Ion beam source for soft-landing deposition

“Soft-landing” deposition of molecular ions on various surfaces is important in making exotic radicals, modeling electrochemical double layers, and studying aqueous ion interactions. We have built a new mass-selected ion beam source for soft-landing deposition, designed to produce either positive or negative ions, including ions that depend on ion-neutral reactions (e.g., H3O+ and NH4+). The ionizer is a free jet crossed by an electron beam, producing a wide variety of positive and negative ions. The simple, short-length, planar ion deceleration minimizes defocusing and space charge effects. It currently delivers mass-selected ions with energies down to about 1 eV and currents of about 10 nA. The design allows easy maintenance. The performance of the ion beam compares favorably with previous low-energy positive ion systems.