New Developments in Making Compounds and Materials by Condensing Gaseous High-temperature Species at Atmospheric or Low Pressure

摘要

It is well known that the use of high temperatures permits the formation of a wide range of gaseous atomic and molecular chemical species which are often unobtainable by other means. Many of these species such as the free atoms of the metals or low oxidation state oxides and halides of Group 13 and 14 elements have the potential both thermodynamically and kinetically to be chemically very reactive. As soon as the temperature is lowered the species become metastable and tend to recombine to form the less reactive gaseous or solid elements or compounds from which they were made. This recombination can be very rapid and often special conditions have to be established to make use of the species while they are still reactive. Deriving useful chemistry from such species began to be a lively area of research in the 1960s following work by Skell on carbon vapour chemistry. There was a frenzy of activity in the 1970s following the first work on transition metal atom chemistry at Bristol. Developments have continued to the present but undoubtedly the biggest surprise in the 1980s and early 1990s again involved carbon in the synthesis of fullerenes, the remarkable molecular allotropic forms of that element.