Laser furnace apparatus

Endohedral metal fullerenes can be detected in relatively small amounts in the mass spectra in the laser vaporization cluster beams (vide supra). However, macroscopic quantities of these compounds may be produced rather readily either by vaporization in a laser furnace apparatus or by arc-burning of a composite rod of graphite and the corresponding metal oxide. In Fig. 4.50, a mass spectrum which illustrates the formation of a series of fullerene endohedral yttrium complexes obtained by laser vaporization of a composite graphite/ Y2O3 rod at 1200 ""C is reproduced. Among these species there is also one, Y2 Cs2, which corresponds to the inclusion of a metal cluster in the fullerene ball. 

Figure 1. Tube furnace laser vaporization apparatus used by Haufler et al. (1991) to produce high yields of C 0F. The 532 nm doubled Nd YAG pulse vaporizes C from the rotating graphite target into the inert carrier gas stream. The fullerenes condense just outside the oven on the tube wall.

The laser ablation apparatus consists of a quartz tube inside which a composite graphite disk is placed for laser irradiation. A furnace enwraps the quartz tube, thereby supplying a high... 

In recent years there has been renewed interest in treating coal at high temperatures both by rapid processing in the more conventional type of carbonization apparatus (I) and by using such devices as flash tubes (5, 12, 13), lasers (13), arc image furnaces (9, 11), and plasma jets (3). All these methods produce conditions whereby the coal can be heated rapidly to a temperature well in excess of 1000°C. followed by quenching of the products. The work described here is an investigation into the reactions of coal in a plasma jet and has been reported briefly elsewhere (3). 

Haufler et al. (1991) set up the apparatus shown in figure 1 to explore the effect of wall temperature on fullerene yields by laser vaporization. In this apparatus graphite is vaporized from the end of the graphite rod by a softly focused pulsed visible laser (Nd YAG, 532 nm, 5-ns pulse, 300 mJ pulse-1). When the walls of the tube are at room temperature no fullerenes are found in the resulting soot only when the walls of the tube were heated to 1000 °C were any fullerenes obtained. As the furnace temperature was increased further, the yields increased reaching 20% Cf0F at 1200 °C, which was the maximum temperature obtainable with this apparatus. 

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