Charles D. Jonah

A wide−time range pulse radiolysis system of picosecond time resolution

A stroboscopic pulse radiolysis system is described which detects the transient absorption generated by a 20 psec pulse from a 20 MeV linear accelerator. The time resolution is obtained by using, as the analyzing light, the short pulse of ?erenkov light generated by the portion of the electron beam which passes through xenon. The remaining portion of the electron beam is delayed by passing around a 270° magnet and the delay of the light may be varied by an optical delay line. Block diagrams for the electronics and the optics are given. The magnitude of sources of errors are discussed.

Hydrated electron revisited via the Feynman path integral route

Abstract The Feynman path integral formulation of quantum statistical mechanics is used to study the hydrated electron. The results show that no shell structure is apparent at room temperature and the electron aligns the water molecules by the O-H bond dipole and not the molecular dipole.

Picosecond molecular relaxations during electron solvation in liquid alcohol and alcohol-alkane solutions☆

Abstract The time evolution of the solvated electron in a series of linear alcohols has been measured. A correlation between the time for monomer rotation τ 2 and the solvation time τ s seems to hold for the series. The mechanism of solvation is discussed with reference to the experimental data.

Pulse radiolysis of cyclohexane: The identity of the high-mobility positive ion

Abstract Previous experimental observations and new pulse radiolysis results concerning the high-mobility positive ion in cyclohexane are examined. Apparent disagreement among these observations concerning the existence of a high-mobility positive ion can be explained if there are two positive ions of major importance in cyclohexane radiolysis. The possibility is examined that the c -C 6 H 12 + ion has a “normal” mobility and that hydride transfer or proton transfer, involving c -C 6 H 11 + or c -C 6 H 13 + respectively, is responsible for the observed high mobility.

LET dependence of transient yields in the pulse radiolysis of aqueous systems with deuterons and alpha particles.

The variation of G (

Decay of geminate ions in hexanes

e{}_{{\rm aq}}{}^{-}

A Short History of the Radiation Chemistry of Water

) with beam penetration depth, and hence, with LET, has been measured in water using 10-μsec pulses of 20-MeV deuterons and 40-MeV α p...

Picosecond observations of electron solvation in dilute polar fluids

Abstract A direct measurement of the geminate decay process between the electron and the positive ion in n -hexane and cyclohexane is presented. For n -hexane, the decay is that which has been predicted for geminate ion decay processes in which the distribution function for the distance between positive and negative ions is exponential. For cyclohexane, the decay is well described by an exponential process with a decay time of 0.58 ns.

Reactions of electrons in high-concentration water solutions—A comparison between pulse-radiolysis and positron annihilation lifetime spectroscopy data☆

The first hundred years of radiation studies have greatly clarified the chemical processes that are induced by radiation. While the fundamental ionization processes are similar in all systems, properties of the medium such as phase, polarity and composition can greatly affect the chemistry. In all systems, one needs to understand what chemical species are formed, what the internal energies are, how they are dispersed spatially, and what reactions can occur. In this review, the progress that has been made in understanding the chemistry that occurs after a radiolysis event for liquid water is outlined as an example of how progress has been made in radiation chemistry.

Design of an optical cell for pulse radiolysis of supercritical water

Abstract Electron solvation has been studied in dilute polar fluids in order to quantify the role of the fluid in the proposed mechanisms of electron trapping and solvation. In a series of dilute alcohol-alkane systems, the picosecond evolution of the absorption spectrum is shown to be a sensitive function of the local liquid structure and dynamics. A solvation mechanism is outlined which correlates the absorption and mobility data from neat and dilute polar fluids.