New structure in the energy distribution of H+ produced by Field ionization of HD is reported. The structure is shoti to result from a field induced pendulum type of motion of HD+ before it dissociates. Effects of associated pair field ionization are discussed.
Measurement of the energy distribution of ions produced by field ionization near a surface has contributed to an understanding of the phenomena invalved. Jason et al. [l] , Jason [2] and Mueller and ; . . % + from H&g, . . Krishnaswarny [3] have shown that the energy distribution of parent ions, e.g., Hz, CO+, He*, Ne+, _ . F=2.1 "q .and Af, exhibits a series of peaks simiIar to that 36 OV Full Scala shown in fig. 1. It was suggested by Jason et aI. [I ] ;r . . co . that this structure could be explained in terms of z -. electron tunnelling into field induced resonance 5 -. states, alternatively termed, resonance tunneIIing_ 4 -s . This idea was developed and studied in detail by Jason [2]. Lucas re-evaluated the experimental data, concluding that it was not fully in agreement with the predictions of resonance tunnelling. He suggested an alternative explanation, i.e., that the structure is L . the result of energy losses due to surface plasmon -ENERGY DEFICIT (5eV per Division) _.