How to study the elusive efimov state of the 4He3 molecule through a new atom-optical state-selection technique

Atom symmetry break and metastable level coupling in rare gas atom-surface van der Waals interaction

van der Waals interactions between an atom and a planar surface exhibit a quadrupolar component in D(2)(z)-D(2)/3 (D, atomic dipole; ź, normal to surface). This coupling is responsible for an atom symmetry break, mixing levels of the same parity such as metastable 3P0, 3P2 levels of rare gas atoms. The strongly exoenergic 3P0-3P2 transition in Ar and Kr is observed by a time-of-flight technique, using as a surface the edge of a copper slit. The results confirm the predicted strong peaking of the angular distribution of inelastically scattered atoms and give a good estimate of the transition probability.

Determination of the bond length and binding energy of the helium dimer by diffraction from a transmission grating

A molecular beam consisting of small helium clusters is diffracted from a 100 nm period transmission grating. The relative dimer intensities have been measured out to the 7th order and are used to determine the reduction of the effective slit width resulting from the finite size of the dimer. From a theoretical analysis of the data which also takes into account the van der Waals interaction with the grating bars, the bond length (mean internuclear distance) and the binding energy are found to be <r> = 52+/-4 A and |E(b)| = 1. 1+0.3/-0.2 mK.