Naslov
Separation of perturbative and nonperturbative correlation effects in He double and single ionization by absorption of a photon

Autori
Surić, Tihomir ; Pratt, R.H.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts, International Symposium on (e, 2e), Double Photoionization and Related Topics / - Frankfurt : Satellite Meetings to the XXIII ICPEAX, 2003

Skup
12th International Symposium on Polarization and Correlation in Electronc and Atomic Collisions

Mjesto i datum
Königstein, Njemačka, 30.07.2003. - 02.08.2003

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
correlation effects; photoeffect; double ionization

Sažetak
In the study of electron correlations, which is a central problem in atomic physics, investigation of single and multiple ionization of complex systems by absorption of a single photon plays an important role. This is because the photon interacts with only one electron and the dynamics of the processes is governed by the correlations between the particles of the system. At low photon energies the correlation effects generally require nonperturbative treatment. However, with increasing energies important aspects of correlations become perturbative. When the perturbative effects can be identified and evaluated, the processes can provide more explicit information about the effects for which a nonperturbative treatment is needed. We study here nonretarded single and double ionization of He at photon energies omega gg E_B E_B is the ionization energy for the process), for which final state correlations are perturbative. By using the asymptotic Fourier transform approach we identify analytically the initial state correlations (ISC) and final state correlations (FSC) which contribute to the m alpha^2/omega corrections to the leading shake results for high energy total cross sections: sigma_n^+ for single ionization with excitation to a shell $n$, and sigma^++ for double ionization. All perturbative effects in this order are evaluated. The nonperturbative results are expressed in terms of large distance ISC effects, without making any approximation for the initial state. In the high energy limit our results converge to the well known shake results (Fig. 1). Due to the dynamics of the processes at these energies, the correlation effects involve predominantly the region in which one electron is in the vicinity of the nucleus (where the photoabsorption occurs) while the other is at larger distances. Such dynamics also characterizes the single photon ionization processes of more complex atoms and molecules, which makes the approach and the identified correlation effects of more general applicability.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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