Simultaneous temporally and spatially resolved measurements of the phase ch
ange and reflectivity of S- and P-polarized femtosecond laser probes are ob
tained from hot expanded states produced by femtosecond laser heating of a
solid aluminum target. The combined set of data provides an integral test o
f equation-of-state models in a regime up to 10 Mbar and densities of 0.01-
1 times solid. The results suggest that target stoichiometry at the few A l
evel should be considered in the analysis of phase and reflectivity measure
ments in such experiments. (C) 2001 American Institute of Physics.