Laser Heating of Coal Particles in the Source of “Time-of-Flight” Mass Spectrometer

Abstract

DURING general investigation of the processes that occur in the combustion of pulverized coal, experiments have been undertaken to develop methods for determining the nature of products formed by the rapid thermal decomposition of coal particles, especially those evolved in the very early stages of decomposition. In previous work1 the yields of the stable decomposition products evolved from small coal particles during the first millisecond of flash heating were determined by quenching the products in an inert atmosphere. Using this method, however, it was not possible to determine whether free radical fragments constituted part of the primarily evolved species. Recent work on the pyrolysis of lump coal using a laser beam has suggested that free radicals of molecular weight of about 100 are evolved2, but in these experiments the products arose both from complete vaporization within the crater formed by the direct beam and from relatively slow low-temperature pyrolysis around this crater.