Absolute yields of hydrogen from the ?-radiolysis of hydrocarbon gases have been obtai~led by relating the hydrogen produced to saturation ion currents measured in the radiolysis vessel. \.alucs for GII, of 1.28, 1.20, 6.25, 5.40, and 5.00 have been estimated for ethylene, propylene, propane, n-butane, and isobutane respectively. These values are consistently lower than those obtained previously with a-rays, and this is discussed as a n effect of radiation qualit).. ;\rguments arc advanced for the use of M / N , the yield per ion pair, rather than G, a s a measure of yielcls in the racliolgsis of gases.Despite the very considerable amount of work done in recent years on the y-radiolysis of gases, the dosimetry of these systems, especially the absolute dosimetry, is very far from satisfactory. iVIost workers have calculated G-values by a comparison with other gas-phase "dosimeters", such as ethylene, acetylene, or nitrous oxide, using a correction for differences in stopping power (usually simply an electron-density correction), although these "dosimeters" have never been well calibrated for gamma radiation. Others have simply estimated the energy absorbed from the measured y-ray flux, with some assunlptioll about a n energy absorption coefficient for the gas, which can lead to large errors for gases a t atmospheric pressure or lower. The basic difficulty in y-ray dosimetry a t these pressures is that in nlost cases the direct absorption of y-radiation in the gas is quite negligible, and almost all the chemical effects are due to secondary electroils ejected from the \valls oi the irradiation vessel.accurate estimation of absorbed energy beconles very difficult in this situation, especially in the absence of precise knoniledge of the energ). distribution of the electrons, and of their rate of eilergy loss in the gas.Surprisingly little use has been made in the radiation chemistry of gases of the measurenlent of saturation ion currents in the gases themselves during irradiation. Essex and co-worlxrs (I), ~1siilg very \veal< sources of a-rays, have related chemical yields to saturation ion currents for a few gases, but the method has never been applied to y-radiolysis systems. I t appears to offer a very simple way to obtain absolute yields in the y-radiolysis of gases, and the present paper describes the results of some illeasurements made with simple hydrocarbons.Unlilce a-rays, r-radiation cannot be restricted conveniently to a region between two parallel plates, so a cylindrical reaction vessel, shown in Fig. 1, was used in which the cylirldrical wall itself was the collecting electrocle. 'The vessel was made of 60-mm o.d. Pyrex tnbing, while the cathode and guarcl ring consisted of graphite coatings, originally applied as colloidal graphite irl aqueous suspension. The anode was a tungsten wire of 1.5-nlm diameter, while tungsten leads through the glass walls made connections to the cathode and guard ring. 'The vessel \\,as thoroughly baked under vacuum before its initial use, and before each experiment...

The effect of electric fields on the y-radiolysis of ethane, propane, and the butanes has been investigated briefly a t 800 mm pressure, with dose rates between 2X101° and 400X1010 ev/cc sec. Yields of hydrogen were reduced when a saturation field was applied, except with ethane a t low dose rate, where a slight increase in hydrogen yield was observed. With propane and n-butane, the yield of hydrogen in the presence of a saturation field was independent of dose rate, while with ethane, it decreased with decreasing dose rate. A t the same time, a dose rate dependence was discovered in the simple radiolysis, in the absence of any field, of ethane, propane, and n-butane, a decrease in the yield of hydrogen a t low dose rates being observed. An explanation of these observations is suggested in terms of a competition between neutralization of ions in the gas phase and diffusion of ions to the wall. High dose rates should favor the former process, and low dose rates the latter. At sufficiently high dose rates, all ions should be neutralized in the gas phase. A t sufficiently low dose rates, all ions should diffuse t o the wall before neutralization, and it is suggested that the radiolysis under these conditio~ls should closely reseinble that ill the presence of a saturation field a t higher dose rates.The application of an electric field to a gas during irradiation offers a potential means of -distinguishing between products arising from ions and those forined from neutral species. In practice, the interpretation of the results is very complex, and except for the work of Essex and his collaborators a t Syracuse (I), mostly concerned with a-radiation, the method has not been widely used in radiation chemistry. The present work was undertaken to study the effects oi electric fields on the 7-radiolysis of some simple hydrocarbon gases, using a saturation-current method (2) to measure absolute product yields. In the course of the work, a hitherto unsuspected dependence of hydrogen yield on dose rate was discovered, which appears to be closely related to the action of applied fields on --the radiolysis. EXPERIMENTALThe preparation and purification of hydrocarbon samples for irradiation have been previously described (2, 3). Gases were irradiated in cylindrical vessels of 60-mm 0.d. and about 500-to 600-cc volume. Two experiments with propane were done in a smaller vessel of the same design and length, but with about one-half the diameter and one-quarter the \~olume. The measurement of saturation ion current and of hydrogen yield has been described (2). Electric fields were always applied with the central electrode positive, so that the positive ions were drawn to the other electrode, the graphite-coated wall of the cylindrical vessel. Hydrogen was the only product measured, and the extent of decomposition was always small enough that "internal" scavenging was negligible, and the measured yields were very close to their true initial values (3). Ethylene scavenger was added in some experime~lts, in which case the hyd...

Aliphatic alcohols increase the yields of N20 observed in the radiolysis of NO solutions and are oxidized to the corresponding aldehyde in the process. The following reactions occur in addition to those previously suggested 1 for the NO radiolysis :OH+ROH +H2O+*ROH

Recent publications ( 1 4 ) have dealt with the effect of electron scavengers on the radiolysis of simple inorganic gaseous hydrides. We would like to present some results of a preliminary study on the radiolysis of gaseous H2S that are, in general, quite different from those above (14).Matheson C.P. grade H,S (99.7 %) was found to contain CO, (-0.2 %) and CS, (< 0.001 %) as impurities when checked by gas chromatography. A 3 m Poropaq Q column maintained at 65 "C, helium carrier gas, and thermal conductivity detection were used (5). After several freezepump-thaw cycles at -130 "C, the concentration of CO, was reduced to -0.005 %. Some of this H,S was irradiated to a dose of about 4 x lo2, eV g-l. After degassing at -196 "C, this H,S was found to contain -0.005 % CO, and no detectable amount of CS,. Radiolysis experiments with the pre-irradiated H,S gave identical results to the untreated H,S, and so the latter was used for the bulk of the work presented here. SF, and N,O (Matheson) were degassed several times by freeze-pump-thaw cycles at liquid nitrogen temperature and were used without further purification.Dosimetry was effected by ion current measurements in vessels similar to those described by Back et al. (6), the extrapolation method of Scott and Greening (7) being used to obtain saturation ion currents. The same vessels were also used as irradiation vessels, as were ordinary Pyrex vessels of similar geometry. All vessels were baked out at 400 "C, to a pressure of less than lo-' Torr prior to filling and irradiating.

Ion currents produced in hydrogen sulphide in a cylindrical ion chamber by y-radiolysis have been measured. Saturation points on the ion current curves were located by application of general recombination theory. These saturation currents were then used to estimate that the average energy W(H2S) required to produce an ion pair in hydrogen sulphide is 25.3f0.4 eV. Other values determined were W(CH3SH) = 25.1 f0.4 eV, W(N20) = 32.7f0.4 eV and W(SFs) = 35.0f0.4 eV. Hydrogen and sulphur are produced upon irradiation, with radiation yields (molecules per 100 eV energy absorbed, or G values) G(H,) = 7.0k0.2 and G(S) = 7.0f0.4 relative to W(HzS) = 25.3 eV. Possible use of the production of hydrogen from the radiolysis of hydrogen sulphide as a gas dosimeter is discussed.