Development and characterization of high-repetition-rate sources for supersonic beams of fluorine radicals

Abstract

We present and compare two high-pressure, high-frequency electric-discharge sources for the generation of supersonic beams of fluorine radicals. The sources are based on dielectric-barrier-discharge (DBD) and plate-discharge units attached to a pulsed solenoid valve. The corrosion-resistant discharge sources were operated with fluorine gas seeded in helium up to backing pressures as high as 30 bar. We employed a (3+1) resonance-enhanced multiphoton ionization combined with velocity-map imaging for the optimization, characterization and comparison of the fluorine beams. Additionally, universal femtosecond-laser-ionization detection was used for the characterization of the discharge sources at experimental repetition rates up to 200 Hz. Our results show that the plate discharge is more efficient in F 2 dissociation than the DBD by a factor of 8-9, whereas the DBD produces internally colder fluorine radicals.

A novel crossed-molecular-beam experiment for investigating reactions of state- and conformationally selected strong-field-seeking molecules

“…The ability of the electrostatic deflector to select different sizes of molecular clusters 59,94,95 would allow for reactions with even more complex reactants. Moreover, the discharge source developed for the present setup is also capable of producing high-density molecular beams of free radicals 76 paving the way for the investigation of state-and conformer-specific effects in reactions with these species in the present setup.…”

“…The second beam containing the reaction partner of the deflected molecular species is generated by a solenoid-based pulsed valve. 75 For the production of internally cold and dense beams of radicals or metastable rare gas atoms, this valve was combined with either a dielectric barrier discharge (DBD) or a plate discharge 76 based on the design of Ref. 77.…”

Isomeric and rotational effects in the chemi-ionisation of 1,2-dibromoethene with metastable neon atoms

“…The pulsed beam of Ne* was generated by expanding neon gas through a pulsed gas valve at room temperature with a backing pressure of 45 bar by passing through a plate electricdischarge assembly. 24 From the velocities of the molecular beams colliding at right angles, the collision energy of the reaction was calculated to be 0.36 eV.…”