Interaction of intense laser pulses with atomic clusters

We examine the interaction of intense, femtosecond laser radiation with the large (50--200 \AA{}) clusters produced in pulsed gas jets. Both experiment and simulation show that the plasmas produced during these interactions exhibit electron temperatures far in excess of that predicted by above-threshold ionization theory for a low-density gas. Efficient heating of the clusters by the laser is followed by rapid expansion of the clusters and long-lived x-ray emission from hot, decaying, underdense plasma. \textcopyright{} 1996 The American Physical Society.