Role of static and dynamic polarization in Photoionization of Endohedrals

  Miron Ya Amusia  ,  Miron Ya. Amusia [1, 2]  ,  Larissa V. Chernysheva [2]  
[1] The Racah Institute of Physics, the Hebrew University, Jerusalem 91904, Israel
[2] A. F. Ioffe Physical-Technical Institute, St. Petersburg 194021, Russian Federation

We have calculated photoionization cross section of endohedral atoms A@CN. For the first time, we took into account simultaneously the polarizability of the fullerene electron shell CN that modifies the incoming photon beam and the modification of the one-electron wave functions of the caged atom A under the action of CN and atom A polarization potentials. The properly modified one-electron wave functions became a starting point of the account of the multi-electron correlations in the frame of the random phase approximation with exchange (RPAE). As concrete objects, we have considered Ar and Xe atoms inside fullerene C60. We demonstrate that the effect of polarizability of the fullerenes CN electron shell strongly affects the caged atom A photoionization cross section due to dynamic CN polarization, i.e. via the modification of the incoming photon beam that acts upon atom A, located inside CN, as a resonator or amplifier. To study this effect qualitatively, we assume the validity of a strong inequality rA<R and UF = -αc/2(r2+R2)2 for r>R. Along with СN polarization, we took into account in a similar approximation the polarization potential of the atom A itself. In the calculations performed we described the fullerenes shell by a Lorentz-shape potential that represents the charge density distribution in CN qualitatively better than previously used by most researchers square well potential. The results obtained demonstrate profound influence of static and dynamic polarizabilities at low photon energies. Obviously, the influence of the fullerenes shell dies out, as it should be, with photon energy growth.