摘要:

Results of studies of ion rotational and vibrational distributions for resonance enhanced multiphoton ionization are discussed.(AIP)

ISSN:0094-243X    

DOI:10.1063/1.39176

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Triatomic hydrogen in the lowest rotational level of the 2p2A2‘state is long‐lived (∼80 &mgr;s). This molecule is readily formed in charge transfer of H+3in cesium. Laser excitation of the molecule allows study of electric field induced ionization as well as autoionization of the Rydberg series of H3. Two photon ionization and double resonance techniques are applied to determine vibrational frequencies of trihydrogen.Experimental analysis of the electron‐core interaction shows that selective optical excitation of core rotation and core vibration can be achieved concurrent with excitation of the Rydberg electron. Predissociation of Rydberg states is observed to lead to the formation of both H2+H as well as H+H+H fragments.

ISSN:0094-243X    

DOI:10.1063/1.39178

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Recent (e, 2e) experiments concerned with behaviour at the Wannier‐ridge will be presented and discussed. The parameters of the Wannier model and the range of validity of the model are deduced from an analysis of experiments carried out in the perpendicular plane together with data on earlier coplanar experiments. Bound atomic states at the Wannier‐ridge are then considered and new results are presented. A double‐Rydberg formula is developed for Wannier‐ridge intrashell states of atoms that have a non‐nuclear core. A ‘‘double‐electron quantum defect’’ that decrease as the principal quantum number n increases is proposed. The formula is applied to the He−1sns2series.

ISSN:0094-243X    

DOI:10.1063/1.39187

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

High doubly‐excited states of atoms or high singly excited states of an atom in an external field, electric or magnetic, display a strong mixing of angular configurations. This angular correlation leads to states which are sharply localized in coordinate space. A unified description and form of the mixing in state space and the localization in real space is developed. Analytical forms for these in the shape of Gaussian functions follow for all these problems as solutions of a spheroidal differential equation.

ISSN:0094-243X    

DOI:10.1063/1.39193

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have used the interaction of hydrogen Rydberg atoms with microwave fields to study multiphoton ionization. The minimum number of photons absorbed in the experiments ranges from about 300 to only 15. A brief overview is given of the extensive theoretical work that is under development to explain experimental data, including various observed structures. Similarly we report on ionization of helium Rydberg atoms, qualitatively explained in terms of a static picture. Finally we show selective excitation of He triplets‐state to higher angular momentum states, via absorption of several photons from the field. Using the Floquet method a close analogy between the microwave problem and slow atomic collisions can be made. Sharp resonant structures in the spectra can be linked to individual avoided crossings of calculated Floquet quasi‐energy curves. Our theory that exploits a separation of timescales explains very well the positions, depths, and shapes of the observed structures, but a discrepancy still remains concerning their widths.

ISSN:0094-243X    

DOI:10.1063/1.39175

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We review the response of a hydrogen atom to a periodic electric field with a view to isolating the properties of the Coulomb potential which make this system special. We consider both 1dand 3dmodels and provide tentative predictions about the behavior of the 3dsystem in a high frequency field, based upon exact classical calculations and approximate semiclassical theory.

ISSN:0094-243X    

DOI:10.1063/1.39177

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The rate of atomic ionization is found in the long wavelength limit and high electric field limit.(AIP)

ISSN:0094-243X    

DOI:10.1063/1.39179

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The dynamics of relativistic plasmas created by intense short‐pulsed lasers is illustrated using analytic solutions for unconstrained electrons and numerical simulations of space–charge effects. These models provide a basis for the analysis of laser‐induced nuclear reactions, recombination lasers and wakefield accelerators.

ISSN:0094-243X    

DOI:10.1063/1.39180

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Although there has been substantial progress in theab initiotreatment of low energy electron scattering from small diatomic and polyatomic molecules in the last few years a number of problems still remain. Most current research has focused on the calculation of fixed nuclei scattering amplitudes in the static–exchange (SE) approximation. A few calculations have gone beyond this approximation to include electron correlation and/or vibrational and rotational effects, the latter often within the framework of model or parameterized potentials.In this article we review a number of developments which have occurred since the last electron molecule satellite meeting at Daresbury Laboratory in July 1987. Our primary objective shall be to point out the strengths and weaknesses of current computational capabilities and to describe a new approach to electron polyatomic collisions using the complex Kohn method.

ISSN:0094-243X    

DOI:10.1063/1.39181

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

New methods which use Classical Mechanics are employed to compute line widths of chaotic spectra. The equivalence of a specified very general type of intramolecular vibrational relaxation (IVR) spectra to chaotic spectra is used to present a new theory of IVR rates. Computed widths for real systems are in good agreement with experiment.

ISSN:0094-243X    

DOI:10.1063/1.39182

出版商:AIP    

年代:1990

数据来源: AIP