Metal-neon compound ions in slow field evaporation
Abstract
A magnetic sector atom-probe has been employed to study slow field evaporation of most of the transition metals in vacuum, in neon and in a mixture of neon and hydrogen. Various metals were found to form metal-neon molecular ions. Slow field evaporation and the presence of hydrogen are favorable for their formation. All the experiments were done at 78 K. The metals that evaporate as nei'des abundantly are Ti, Zn, Zr, Nb, Mo, Pd and Ta, of which Ti, Nb and Pd produce neïde ions as much as 80 to 90%. There were also some neïdes with W, Re, Ir and Rh, definitely above the detection limit estimated to be 3% of the field evaporating metal ions. The role of hydrogen is thought to be two-fold: At the surface, hydrogen adsorption is assumed to cause a stronger metal-neon bond, while the electron shower from free space ionization of the auxiliary gas excites or ionizes the complex by electron impact to allow evaporation at a reduced field.
- Publication:
-
Surface Science
- Pub Date:
- February 1977
- DOI:
- 10.1016/0039-6028(77)90104-2
- Bibcode:
- 1977SurSc..62..610K