Eur. Phys. J. D (2012) 66: 189
https://doi.org/10.1140/epjd/e2012-30081-9

Regular Article

Valence photoionization of small alkaline earth atoms endohedrally confined in C₆₀

¹ Department of Physics and Astronomy, Georgia State University, Atlanta, 30303 Georgia, USA
² Center for Innovation and Entrepreneurship, Department of Chemistry and Physics, Northwest Missouri State University, Maryville, 64468 Missouri, USA
³ Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany

^a e-mail: himadri@nwmissouri.edu

Received: 31 January 2012
Received in final form: 23 March 2012
Published online: 20 July 2012

Abstract

A theoretical study of photoionization from the outermost orbitals of Be, Mg and Ca atoms endohedrally confined in C₆₀ is reported. The fullerene ion core, comprised of sixty C⁴⁺, is smudged into a continuous jellium charge distribution, while the delocalized cloud of carbon valence electrons plus the encaged atom are treated in the time-dependent local density approximation (TDLDA). Systematic evolution of the mixing of outer atomic level with states of the C₆₀ valence band is found along the sequence. This is found to influence the plasmonic enhancement of atomic photoionization at low energies and the geometry-revealing confinement oscillations at high energies in significantly different ways: (a) the extent of enhancement is mainly determined by the strength of atomic ionization, giving the strongest enhancement for Be even though Ca suffers the largest mixing. But (b) strongest collateral oscillations are uncovered for Ca, since, relative to Be and Mg, the mixing causes the highest photoelectron production at confining boundaries of Ca. The study paints the first comparative picture of the atomic valence photospectra for alkaline earth metallofullerenes in a dynamical many-electron framework.