A previous discussion [J. Acoust. Soc. Am.85, 1560–1568 (1989)] on the energy band structure of target materials, suitable for generation of ultrashort optoacoustic pulses by photostriction, is extended and formalized. Details of the band structure necessary to suppress thermalization by holes are included. It is pointed out that the material should exhibit suitable gaps between valence bandsinadditiontohaving suitable gaps between conduction bands. The conditions that must be satisfied in order to prevent thermalization by electronsaswellasholes, a key feature necessary in the production of ultrashort pulses, are formalized. Some examples of materials approaching an ‘‘ideal’’ band structure are given.