No abstract

A study has been made of the radiolysis of aqueous solutions of NO?, NO2 and Fe(CN):-within the first millisecond after exposure to a submicrosecond pulse of 15 MeV electrons. The overall reaction of the electron adduct of NO3 with water has a time constant of 9.5 ps at 25°C and it is catalyzed by Hf. The reduction product of nitrite, 20H-, appears to originate from two processes with time constants of 18 and < 2ps respectively. The reduction of ferricyanide is probably complicated by aquocomplex formation. The rate constant for CH,OH+ Fe(CN)%-+CH20+H++The application of the conductivity technique to the measurement of kinetics of transient ions produced by pulse radiolysis has been described. Another valuable feature of this approach is the possibility of elucidating the mechanisms of the reactions involving such ions. The method is exemplified in this paper using as solutes three anions commonly employed as radical scavengers in the radiation chemistry of aqueous solutions. EXPERIMENTALThe conductivity technique and procedure were as described previously. Briefly, solutions in a conductance cell were irradiated with single 0.4 ,us pulses of 15 MeV electrons. The electrical conductance change AS 0-' was detected by an oscilloscope as a proportional voltage change A V mV. The dose in the pulse was 30-200 rad based on a radiation yield of positive or negative ion formation in pure water = 3.4 molecules/100 eV1. At any instant after pulse irradiation, A S = K;l &ACJi Re', where ACi and Aj are respectively the concentration (mol l.-') and molar conductance (cm2 0-l) of ionic species i, and K, the cell constant in cm-l. Molar conductances were literature values supplemented by measurements in the irradiation cell. Values at 25°C for NO?, NOT , Fe(CN)z-, Fe(CN)i-,

The rate constants and Arrhenius activation energies for the reaction of ROH: with RO-in the liquid state have been measured for R = CH3, C2H5, l-C3H7 and 2-C3H7. The values at 25°C are 7.05 x lO'O, 3.0 ; 4.59 x lo1', 4.3 ; 2.40 x lO'O, 5.9 ; and 1.50 x 1O1O 1. mol-1 s-I and 7.3 kcalmol-1 respectively. Evidence is presented that, for all the solvents studied (a) the rate coefficients for ROH:+e; are nearly the same as the above, (b) the rate data (including the effect of traces of water) are adequately accounted for by diffusion theory, (c) A(e;) m A(R0-) and ( d ) g (free-ions) M 2.1-* research carried out at A.E.R.E., Harwell, Berks. t g(z) denotes the yield in molecules per 100 eV of a transient species Z.

A sensitive technique is described for the study of transient ionic intermediates produced in the radiolysis of liquid solutions. Results are given for the radiolysis of water in the pH range 4-10. Rate constants for eag+H30f and OH-+H30+ are in good agreement with values obtained by other methods. Activation energies have been measured for both reactions and for the diffusion of the hydrated electron.

AbstraQ. We model the local electronicstructure around acore-ionizedsite inasimple metal self-consistently using an embedding technique. We consider the local densities of stales of Na, Mg and AI and calculate from first principles KLV Auger profiles. The success of this approach is assessed by comparison with experiment and with approximations which may be used to simplify the calculation. The agreement with experiment is on the whole good although some discrepancy arises for the case of W . , V lineshapes.