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The first fully on-line isotope shift measurement of a radioactive refractory element is reported. Collinear laser-induced fluorescence measurements were made on the radioactive isotopes 170,172,173,174 Hf produced with a flux of 2 3 3 10 3 ions per second from an ion-guide fed isotope separator. The method may be applied to all elements and isomers with lifetimes as short as 1 ms. The systematics of the new charge radii measurements are well reproduced by theory, with the maximum deformation in the chain occurring significantly below the midshell. [S0031-9007(99)

We introduce a new technique, extended spectral analysis of multiple beam interferometry (ESA-MBI), which significantly expands the variety of surfaces that can be investigated in the surface forces apparatus (SFA). The underlying principle of the technique is to capture the intensity versus wavelength profile of light transmitted through the surfaces; the distance between them is then determined by matching the measured spectra with that predicted from the theory of wave propagation through a stratified medium. ESA-MBI requires two key ingredients: (1) a camera system capable of measuring the intensity versus wavelength spectra and (2) the implementation of theory to preduct it. We describe these two ingredients and show how ESA-MBI can be used in conjunction with the SFA to investigate the interactions between two opposed surfaces where one, or both of the surfaces is metallic. Finally, we describe a procedure wherein ESA-MBI is employed to measure the refractive indices of thin metal films, and we report our results for thermally evaporated silver and gold. This procedure is necessary to maximize the accuracy of surface separation measurements.

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