Production of Hydrogen Atoms by Hot Tungsten

Langmuir (48) showed that if hydrogen gas were introduced into a bulb containing a heated tungsten filament, and the walls cooled in liquid air, a continuous decrease in pressure was observed. He supposed hydrogen molecules dissociated on the filament to give chemisorbed atoms, which evaporated and were trapped on the cold walls. 

Bryce (49) reexamined the reaction, using a layer of molybdenum oxide on the walls of the vessel to trap the atoms. This method of trapping he found more efficient than the previous one. Over the temperature range 1148 to 1420° K. and pressure p 2.4X10 to 37X10 mm. mercury, n, the number of hydrogen atoms produced per cm. per sec. is 

For equilibrium, 0 the fraction of surface covered by atoms, for a hydrogen molecular pressure ps, is given by 

K is the equilibrium constant in atmospheres for H2 2H in the gas phase. mi is the mass of a hydrogen atom, wij that of a molecule, a is the probability that an atom striking a bare site is adsorbed, y the probability that an atom will evaporate, d the probability that a molecule striking a surface will split up into an adsorbed and a gaseous atom, and y the probability of the reverse step to the last named. 

Process (a) then yields for the rate of production of atoms, v, 

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Bond Type in the Adsorbed Film Production of Hydrogen Atoms by Hot Tungsten Recombination of Hydrogen Atoms The Parahydrogen Conversion. ... 

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