RADIATIVE ELECTRON-ATTACHMENT IN SODIUM CLUSTERS

The electron attachment to bound unoccupied levels of spherical neutra l Na,, clusters (n = 8, 20, and 40) is analyzed using electron-cluster collisions. In the direct process here studied the captured electron loses its energy in a single step via the emission of a photon. The ai m of the present paper is to estimate the strength of this inverse pho toemission (IP) mechanism, and its contribution to the total inclusive inelastic cross section recently measured. We perform a quantum-theor etical calculation for incoming electrons in the range 0-2 eV. The mag nitudes of the total LP cross sections are dominated by transitions to the less bound unoccupied levels while their patterns depend mainly o n quasibound states in the incoming channel. It is found that in the r ange of incoming energies here analyzed the IP process has a negligibl e contribution to the inelastic inclusive experimental data. [S1050-29 47(98)00110-3].