# Nondipole Effects in Double Photoionization of He

## Abstract

Lowest-order nondipole effects are studied in double photoionization (DPI) of the He atom. Ab initio parametrizations of the quadrupole transition amplitude for DPI from the 1S0-state are presented in terms of the exact two-electron reduced matrix elements. Parametrizations for the dipole-quadrupole triply differential cross section (TDCS) and doubly differential cross section (DDCS) are presented in terms of polarization-independent amplitudes for the case of an elliptically polarized photon. Expressions for the DDCS in terms of the reduced two-electron matrix elements are also given. A general analysis of retardation-induced asymmetries of the TDCS including the circular dichroism effect at equal energy sharing is presented. Our numerical results exhibit a nondipole forward-backward asymmetry in the TDCS for DPI of He at an excess energy of 450 eV that is in qualitative agreement with existing experimental data.

- Authors:

- Department of Physics and Astronomy, University of Nebraska, Lincoln, NE 68588-0111 (United States)
- Physics Department, Voronezh State University, Voronezh 394006 (Russian Federation)

- Publication Date:

- OSTI Identifier:
- 20797872

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: AIP Conference Proceedings; Journal Volume: 811; Journal Issue: 1; Conference: International symposium on (e,2e) double photoionization, and related topics; 13. international symposium on polarization and correlation in electronic and atomic collisions, Buenos Aires (Argentina), 28-30 Jul 2005; Other Information: DOI: 10.1063/1.2165614; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 74 ATOMIC AND MOLECULAR PHYSICS; ASYMMETRY; DICHROISM; DIFFERENTIAL CROSS SECTIONS; DIPOLES; ELECTRONS; ENERGY LEVELS; EV RANGE; HELIUM; MATRIX ELEMENTS; PHOTOIONIZATION; PHOTONS; POLARIZATION; QUADRUPOLES; TRANSITION AMPLITUDES

### Citation Formats

```
Istomin, A. Y., Starace, A. F., Manakov, N. L., and Meremianin, A. V.
```*Nondipole Effects in Double Photoionization of He*. United States: N. p., 2006.
Web. doi:10.1063/1.2165614.

```
Istomin, A. Y., Starace, A. F., Manakov, N. L., & Meremianin, A. V.
```*Nondipole Effects in Double Photoionization of He*. United States. doi:10.1063/1.2165614.

```
Istomin, A. Y., Starace, A. F., Manakov, N. L., and Meremianin, A. V. Mon .
"Nondipole Effects in Double Photoionization of He". United States.
doi:10.1063/1.2165614.
```

```
@article{osti_20797872,
```

title = {Nondipole Effects in Double Photoionization of He},

author = {Istomin, A. Y. and Starace, A. F. and Manakov, N. L. and Meremianin, A. V.},

abstractNote = {Lowest-order nondipole effects are studied in double photoionization (DPI) of the He atom. Ab initio parametrizations of the quadrupole transition amplitude for DPI from the 1S0-state are presented in terms of the exact two-electron reduced matrix elements. Parametrizations for the dipole-quadrupole triply differential cross section (TDCS) and doubly differential cross section (DDCS) are presented in terms of polarization-independent amplitudes for the case of an elliptically polarized photon. Expressions for the DDCS in terms of the reduced two-electron matrix elements are also given. A general analysis of retardation-induced asymmetries of the TDCS including the circular dichroism effect at equal energy sharing is presented. Our numerical results exhibit a nondipole forward-backward asymmetry in the TDCS for DPI of He at an excess energy of 450 eV that is in qualitative agreement with existing experimental data.},

doi = {10.1063/1.2165614},

journal = {AIP Conference Proceedings},

number = 1,

volume = 811,

place = {United States},

year = {Mon Jan 09 00:00:00 EST 2006},

month = {Mon Jan 09 00:00:00 EST 2006}

}