Based on a semiempirical generalized Anderson-Newns model, we construct a pseudoparticle description for electron emission due to deexcitation of metastable molecules at surfaces. The pseudoparticle approach allows us to treat resonant charge-transfer and Auger processes on an equal footing, as it is necessary when both channels are open. This is, for instance, the case when a metastable ${\mathrm{N}}_2{(}^3{\Sigma }_u^{+})$ molecule hits a diamond surface. Using nonequilibrium Green functions and physically motivated approximations to the self-energies of the Dyson equations, we derive a system of rate equations for the probabilities with which the metastable ${\mathrm{N}}_2{(}^3{\Sigma }_u^{+})$ molecule, the molecular ground state ${\mathrm{N}}_2{(}^1{\Sigma }_g^{+})$, and the negative ion ${\mathrm{N}}_2^{-}{(}^2{\Pi }_g)$ can be found in the course of the scattering event. From the rate equations, we also obtain the spectrum of the emitted electron and the secondary electron emission coefficient. Our numerical results indicate the resonant tunneling process undermining the source of the Auger channel, which therefore contributes only a few percent to the secondary electron emission.

• Received 29 June 2012

DOI:https://doi.org/10.1103/PhysRevB.86.115417