Pulse Radiolysis Study Research Articles

Pulse radiolysis of thionicotinamide in aqueous solutions: formation of resonance stabilized species on one electron oxidation

Pulse radiolysis studies on thionicotinamide (TNA) have been carried out in aqueous solutions at pH 6.8 and 1. The initial species formed by OH radical reaction with TNA at pH 6.8 was found to react with the parent molecule to give a dimer radical species (λmax = 420-440 nm). Reaction of Br2-• radicals with TNA was found to give a transient species having λmax at 380 nm. This spectrum has been assigned to a resonance stabilized species with free electron delocalised over the -N-C-S bond. Reactions of OH and Cl22-• radicals with TNA at pH 1 were found to give identical transient species with λmax at 420 nm, which decayed by first-order kinetics at a rate of about 8.0 × 103 s-1. This species is suggested to be the protonated form of the resonance-stabilized species formed at pH 6.8 in the reaction of Br2-• with TNA. The rate constant for the reaction was 4 × 109 dm3 mol-1 s-1. Semi-reduced species formed by the reaction of e-aq with TNA (k = 1.6 × 1010 dm3 mol-1 s-1) was found to be a good reductant which could transfer electron to methyl viologen. CO2-• radicals also reacted with TNA to give a reducing species. Although, the absorption peaks in the two cases were at the same wavelengths viz. 380 and 480 nm, the ratios of the peak heights were different suggesting the formation of different species. Hydrogen atoms and (CH3)2C•OH radicals were found to transfer an electron to TNA at pH 1, as seen by quantitative electron transfer to methyl viologen from the transient species.

A spectroscopic and pulse radiolysis study of allopurinol and its copper complex

Allopurinol (ALP), an anti-hyperuricemic drug, was investigated in the absence and in the presence of Cu(II) ions by vibrational spectroscopy and pulse radiolysis technique in order to obtain some elucidation on the mechanism of its beneficial effect against oxygen free radical-mediated damage. ALP is suggested to give protection to living organisms both by metal chelation and direct scavenging of free radicals. The Raman and IR spectra have been useful to assess the relevant interactions of ALP with Cu(II) ions, which play an important role in the metal catalysed generation of reactive oxygen species. A proposal of the complex structure was performed; the predominant species seems to be a monomeric complex where ALP interacts with the metal by one nitrogen atom of the five-membered ring and the CO group. The pulse radiolysis data have given information on the behaviour of ALP towards radiation-induced radicals. ALP appears to be a good scavenger of OH, giving rise to intermediate transients, namely resonance-stabilised phenoxyl radicals. Also in the presence of Cu(II) ions, ALP reacts fast towards OH radicals.

Pulse radiolysis study on the free radical scavenging activities of puerarin

The free radical scavenging activities of puerarin towards nitrogen dioxide radicals (NO2.), nitric oxide radicals (NO.) and hydroxyl radicals (OH.) were investigated by pulse radiolysis. Puerarin reacted With NO2. or NO. to form puerarin-4-O-. with the absorption maximum at 340 nm, but reacted with OH. to form at least three transient species including puerarin-2-O-. puerarin-4-O-. and [puerarin-OH](.) with a broad absorption spectrum band (300-750 nm). In addition, the reaction rate constants of puerarin reacting with NO2., NO. and OH. were determined as 2.6X 10(8), 1.7 X 10(8) and 3.9 X 10(9) L . mol(-1) . s(-1), respectively.

The role of radiolytically generated species in radiation-induced polymerization of vinylbenzyltrimethylammonium chloride (VBT) in aqueous solution: steady-state and pulse radiolysis study.

Radiation-induced polymerization of vinylbenzyltrimethylammonium chloride (VBT) in aqueous solution has been investigated by steady-state and pulse radiolysis techniques. The effects of dose, dose rate, monomer concentration, pH, and ambient conditions on steady state polymerization were investigated. The reactions of primary radicals of water radiolysis, such as OH radical, e(-)aq, and H atom, were studied. The reactions of other chemically active species such as O*-, oxidizing radicals such as N3*, Cl2(*-), Br(2*), SO4(*-), and a reducing specie such as CO2(*-) with VBT were also investigated. The reaction of VBT with OH radical and H atom were investigated by formation kinetics and by competition kinetics. The rate constant values for the reaction of OH radical with VBT were 4.7 x 10(9) dm3 mol(-1) s(-1) and 1.7 x 10(10) dm3 mol(-1) s(-1) by formation kinetics and by competition kinetics, respectively. The results indicate that OH radicals undergo electron transfer reactions (resulting in a radical cation) and addition reactions. The hydrated electron reacts with VBT with a rate constant of 1.9 x 10(10) dm3 mol(-1) s(-1) to form an anion. At pH approximately 1, H atom reaction with VBT is diffusion controlled with a rate constant of 5.1 x 10(9) dm3 mol(-1) s(-1) as determined by formation kinetics and 1.7 x 10(10) dm3 mol(-1) s(-1) as determined by competition kinetics. VBT radical anion reacts with VBT at a rate that is almost twice the rate at which VBT radical cation reacts with VBT, indicating anionic initiation of the polymerization of VBT. VBT undergoes very fast steady-state polymerization and dose rate; the presence of efficient radical quenchers such as oxygen and concentration of VBT in the aqueous solution affects the extent of polymerization. Typically, a dose of 4 kGy is sufficient to achieve 80-85% polymerization. The monomer solution shows a drastic increase in the viscosity of the solution, which finally gels to a soft rubbery mass.

