Energy-selected metal clusters, production

Fig. 1.35. Experimental setup for the investigation of gas-phase catalytic activity of mass-selected metal clusters. The cluster ions are sputtered from solid targets with a CORDIS, mass-selected (Qi), and guided at low energies (Qo and Q2) into the temperature controllable octopole ion trap. By means of appropriate switching of the lenses Li and L2, the reaction products are extracted and subsequently mass-analyzed by another quadrupole mass filter (Q3) [32,186]...

The aluminium beam is produced by the technique described in previous works of Smalley and co-workers for the generation of supersonic metal clusters [17,18]. However, as our goal is to produce atoms and not clusters, our set up stands out with several particularities (i) firstly we use an excimer laser (Lambda Physik EMGIOIE) operated at 249 nm with an unstable resonator, rather than a doubled Nd-Yag laser. A fraction of the output ( 7mJ) is selected by spatial filtering and focused to a 0.4 mm diameter circular spot on the rod (96% A1 - 4% Mg alloy). The combination of the 5 eV photon energy and the high fluence ensures rupture of all the Al-Al bonds in the ablated material. A higher production rate of atoms... 

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