Generation of intense, hexapole-selected, supersonic beams of fluorocarbon radicals: CF, CF2, and CF3

Intense molecular beams of fluorocarbon radicals were generated with a corona discharge passing through a supersonic jet expansion of 15% C2F6 in Ar. An electrostatic hexapole separated the polar neutrals entrained in the beam by selectively focusing them through a small aperture. Molecules were separated according to the ratio of their mass to permanent electric dipole moment (m/mu) and according to their rotational state. Our most dramatic success was in isolating CF radicals in a single rotational state: \J Omega M-J)=\1/21/21/2]. The pure, state-selected CF radical beam was characterized by a narrow velocity distribution (Delta upsilon/upsilon similar to 14%) and high flux density (J=8 x 10(11) radicals cm(-2) s(-1)). Adjustments in the hexapole voltage and discharge conditions produced variations in the beam composition of 100% CF, 0% CF2, 0% CF3 to 20% CF, 0% CF2, 80% CF3, and 60% CF, 15 CF2, 25% CF3 with no other detectable components (e.g., F and C atoms, C2F6). (C) 1997 American Vacuum Society.