Naslov
Characterization of high-energy photoionization in terms of the singularities of the atomic potential. II. Beyond K-shell ionization in a many-electron atom, using the example of a two-electron atom in an excited state

Autori
Surić, Tihomir ; Drukarev, E. G. ; Pratt, R. H.

Izvornik
Physical Review A (1050-2947) 67 (2003), 2;

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
photoabsorption; ionization; correlation; many electron atom

Sažetak
We describe single photoionization of excited states of two-electron atoms by photoabsorption at high incident photon energies omega (but still omega << m). Our description of photoionization from excited states of the simplest many body system is also however applicable for the characterization of high energy photoionization of a many-electron atom from any subshell. We are using an approach [Surić {; ; ; et al.}; ; ; , Phys. Rev. A 67, 022710 (2003)]based on asymptotic Fourier transform (AFT) theory, in which the matrix elements for photoabsorption processes at high energies are understood in terms of the singularities of the many-body Coulomb potential. We obtain the dependence of the total cross section for single ionization of a two-electron atom in any initial state on photon energy. This energy dependence, for a general initial two-electron state, is generally different from the predictions of independent particle approximation (IPA), and it is in qualitative agreement with recent experimental observations of L-shell photoionization in Ne and M-shell ionization in Ar. As in ground state ionization, the energy dependence of the dominant contribution to the matrix element is connected, through AFT, with the e-N singularity and it is determined by the amplitude of the lowest angular momentum I_min with which one electron can approach the e-N singularity. When I_min=0, as in the cases considered experimentally, this gives a factor for the dominant part of the total cross section which is the same as for the ground state, (1/omega^7/2). The final state interaction reduces this energy dependence by just one additional factor of 1/omega.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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