THE USE OF A REFINED BEAM VELOCITY DISTRIBUTION IN THE DETERMINATION OF THE NUCLEAR ELECTRIC QUADRUPOLE MOMENT OF ${^{6}}Li$ IN THE HYPERFINE SPECTRUM OF ${^{6}}LiF$

Abstract

We have used a molecular beam spectrometer to examine the hyperfine spectrum of an isotopically concentrated sample of ${^{6}}LiF$ for the purpose of determining a more accurate value of the nuclear quadrupole moment of the ${^{6}}Li$ nucleus. This nucleus has the smallest known quadrupole moment, so that the spectral lines are not all resolved, even with our linewidths of approximately 100 Hz. In order to deconvolute these overlapping lines we needed an accurate lineshape function, which in turn required an improved distribution of the velocities selected by the electrostatic lenses. A geometric representation of the trajectories of the molecules in the transverse phase space has given this improved velocity distribution.