Two-dimensional imaging of metastable CO molecules

Direct time and spatially resolved detection of metastable CO molecules, prepared in selected quantum states via pulsed laser excitation, is experimentally demonstrated in a molecular beam machine. Characterization of the molecular beam in terms of parallel and perpendicular velocity distributions and rotational temperatures is performed. A direct two-dimensional (2D) demonstration of the mass-focusing effect in binary gas mixtures is given. Two-dimensional imaging of the spatial distribution of the metastable a 3Π CO molecules in the beam after passage through a hexapole field is used to study hexapole focusing performance. Structured 2D images demonstrate the dependence of the focusing characteristics on the magnitude of the Λ-doubling and on the angular dependence of the focusing force in a hexapole consisting of cylindrical rods.