We present here the design details of a high-pressure pulsed valve that generates intense supersonic jets. The measured rotational contours of Aniline indicate that temperatures lower than 0.5 K can be achieved before the formation of clusters with the He carrier gas. The spectral shifts and vibronic structure of Anthracene-He n clusters (nϭ1-6) are showing some surprising features.

A pulsed valve connected to a closed-cycle cryostat was optimized for producing helium droplets. The pulsed droplet beam appeared with a bimodal size distribution. The leading part of the pulse consists of droplets suitable for doping with molecules. The average size of this part can be varied between 10(4) and 10(6) helium atoms, and the width of the distribution is smaller as compared to a continuous-flow droplet source. The system has been tested in a single pulse mode and at repetition rates of up to 500 Hz with almost constant intensity. The droplet density was found to be increased by more than an order of magnitude as compared to a continuous-flow droplet source.

We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

An improved method for generating intense, collimated cluster beams is described. The beam mass distribution is interrogated by a single-photon ionizer and a novel time-of-flight mass spectrometer, optimized for very high mass detection.

No abstract