THE PULSED-ARC CLUSTER ION-SOURCE (PACIS)

A new cluster source, the "PACIS", has recently been developed [1, 2]: a pulsed high-current arc is fired between two electrically isolated electrodes. In a stream of carrier gas, the nascent metal plasma cools down, thus undergoes significant aggregation. After supersonic expansion into high vacuum, the resulting cluster ions will be subject to investigation. Here, we present the current state of the source development and further technical details. The integral intensity is estimated by film thickness measurements and yields a deposition rate of, e.g., up to 2 angstrom per shot for lead. About 10% of the emitted material turns out to be charged. Time-of-flight measurements show similar cluster ion mass spectra as they are known from laser vaporization. Already single shot mass spectra display complete n-series which can be followed to n almost-equal-to 40. For heavy clusters, a significant velocity slip is estimated from the beam velocities.