Measurement of pick-up cross-sections of 4He clusters: polar versus non-polar molecules

Pick-up cross-sections of free large 4He clusters formed in free jet expansions have been measured to determine the influence of the molecular properties of target molecules in the capture process. The pick-up cross-section depends strongly on the dipole moment of the molecule. For non-polar molecules, earlier measurements of pick-up cross-sections ranging from 2000 to 4300 Å2 were ponfirmed; for polar systems, however, cross-sections between 6400 and 8100 Å2 were observed. In both cases a linear cross-section versus mass dependence is observed.