Confinement resonances in photoelectron angular distributions from endohedral atoms

Abstract

Both dipole and nondipole angular distribution parameters for photoelectrons emitted from the endohedral $\mathrm{Ne}@{\mathrm{C}}_{60}$ atom are investigated within both the framework of the Dirac bubble potential model and spherical, short range potential well of finite thickness $\ensuremath{\Delta}T$. It is demonstrated, for $1s$, $2s$, and $2p$ photoelectrons of $\mathrm{Ne}$, that because the fullerene shell acts as a resonator in this process, the energy dependence of the photoelectron angular distribution parameters differ considerably from that of the free $\mathrm{Ne}$ atom. For confined $\mathrm{Ne}$, in contrast to the isolated $\mathrm{Ne}$ atom, these parameters as a function of photon energy acquire a significant resonance structure, owing to oscillations in the photoionization matrix elements induced by the fullerene shell.