摘要:

Molecules exposed to intense, sub-picosecond laser fields exhibit phenomena such as above threshold ionization, high harmonic generation, bond softening, bond hardening (vibrational trapping) and alignment. They can be deflected, accelerated, focused, trapped and spun. More generally, one can manipulate the outcome of a uni-or bimolecular reaction by the coherent superposition of two or more lasers (coherent control) or by using a sequence of ultrashort laser pulses. This article will take a brief and necessarily limited look at some of these methods of molecular manipulation. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302638

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Bose-Einstein condensed atomic gases are a new class of quantum fluids. They are produced by cooling a dilute atomic gas to nanokelvin temperatures using laser and evaporative cooling techniques. In this paper we review developments in Bose-Einstein condensation, emphasizing how this new quantum fluid has become a laboratory for the study of collisions at ultralow energy and of collective effects in light-atom and atom-atom interactions. Magnetic fields have been used to modify the scattering length for atomic collisions. Spinor condensates were created, with a spin structure determined by spin relaxation collisions and external magnetic fields. We have used light scattering to study collective excitations and observed superradiant light emission. Dissipation was studied by dragging a repulsive, blue-detuned laser beam through the fluid, as well as by inducing collisions between condensates. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302639

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The application of ion storage rings to the study of electron-molecular ion interaction has led to an experimental breakthrough. The development since the first experiments with molecular ions in storage rings about seven years ago, which in themselves represented a big leap forward, has been striking, and was impossible to envision at the outset. The development has been driven by advances in accelerator physics, detector technology, challenging applications in astrophysics and atmospheric physics, and by a close interplay with theory. Despite the remarkable progress, many important questions remain unanswered. For example, even for someone with a good knowledge of molecular physics it may come as a surprise that it is far from understood how the simplest polyatomic moleculeH3+recombines with electrons, and it remains an experimental controversy at what rate it recombines. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302640

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Dynamic processes induced by the high potential energy of multiply charged ions have been investigated in a large number of collision systems during the last years. We give a review of these activities with special emphasis on the developments since the last ICPEAC in Vienna 1997. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302641

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

This short survey is devoted to some achievements in theoretical study of negative ion photodetachment over recent years. The results of photodetachment cross section calculations performed within various theoretical approaches are discussed. Main attention is centered on the resonances in the single-electron photodetachment where the manifestation of many-electron effects is essential. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302642

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Exact numerical solutions of the time dependent Schroedinger equation, TDSE, of one and two electron molecules and ions allow us to investigate the highly nonlinear, nonperturbative behavior of such systems in the presence of ultrashort(t<50 femtoseconds),intense(I⩾1014&hthinsp;W/cm2)laser pulses. Quasistatic models of ionization lead to a qualitative understanding of a universal phenomenon occurring in these extreme conditions: Charge Resonance Enhanced Ionization, CREI. Exact non-Born Oppenheimer TDSE simulations of the dissociative-ionization ofH2+lead to the conclusion that CREI is responsible for anomalous kinetic energy distributions observed in Coulomb Explosion experiments, i.e., Coulomb explosions are non-Franck-Condon and occur at critical internuclear distancesRcand geometries. Analytic formulas are obtained forRcwhich are shown to arise from charge resonance or transfer induced at the maximum field strength of the laser fields. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302643

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The possibility to form doubly excited states give rise to resonances in photodetachment spectra. The states are fragile, dominated by electron correlation and require a careful theoretical treatment. Here recent calculations onHe−andLi−are discussed and the resonances are compared to those in the well studiedH−-ion. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302644

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The angular distribution and spin polarization of the XeN4,5O2,3O2,3Auger electrons was measured with linearly and circularly polarized synchrotron radiation in a wide photon energy range, covering the Cooper minimum of the4dphotoionization cross section. Using the framework of the two-step model of Auger decay the photoion alignment and orientation were determined. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302645

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Angular correlation patterns ofN5-O23O231S0Auger electrons in coincidence with4d5/2photoelectrons in two-step double photoionization of xenon and those of two emitted photoelectrons in coincidence with each other in direct double photoionization of helium have been studied with elliptically polarized photons. Circular dichroism in the angular distribution patterns has been reported in both cases. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302646

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

This report highlights the progress on photodouble ionization ofH2/D2using coincidence techniques and synchrotron radiation. The results will be compared to recent theoretical studies, whose methods are also outlined, and with corresponding measurements in helium. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1302647

出版商:AIP    

年代:1900

数据来源: AIP