Optical emission from argon gas excited with alpha particles has been studied to determine if electronic states of long lifetimes are excited by swiftly moving charged particles as has been observed in studies of ionization. The spectrum from argon showed a continuum which could be separated into three distinct bands with maxima at 1300, 1800, and 2000 Å. The light intensity of the 2200-Å band was readily quenched with the addition of about 2% of CH4, CO2, O2, and Kr. The 1800-Å band was quenched more slowly than the 2200-Å band by the impurity gases. The results support the notion that alpha-particle excitation of argon at high pressures leaves the argon in long-lived states of about 11.5 or 14.5 eV. The observed continua appear to arise mainly from Franck—Condon transitions between two excited states and the ground repulsive state of the argon dimer which forms as a consequence of the long lifetimes of the excited atoms.

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This report is published in the interest of providing information which may prove of value to the reader in his study of effects data derived principally from nuclear weapons tests. This document is based on information available at the time of preparation which may have subsequently been expanded and re-evaluated. Also, in preparing this report for publication, some classified material may have been removed. Users are cautioned to avoid interpretations and conclusions based on unknown or incomplete data.

825are somewhat greater than those estimated from 20" acidity data; however, this is the direction expected, and of the approximate magnitude predicted, from studies of the temperature coefficient of U(V1) hydrolysis in nitrate medium.*aThe question of the importance of other species which may be present in minor amounts is no more resolved by the present results than by the earlier study. For example, it was apparent that about as satisfactory an interpretation could be obtained with a scheme including UOzOH+, although there would be considerable uncertainty in the values of el,l. Similarly, our conclusions for the perchlorate solutions agree in general with those of SuttonJ6 though he includes a small contribution of the (3,4) species.The most important point of disagreement with the interpretation of acidity measurements on a core-link modelll seems to be resolved, since the St>ockholm group now postulate an important contribution by the (3,5) species, which is not of the core-link type.l2 They still postulate the presence of several higher corelink species, for which we do not find any evidence in our results, but since the constants quoted for these species are rather low, the remaining disagreement is perhaps more in a conceptual model of hydrolysis rather than in a practical description of U(V1) solution chemistry. From a recent publication,13 it appears that even this disagreement may no longer exist.Acknowledgment.-We wish to express indebtedness to Kurt A. Kraus for many helpful and stimulating discussions and to Neva Harrison for technical assistance.The W value (average energy loss per ion pair) for a-particles has been measured in a number of binary gas mixtures of molecular gases as a function of the fract'ional pressures. The W of the mixture ( Wij) can be represented in terms of the 14"s of the pure constituent gases Wi, Wj) and the fractional pressures ( P i , Pj) by the relation:, in whichfij is a constant determined empirically for each pair of gases. These constants verynearly satisfy the relationshipfij = fj/fi = (fj/fk)/(fi/jk) = jkj/jki,where i, j, and k refer to any three gases. Thus, if the followingj-values are assigned to the gases in this study (Nz, 1;COz, 1.8; H,, 0.5; 02, 1.3; CH,, 1.8; CeH4, 3.4; GH6, 3.5; CJ&, 4.5; C,Hs, 4.5; C9H8, 6.3) then the constant f i j determined from the ratio of any two of these will serve to predict the W of any mixture of these two gases with an accuracy better than 1%. Slight departures from the W predicted by the above equation have been noted in the case of nitrogen mixtures, indicative of an effect similar to t'hat observed in the noble gases when small amounts of impurities are added.

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