On pulse radiolysis

In marked contrast there exists a volumnous literature on pulse radiolysis studies of nitric acid solutions (9). The NO3 radical has been identified as a major product although the mechanism of formation is still a matter of debate. While a number of reactions of this radical have been reported (10) there has evidently not been any pulse radiolysis studies of reactions with Pu ions. 

Aromatic nitro compounds are also prone to undergo one-electron reduction on pulse radiolysis. The behaviour of the radical cation so formed is dependent upon the type of... 

On pulse radiolysis using CO f (—2.0 V) to reduee PCu(II)Ru(III) (pH 7, 20 °C) the behavior observed is in both cases very similar [50]. The concentration of C02 was adjusted so that there was <20% reduction of modified protein. As far as can be ascertained, reduction efficiencies in the first stage are about the same, with reaction partitioned between the Cu(II) (72%) and the... 

In order to further probe the above route for electron transfer, there is a need to study derivatives modified at Tyr83. One such derivative in which the phenolic group of Tyr83 has been N02-modified has so far been prepared [139], On pulse radiolysis reduction with Cd to give the radical Tyr83NOj, fast electron transfer through to the Cu(II) is observed, k>10 s [140]. 

The solute benzene radical cation was formed on pulse radiolysis of an acidic aqueous solution of benzene. The transient optical absorption bands (A-max = 310, 350-500 nm) were assigned to the solute benzene radical cation which is formed on acid-catalysed dehydration of the OH adduct. The radical cation is able to undergo an electron-transfer reaction with Br and was found to be a strong electron oxidant. Pulse radiolysis has been used to study the complex reaction that follows electron addition to hydroxybenzophenones (HOBPs). The various radical species involved have been characterized spectrally and their p/fa values evaluated. The differences... 

Reaction Scheme of CMS Resists. The transient absorption spectrum shown in Figure 6 and observed for irradiated CMS films is mainly composed of two components as based on pulse radiolysis data of solid films of CMS and polystyrene, and CMS and polystyrene solutions in cyclohexane, chloroform, and carbon tetrachloride. An absorption with a maxima at 320 nm and 500 nm as due to the charge transfer radical-complex of the phenyl ring of CMS and chlorine atom (see Figure 14) and an absorption with maxima at 312 and 324 nm is due to benzyl type radicals (see Figure 11). 

Hayon447 to absorb in this UV region. Similar measurements have been made for a number derivatives of uracil (5,6-dihydro, 1-, 3-, and 6-methyl, 1,3-dimethyl-, and 5-aminouracil, orotic acid, barbituric and isobarbituric acids also see similar measurements448 on 5-bromouracil and its iV-methyl derivatives), thymine itself and its derivatives (5,6-dihydro, 2-methylthymine). In the case of cytosine, Hayon447 has very tentatively suggested that species 47 and 48 are obtained on pulse radiolysis of the solution at pH 5.5, and 49 at pH 13.3. 

Reprinted with permission from Dorfman, L. Man4 Matheson, M. S., Chapter on Pulse Radiolysis in Progress in Reaction Kinetics, Porter, G., ed., Pergamon Press, London 1965. 

The behavior of cationic intermediates produced in styrene and a-methyl-styrene in bulk remained a mystery for a long time. The problem was settled by Silverman et al. in 1983 by pulse radiolysis in the nanosecond time-domain [32]. On pulse radiolysis of deaerated bulk styrene, a weak, short-lived absorption due to the bonded dimer cation was observed at 450 nm, in addition to the intense radical band at 310 nm and very short-lived anion band at 400 nm (Fig. 4). (The lifetime of the anion was a few nanoseconds. The shorter lifetime of the radical anion compared with that observed previously may be due to the different purification procedures adopted in this experiment, where no special precautions were taken to remove water). The bonded dimer cation reacted with a neutral monomer with a rate constant of 106 mol-1 dm3s-1. This is in reasonable agreement with the propagation rate constant of radiation-induced cationic polymerization. 

Fig. 9. Transient absorption spectra observed at ambient temperature on pulse radiolysis of MTHF solution containing 5 base-m mol dm " 3 poly(4-vinylbiphenyl-co-l-vinylpyrene). The content of pyrenyl group is 0.15% against the total number of the side groups. (O) pulse end ( ) 0.2 ps after a pulse (T1) 1.4 ps after a pulse [60]...

In marked contrast there exists a volumnous literature on pulse radiolysis studies of nitric acid solutions ( ). The NO3 radical has been identified as a major product although the... 

