A new high transmission infinite range mass selector for cluster and nanoparticle beams

A new mass selection technique has been developed, which allows one to size-select charged particles from atoms to nanoparticles of almost unlimited size. It provides a mass resolution of m/Delta m = 20-50 and a transmission of about 50% for the selected size, both independent of mass. The technique is based on the time-of-flight principle, but differs fundamentally from time-of-flight mass selection normally used. The basic idea is to use time-limited high voltage pulses to displace laterally a preaccelerated ion beam, without changing its direction or shape. As the movement of the ions perpendicular to their original beam direction is independent of their forward velocity, mass resolution and calibration does not depend on the ion beam energy. A mass selector of this type has been implemented successfully into a cluster deposition experiment and has proven to be reliable and simple to operate. (C) 1999 American Institute of Physics. [S0034-6748(99)03712-0].