Irradiation of gaseous mixtures of ammonia and phosphine with Co-60 gamma rays yields hydrogen, red phosphorus, and nitrogen. Attempts to find other products have been unsuccessful. Hydrogen yields are larger than predicted from the assumption of an "ideal" mixture, in which the ammonia and phosphine decompose proportionately to the dose each absorbs, but nitrogen yields show a striking depression. This occurs even in mixtures with less than 0.1 mole percent phosphine. Phosphine appears to be acting as an efficient radical scavenger, via reactions such as ${\rm NH}_{2}\cdot +{\rm PH}_{3}\rightarrow {\rm NH}_{3}+{\rm PH}_{2}\cdot $ and ${\rm H}\cdot +{\rm PH}_{3}\rightarrow {\rm H}_{2}\ {\rm PH}_{2}$ . The phosphino radical reacts further to yield (finally) phosphorus and hydrogen. By comparing the radiolytic decomposition of ammonia in a mixture containing a few mole percent phosphine and in the pure state, it can be shown that roughly one phosphine is removed for each ammonia that is prevented from decomposing in the mixture. This "protective" effect occurs at least partly via radical scavenging reactions.

A limited study has been made of the gamma radiolysis of methyl iodide vapor and mixtures of phosphine and methyl iodide in the gas phase. Analyses of methane and hydrogen yields from irradiation of the pure vapor at 270 Torr show that both are proportional to absorbed dose from $1\times 10^{20}$ to $4\times 10^{20}\ {\rm eV}$ , with $G({\rm CH}_{4})=2.3$ and $G({\rm H}_{2})=0.6$ . Both yields show a dependence on methyl iodide pressure. $G({\rm CH}_{4})$ increases with pressure above 200 Torr, but $G({\rm H}_{2})$ falls off. The mechanism for methane production is presumed to involve hot methyl radicals. Hydrogen production may be via a molecular elimination or hot atom process. Those mixtures containing a few mole percent phosphine show a greatly enhanced methane yield. A maximum $G({\rm CH}_{4})$ of 12.6 occurs in a mixture containing 3.5 mole % phosphine and in which 99% of the radiation dose is absorbed by methyl iodide. This yield probably approximates the G for methyl radical production in pure methyl iodide vapor. In mixtures with greater phosphine concentrations the methane yield falls off sharply, perhaps due to an energy transfer process.

Comparison studies of the decomposition in the gas phase of pure phosphine and pure ammonia by cobalt-60 gamma rays show that both compounds are broken down to their elemental constituents. Results of mass balance experiments with pure phosphine indicate that the overall radiolysis reaction is ${\rm PH}_{3}\rightarrow {\rm P}_{\text{red}}+{\textstyle\frac{3}{2}}\ {\rm H}_{3}$ . G for hydrogen production is 11.3 (molecules formed per 100 eV absorbed energy), over the dose range $0.4\times 20^{20}\ {\rm eV}$ to $5\times 10^{20}\ {\rm eV}$ , beyond which the G value decreases. From 50 Torr to 1 atm the product yield is proportional to phosphine pressure, extrapolating to zero yield at zero pressure. Yields of nitrogen and hydrogen from the radiolysis of gaseous ammonia are proportional to dose from $1\times 20^{20}\ {\rm eV}$ to $5\times 10^{20}\ {\rm eV}$ , with G values of 1.5 and 4.5, respectively. The total product yields extrapolate to zero yield at zero dose. The G values are not dependent on ammonia pressure from 100 Torr to 1 atm, and the product yields extrapolate to zero at zero pressure. Measurement of nitrogen by two methods gives very close agreement and indicates that the formation of hydrazine is insignificant. The absorbed dose rates were determined by measuring the hydrogen yield from irradiated ethylene, assuming a G value of 1.2 and electron stopping powers (relative to ethylene) of 1.041 for ${\rm PH}_{3}$ and 0.661 for NH 3 .

The following substances have been identified as minor products in the gamma radiolysis of liquid cyclopentane at $3\times 10^{22}$ eV total dose: 1,4-pentadiene; 2-pentene; cyclopentadiene; 1,3-pentadiene; ethyl cyclopentane; vinyl cyclopentane; n-heptane; n-octane; propyl cyclopentane; propenyl cyclopentane or propyl cyclopentene; n-decane; pentenyl cyclopentane or n-pentyl cyclopentene; n-pentyl cyclopentane; and cyclopentyl cyclopentene. The determination of these products was by parent mass number, gas chromatographic retention times, and/or boiling points of the compounds. Ultraviolet spectroscopic studies of the radiolysis of solutions of cyclopentadiene in cyclopentane are also described.