Fourth generation cryogenic neutral cluster beam apparatus for studying fundamental properties of metallic clusters

Abstract

A cryogenic beam apparatus for studying neutral clusters has been built and tested. The lowest beam temperature reaches less than 9 K at a repetition rate of 20 Hz. Mechanical decoupling from the refrigerator avoids misalignment during temperature ramping. Adopting a permanent magnet based magnetic deflector eliminates the hysteresis and electric noise of the traditional electromagnet and offers excellent reproducibility of the applied magnetic field. The mass spectrometer can operate in either Mass Spectroscopy Time-Of-Flight mode or Position-Sensitive Time-Of-Flight mode with spatial resolution better than 7 μm. Its performance is demonstrated with niobium and cobalt clusters.

Out-of-focus spatial map imaging of magnetically deflected sodium ammonia clusters

“…Position-resolved mass spectrometry is an often employed detection technique in deflection experiments. [16][17][18][19][20] This method exploits different flight times for different cluster positions to resolve deflection spectra for multiple masses in a single measurement, allowing the resolution of the position and mass simultaneously. However, as the ionization position is inferred from the time of flight, it does not directly offer an image of the deflection pattern, and requires a compromise between mass resolution and position resolution.…”