous and self-consistent treatment of electronic and atomic degrees of freedom involved. We examine the excitation mechanisms (electronic versus vibrational) and the related relaxation phenomena (phase transitions, fragmentation) for impact energies fromeV→MeV.“Cluster transparency” is found in a small window of energies. In addition, the laser-enhanced charge transfer competing with fragmentation in collisions with sodium clusters is investigated. A strong temperature dependence is observed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302703

出版商:AIP    

年代:1900

数据来源: AIP