Electrostatic hexapole state selector: Honeycomb field for integrating intensity of oriented molecular beams

A type of electrostatic state selector that consists of seven sets of adjacent hexapole fields forming a honeycomb field has been developed in order to integrate intensities of seven oriented molecular beam lines. The cross section of the electric field is gradually diminished from the inlet to the outlet in order to sum up the seven molecular beam lines and focus on a focal point located 1000 mm downstream from the honeycomb field outlet. We first used nonfocusable noble gases: Ar and Kr to check the assembly alignment, and then we used the polar molecule of acetonitrile ( CH 3 CN , μ=3.92 D) seeded in the noble gases to characterize the quantum state selectivity of the honeycomb field. We obtained the dependence of the focused CH 3 CN beam intensity on the honeycomb electrode voltages. We could reproduce the experimental focusing curve by use of a modified trajectory simulation applicable to the honeycomb electric field. The present beam character (i.e., rotational temperature and stream velocity) was confirmed to be maintained.