Molecular Beam Collisions with a Magnetically Trapped Target

Cold, neutral hydroxyl radicals are Stark decelerated and efficiently loaded into a permanent magnetic trap. The OH molecules are trapped in the rovibrational ground state at a density of similar to 10(6) cm(-3) and temperature of 70 mK. Collision studies between the trapped OH sample and supersonic beams of atomic He and molecular D(2) determine absolute collision cross sections. The He-OH and D(2)-OH center-of-mass collision energies are tuned from 60 cm(-1) to 230 cm(-1) and 145 cm(-1) to 510 cm(-1), respectively, yielding evidence of quantum threshold scattering and resonant energy transfer between colliding particles.