Pulse Radiolysis A technique related to flash photolysis pulse radiolysis uses very short (nanosecond) intense pulses of ionizing radiation to generate transient high concentrations of reactive species. See Salmon, G. A. and Sykes, A.G., Pulse radiolysis, Methods Enzymol. 227, 522-534, 1993 Maleknia, S.D., Kieselar, J.G., and Downard, K.M., Hydroxyl radical probe of the surface of lysozyme by synchrotron radiolysis and mass spectrometry. Rapid Commun. Mass Spectrom. 16, 53-61, 2002 Nakuna, B.N., Sun, G., and Anderson, V.E., Hydroxyl radical oxidation of cytochrome c by aerobic radiolysis, Free Radic. Biol. Med. 37, 1203-1213, 2004 BataiUe, C., Baldacchino, G., Cosson, R.P. et al., Effect of pressure on pulse radiolysis reduction of proteins, Biochim. Biophys. Acta 1724, 432-439, 2005. 

Gawandi VB, Mohan H, Mittal JP. (2003) Investigations on the nature of the transient species formed on pulse radiolysis of a aqueous solution of 4-(methylthio)benzoic acid. Res Chem Intermed 29 51-62. 

BataiUea C, Baldacchinoa G, Cosson RP, Coppoc M, Trehenc C, Vignerona G, Renaulta JP, Pina S. (2005) Effect of pressure on pulse radiolysis reduction of proteins. Biochim Biophys Acta 1724 432 39. 

Therefore this present chapter is limited only to discussion on pulse radiolysis studies of promising compounds that exhibit potent biological activities for example, hydroxyl-flavonoids, resveratrol, curcumin, /3-carotene and cyclic nitroxides are reported here. 

In 1965, the first International Symposium on Pulse Radiolysis was held in Manchester and the scientific contributions and discussions were published in book form. One of these contributions [64] described what is probably the first determination, by means of pulse radiolysis, of rate constants for electron transfer from transient species, obtained from the reaction of Caq with various metal ions, and Mn04 these reactions were followed by monitoring of the disappearance of the absorbance of Mn04 [64] ... 

Comparison of the optical absorption curves shown in Fig. 5 reveals that solvated electrons are generated in alkali metal salt solutions during cathodic polarization. In fact, the particles that form during electrolysis are identical to those appearing under conditions for which the formation of solvated electrons is well proved, i.e., on dissolution of alkali metals and on pulse radiolysis of pure solvent and/or of the salt solutions. 

HMPT to the phosphonic amide derivative (35). The blue colour produced on pulse radiolysis of HMPT, initially thought to be due to solvated electrons. 

Direct assays for SOD have relied on pulse radiolysis (K12.M15), stopped-flow spectroscopy (M4,M17), rapid-flow electron paramagnetic resonance (EPR) (Bl,05, SI), polarographic techniques (R4), and nuclear magnetic resonance (NMR) spectroscopy (R3). 

The quantum beats method has been also applied for studying viscous squalane solutions [19], where highly mobile holes were found [32] in pulse radiolysis experiments. The rate constant of hole capture was determined from the slope to be 6.1x10 NT s", which confirms conclusion on the high mobility of holes in squalane. The rate constant of squalane hole decay was estimated from the intercept to be (8.3 2)xl0 s , which is also in fair agreement with experiments on pulse radiolysis [32]. 

Superoxide dismutation appears to occur via two sequential reactions which are each first-order in superoxide, based on pulsed radiolysis. Thus, the metal ion alternately accepts and donates an electron in conjunction with proton transfer. 

As for Fe-SOD and Cu,Zn-SOD, a two-step reaction in which both steps are first-order in 02 has been elucidated based on pulsed radiolysis. " A proton is taken up upon reduction, as in Fe-SOD and consistent with computations producing the following overall stoichiometry ... 

A review on pulse radiolysis contains references to a number of intriguing metal-metal electron-transfer reactions with relatively unfamiliar reagents such as Zn+, Cd+, and Ag . ... 

Extensive compilations of rate constants for the reactions of metal ions in unusual valency states and of inorganic free radicals in aqueous solution have appeared, as well as short reviews on pulse radiolysis studies in general chemistry and on complexes of metal ions in unstable oxidation stages. ... 

The Connections highlight on pulse radiolysis on page 402 used acetophenone as an example. Explain exactly how you anticipate this experiment was performed (you may need to consider issues described in Chapter 5). Why is the pK, of the resulting alcohol so much lower than a normal alcohol ... 

Following the decay of the radical-anion absorption, other secondary transient product spectra are observed (Figures 2a and 3). The principal features of these product spectra can be identified as the one-electron oxidation of tyrosine and tryptophan by comparison with spectra obtained on pulse radiolysis of solutions of the free amino-acids (6). The phenoxyl radical of tyrosine... 

As for the experiments with the radiation chemical technique, one of the present authors (Tagawa) presented the optical absorption spectra of both radical cation and anion of polysilanes and their pairing properties of both radical ions in his earliest work on pulse radiolysis (4), Tagawa and his co-workers reported that strong UV absorption bands due to the delocalized charge in the... 

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