Resonant charge transfer at dielectric surfaces Electron capture and release due to impacting metastable nitrogen molecules

• Published in: The European physical journal. D, Atomic, molecular, and optical physics Vol. 66; no. 4
• Main Authors: Marbach, J., Bronold, F. X., Fehske, H.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-04-2012; EDP Sciences
• Subjects: Applications of Nonlinear Dynamics and Chaos Theory; Atomic; Atomic and molecular collision processes and interactions; Atomic and molecular physics; Exact sciences and technology; Interactions of atoms, molecules and their ions with surfaces; photon and electron emission; neutralization of ions; Molecular; Optical and Plasma Physics; Physical Chemistry; Physics; Physics and Astronomy; Quantum Information Technology; Quantum Physics; Regular Article; Scattering of atoms, molecules and ions; Spectroscopy/Spectrometry; Spintronics; Plasma Physics; Inorganic compounds; Dielectric materials; Diamonds; Molecule-surface impact; Binary compounds; Shape resonance; Diatomic molecules; Secondary electron emission; Silica; Green function; Electron capture; Aluminium Oxides; Negative ions; Nitrogen Molecules; Rate equation; Silicon Oxides; Kinetic energy; Charge transfer; Alumina; Magnesium Oxides
• ISSN: 1434-6060; 1434-6079
• DOI: 10.1140/epjd/e2012-30014-8

We report on the theoretical description of secondary electron emission due to resonant charge transfer occurring during the collision of metastable N
2
(
3
Σ
+
u
) molecules with dielectric surfaces. The emission is described as a two step process consisting of electron capture to form an intermediate shape resonance N
2
-
(
2
Π
g
) and subsequent electron emission by decay of this ion, either due to its natural life time or its interaction with the surface. The electron capture is modeled using the Keldysh Green’s function technique and the negative ion decay is described by a combination of the Keldysh technique and a rate equation approach. We find the resonant capture of electrons to be very efficient and the natural decay to be clearly dominating over the surface-induced decay. Secondary electron emission coefficients are calculated for Al
2
O
3
, MgO, SiO
2
, and diamond at several kinetic energies of the projectile. With the exception of MgO the coefficients turn out to be of the order of 10
-1
over the whole range of kinetic energies. This rather large value is a direct consequence of the shape resonance acting as a relay state for electron emission.