The translational energy distributions for metal atoms and ions produced via visible laser MPD/MPI of group 13 metal alkyls and MPI of aluminum and indium atomic beams

Abstract

The nascent translational energy distributions of group 13 metal ions produced via multiphoton dissociation and multiphoton ionization (MPD/MPI) of their trimethyl derivatives and via multiphoton ionization of metal atomic beams have been measured using time-of-flight mass-spectroscopy. In all cases the ion production was isotropic and the translational energy distribution was approximately Boltzmann. For ionization of free aluminum and indium atoms translational temperatures of 6K and 4K were measured, corresponding to most probable velocities of 60 and 24 ms⁻¹. From multiphoton dissociation of trimethylaluminum, trimethylgallium, and trimethylindium, translational temperatures of 1800, 700, and 900 K resulted. These correspond to velocities of ∼1000, 400, and 350 ms⁻¹. A photodissociation mechanism involving elimination of ethane followed by dissociation of monomethyl metal intermediates to produce metal atoms is in reasonable agreement with the experimental data. The nascent velocities of metal atoms and ions from the metal alkyl and metal beam sources are used to assess the potential of these sources for microfabrication of metal structures.