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abstract
Ultraviolet extinction curves have been derived from 3.2 to 10.8 $\mu m^{-1}$ for the stars $\zeta $ Oph, $\xi $ Per and $\sigma $ Sco, spanning the range in far-uv extinction rises for diffuse clouds. Data from the IUE and Voyager archives have been combined and extinction curves derived by the pair method using model atmospheres as non-reddened standards. Model extinction calculations for multi-component size distributions of silicate and carbonaceous materials fitted to the data are presented, and the implications for grain size, shape and materials variations in diffuse clouds are discussed. This work has been supported by NASA grant NAG5-1743.
