Tom Van Flandern writes:

Is that the best you can do? The quick rise in ultraviolet light
indicates the probe hit a hard surface ... possible crystalline
silicates ... large surface craters ... possible layering ... overall
appearance indistinguishable from an asteroid ... no increase in water
emission or other volatiles

From IAU Circular 8571, dated 2005 July 22:

] Spectral features due to water ice,
] water vapor, and carbonaceous materials (carbonates and
] hydrogenated aromatic hydrocarbons) were detected in the 5.8-7.2-
] micron region.

] The ejecta spectral signatures were
] detected from the time of impact through at least 41 hr afterwards,
] but by 121 hr after impact all spectral signatures above the pre-
] impact levels were absent.