A two element magneto-optical trap (MOT) for Na and Li-7 or Li-6 is used to cool and trap each of them separately. A fraction of the cold atoms is maintained in the first P-2(3/2) excited state by the cooling laser. These excited state atoms are ionized by laser light in the near-UV region, giving rise to a smaller number of trapped atoms and to different loading parameters. Photoionization cross-sections were derived out of these data. They are in reasonable agreement with data previously obtained using thermal samples and with theoretical predictions
Front Cover: The preparation of different styrene‐based polymer films containing small amounts of tetraphenylethylene (TPE) and the evaluation of their photoluminescent behavior are reported. TPE molecular rotors show brilliant blue emission in a poor solvent or in a glassy styrene‐based polymer matrix, where the intramolecular rotations of its aryls result as being completely arrested, but the fluorescence is weakened to pale green and eventually to a faint signal when good solvents or viscous but not glassy polymer matrices are used. This behavior suggests potential benefits in applications such as polymer traceability. Further details can be found in the article by G. Iasilli, A. Battisti, F. Tantussi, F. Fuso, M. Allegrini, G. Ruggeri, and A. Pucci* on page 499.
With an atomic force/friction force microscope operating in the constant force mode and with an optical lever technique as a deflection sensor, we have investigated the total force acting on the cantilever tip during the raster scanning of the sample surface. A model including the normal and lateral components of the force has been worked out. The normal force is related to the cantilever loading. The lateral force has two components, dissipative and nondissipative, having opposite symmetry with respect to the scanning direction. Within our model, the nondissipative component, which is related to the topography, can be distinguished from the friction component in two different ways, both leading to ‘‘pure friction’’ images. The first method is based on the comparison of two images acquired in the forward and backward scanning direction, respectively. The second method is based on the comparison of the topographic and lateral force images acquired in the same scanning direction. This latter way does not need correction for the nonlinear behavior of the piezoelectric transducer. Results from various samples are reported.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.