Experimental determination of the dipole moment of HCl dimer using an electrostatic hexapole field

HCl dimers were prepared in a pulsed supersonic beam of neat HCl. The dimers were focused in an electrostatic hexapole field. Using computer simulation, the focusing curve could be fit, assuming contributions from both first and second order Stark effects. The dipole moment, based on simulation, was found to be 1.5 +/- 0.1 D. The ability to observe an effective dipole moment in a system where the donor-acceptor tunneling is fast is surprising. It may indicate that the understanding of the interaction of floppy systems with hexapole field is not complete.