Electron pulse radiolysis

Baxendale, J. H., Busi, F. (eds.) The study of fast processes and transient species by electron pulse radiolysis, D. Reidel Publishing Co., Dordrecht 1982... 

Sauer, M.C., Jr. In Study of Fast Processes and Transient Species by Electron Pulse Radiolysis Baxendale, J.H., Busi, F., Eds Reidel Dordrecht, 1982 601 pp. 

Recent technical developments in laser Raman spectroscopy have made it possible to measure the Raman spectra of short-lived transient species, such as electronically excited molecules, radicals and exciplexes, which have lifetimes on the order of nano- (10-9) and pico- (10-12) seconds. These shortlived species may be generated by electron pulse radiolysis, photo-excitation and rapid mixing. However, the application of electron pulse radiolysis is limited in its adaptability and selectivity, while rapid mixing is limited by mixing rates, normally to a resolution on the order of milliseconds. Thus, photoexcitation is most widely used. 

The pulse radiolysis method is a powerful means of studying the kinetics in radiation chemistry. We investigated the ion beam interaction with polystyrene using this method. It is a unique system, because pulse radiolysis is usually an electron pulse radiolysis. 

The decay of the low dose-time profile (I) is in agreement with that obtained by the electron pulse radiolysis study of polystyrene [37, 38], the lifetime of which was about 20 ns. The straight line in Fig. 6a corresponds to this lifetime. 

On the other hand, the high dose-time profile (II) shows a different decay from that by electron pulse radiolysis [37, 38]. 

Fig, 6a, The irradiation time dependence of the intensity of the excimer fluorescence (328.5 nm) from a polystyrene thin film (0.5 pm thick) irradiated with 0.6 MeV He ions. From Ref. 36. (b) Time profiles of the excimer fluorescence (328.5 nm) from a polystyrene thin film (0.5 pm thick) irradiated with 0.6 MeV He ions. The low dose-time profile (I) was recorded in the irradiation time of 0 s-139 s, and the high dose-time profile (II) in the irradiation time of 1839 s - 3839 s. The straight line corresponds to the fluorescence lifetime obtained by the electron pulse radiolysis study [38]. From Ref. 36... 

Fig. 7. Time profiles of the excimer from polystyrene resist films (0.5 pm thick) irradiated with ions. These time profiles were not influenced by the quenching seen in Fig. 6. The straight lines correspond to the fluorescence lifetime obtained by the electron pulse radiolysis study of polystyrene [38], From Ref. 35...

Since its spectroscopic discovery, a large number of time-resolved experiments were carried out to clarify the relaxation dynamics of the solvated electron. The first experimental studies of the formation dynamics of electrons in liquids started with electron pulse radiolysis... 

Asmus K-D, Janata E. (1982) Conductivity monitoring techniques. In Baxendale JH, Busi F (eds.). The Study of Fast Proeesses and Transient Species by Electron Pulse Radiolysis, pp. 91-113. D Reidel Publishing Company. 

As one can notice in the Fig. 4 the signal obtained from a microsecond pulse of 1-GeV carbon ions has a rather good signal-to-noise ratio and could be useful as it is in the electron pulse radiolysis. However, this newly developed method for ion currently suffers from a lack of data and it is not yet so easy-to-use to be widely exploited. 

Parent radical cations derived from alkanes and alkyl chlorides can be directly observed in the nanosecond time domain by time-resolved spectroscopy such as laser flash photolysis and electron pulse radiolysis. Especially the latter one enables the direct ionization of the solvents independently on the optical properties of the sample and a well-defined electron transfer regime according to Eq. (2) or (3). Representative examples of the radiolyfic generation of solvent radical cations are given in Eqs. (4) and (5a) for the cases of 1-chlorobutane and -decane. ... 

The unrestricted and free electron transfer (FET) from donor molecules to solvent radical cations of alkanes and alkyl chlorides has been studied by electron pulse radiolysis in the nanosecond time range. In the presence of arenes with hetero-atom-centered substituents, such as phenols, aromatic amines, benzylsilanes, and aromatic sulfides as electron donors, this electron transfer leads to the practically simultaneous formation of two distinguishable products, namely donor radical cations and fragment radicals, in comparable amounts. 

A historical perspective on these developments is given in the first chapter by Jonah. Janata offers a detailed account of the key technique of electron pulse radiolysis, then firmly placed on the modern stage of ultrafast techniques in the chapter by Belloni et al. By far the most common detection scheme is that of transient optical absorption, however chapters by Warman and de Haas (on microwave conductivity) and Le Caer et al. (on infrared spectroscopy) illustrate alternative approaches. Others, not explicitly addressed, but key to... 

James R Wishart received a B.S. in Chemistry from the Massachusetts Institute of Technology in 1979 and a Ph.D. in Inorganic Chemistry from Stanford University in 1985 under the direction of Prof Henry Taube. After a postdoctoral appointment at Rutgers University, in 1987 he joined the Brookhaven National Laboratory Chemistry Department as a Staff Scientist in the Radiation Chemistry Group. He founded and presently supervises the BNL Laser-Electron Accelerator Facility for picosecond electron pulse radiolysis. His research interests include ionic liquids, radiation chemistry, electron transfer, and new technology and techniques for pulse radiolysis. He has authored over 90 papers and chapters, and is the co-editor of Advances in Chemistry Series o. 254, Photoehemistry and Radiation Chemistry. 

A simplified view of the early processes in electron solvation is given in Figure 7. Initially, electron pulse radiolysis was the main tool for the experimental study of the formation and dynamics of electrons in liquids (Chapter 2), first in the nanosecond time range in viscous alcohols [23], later in the picosecond time range [24,25]. Subsequently, laser techniques have achieved better time resolution than pulse radiolysis and femtosecond pump-probe laser experiments have led to observations of the electron solvation on the sub-picosecond to picosecond time scales. The pioneering studies of Migus et al. [26] in water showed that the solvation process is complete in a few hundreds of femtoseconds and hinted at the existence of short-lived precursors of the solvated electron, absorbing in the infrared spectral domain (Fig. 8). The electron solvation process could thus be depicted by sequential stepwise relaxation cascades, each of the successive considered species or... 

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