Rotational-state-resolved collisional attenuation of hexapole focused hydroxyl radical beams by gas-phase target molecules

Hydroxyl radicals from a supersonic discharge source were rotationally state-selected by a hexapole. Two |J Ω M〉 states were resolved, the |32 32 32〉 and |32 32 12〉 states. Scattering gases (He, Ar, H2O, CO2 NH3, and CH3F) were admitted to the hexapole chamber attenuating the hydroxyl radical beam. Analysis of the attenuation as a function of gas pressure yielded the relative scattering cross-sections. Simulations of the focusing spectra suggest that elastic scattering rather than M changing collisions dominate the scattering. No differences in the scattering cross-sections for the |32 32 32〉 and |32 32 12〉 states were observable.