Chemical reactions at very low temperatures. A rotating cryostat for mixing reactants at 4·2°K

Abstract

lt is not normally possible to conduct free radicalreactions so that only a single elementary step in the reac-tion sequence takes place, because the products of reaction are extremely reactive. In an attempt to control these reactions more closely and to preserve the very reactive radical chain carriers as products of primary reaction, a novel reactor ls designed and constructed for use at the temperature of liquid helium. The two participants in a reaction are laid down as alternate solid layers on top of each other; the more reactive species being deposited as a fraction of a monolayer sandwiched between several monolayers of the less rcactive material. The reactants are condensed on the outside surface of a spinning refrigerated drum to produce multilayer deposits about 0.l to 0.5 mm thick, which are then examined by reflection spectroscopy. Preliminary results suggested that HCO is preserved when hydrogen atoms are deposited between layers of solid carbon monoxide. A reaction product absorbing continuously in the ultra-violet is found when hydrogen atoms are interspersed between layers of oxygen molecules. (auth)