The formation of Na + and Na + 2 ions from Na*( 2 P ) atoms near a tungsten surface. II. Extended diatomics‐in‐molecules models

Potential energy surfaces ( PES ) for Na( 2 S , 2 P ) interacting with a tungsten surface partially covered with sodium ions are computed within the framework of the diatomics‐in‐molecules (DIM) method. A small number (1 to 10) of adsorbed sodium atoms are considered explicitly, the effect of the rest being taken into account through the fragment matrix elements in the DIM formulation. A physical model proposed previously to account for the experimental observation of Na + and Na   + 2ions is supported by these calculations and, in addition, a new pathway to Na   + 2products is identified. The effect of including extra adsorbed atoms is discussed in terms of the molecular wave functions and a sensitivity analysis.