The reactions of cytidine and 2'-deoxycytidine with SO4.- revisited. Pulse radiolysis and product studies.

The reactions of SO4.- with 2'-deoxycytidine 1a and cytidine 1b lead to very different intermediates (base radicals with 1a, sugar radicals with 1b). The present study provides spectral and kinetic data for the various intermediates by pulse radiolysis as well as information on final product yields (free cytosine). Taking these and literature data into account allows us to substantiate but also modify in essential aspects the current mechanistic concept (H. Catterall, M. J. Davies and B. C. Gilbert, J. Chem. Soc., Perkin Trans. 2, 1992, 1379). SO4.- radicals have been generated radiolytically in the reaction of peroxodisulfate with the hydrated electron (and the H. atom). In the reaction of SO4.- with 1a (k = 1.6 x 10(9) dm3 mol-1 s-1), a transient (lambda max = 400 nm, shifted to 450 nm at pH 3) is observed. This absorption is due to two intermediates. The major component (lambda max approximately 385 nm) does not react with O2 and has been attributed to an N-centered radical 4a formed upon sulfate release and deprotonation at nitrogen. The minor component, rapidly wiped out by O2, must be due to C-centered OH-adduct radical(s) 6a and/or 7a suggested to be formed by a water-induced nucleophilic replacement. These radicals decay by second-order kinetics. Free cytosine is only formed in low yields (G = 0.14 x 10(-7) mol J-1 upon electron-beam irradiation). In contrast, 1b gives rise to an intermediate absorbing at lambda max = 530 nm (shifted to 600 nm in acid solution) which rapidly decays (k = 6 x 10(4) s-1). In the presence of O2, the decay is much faster (k approximately 1.3 x 10(9) dm3 mol-1 s-1) indicating that this species must be a C-centered radical. This has been attributed to the C(5)-yl radical 8 formed upon the reaction of the C(2')-OH group with the cytidine SO4(.-)-adduct radical 2b. This reaction competes very effectively with the corresponding reaction of water and the release of sulfate and a proton generating the N-centered radical. Upon the decay of 8, sugar radical 11 is formed with the release of cytosine. The latter is formed with a G value of 2.8 x 10(-7) mol J-1 (85% of primary SO4.-) at high dose rates (electron beam irradiation). At low dose rates (gamma-radiolysis) its yield is increased to 7 x 10(-7) mol J-1 due to a chain reaction involving peroxodisulfate and reducing free radicals. Phosphate buffer prevents the formation of the sugar radical at the SO4(.-)-adduct stage by enhancing the rate of sulfate release by deprotonation of 2b and also by speeding up the decay of the C(5)-yl radical into another (base) radical. Cytosine release in cytidine is mechanistically related to strand breakage in poly(C). Literature data on the effect of dioxygen on strand breakage yields in poly(C) induced by SO4.- (suppressed) and upon photoionisation (unaltered) lead us to conclude that in poly(C) and also in the present system free radical cations are not involved to a major extent. This conclusion modifies an essential aspect of the current mechanistic concept.

Effect of solvent viscosity, polarity and pH on the charge transfer between tryptophan radical and tyrosine in bovine serum albumin: a pulse radiolysis study

The effect of viscosity, solvent polarity and pH of the medium on the reaction of a protein, bovine serum albumin (BSA), with organohalo-peroxyl radical in aqueous solution has been studied using pulse radiolysis technique. Unlike in dilute aqueous solution, electron transfer from tyrosine to tryptophan radical in BSA has been clearly observed at a viscosity of 7.7 centiPoise (cP). The oxidation of BSA, tryptophan and tyrosine in different media has also been compared with those taking place in dilute aqueous solution. The effect of solvent characteristics on the observed charge transfer has been discussed.

Direct optical observation of the formation of some aliphatic alcohol radicals. A pulse radiolysis study

The kinetics of the reactions of hydroxyl radicals and hydrogen atoms with some aliphatic alcohols in aqueous solutions were studied using pulse radiolysis. Based on the increase in optical absorption in the UV region, the rate constants for the reaction of hydroxyl radicals and hydrogen atoms with methanol, ethanol, 2-propanol ort-butyl alcohol were determined to be 9.0 × 108, 2.2 × 109, 2.0 × 109,6.2×l08 and 1.1 × 106, 1.8 × 107, 5.3 × 107, 2.3 × 105 dm3 mol−1 s−1 respectively. The bimolecular decay rate constants for the alcohol radicals produced in methanol and ethanol were evaluated to be 2.4 × 109 and 1.5 × 109 dm3 mol−1s−1. The values observed are in fairly good agreement with those reported earlier.

Effect of electron-withdrawing power of the substituted group on•OH radical reaction with substituted aryl sulphides: A pulse radiolysis study

In neutral aqueous solution of (phenylthio)acetic acid, hydroxyl radical is observed to react with a bimolecular rate constant of 7.2 × 10-1 dm3 mol−s− and the transient absorption bands are assigned to•OH radical addition to benzene and sulphur with a rough estimated values of 50 and 40% respectively. The reaction of the•OH radical with diphenyl sulphide (k = 4.3 × 108 dm3 mol−1 s−1) is observed to take place with formation of solute radical cation, OH-adduct at sulphur and benzene with estimated values of about 12, 28 and 60% respectively. The transient absorption bands observed on reaction of•OH radical, in neutral aqueous solution of 4-(methylthio)phenyl acetic acid, are assigned to solute radical cation (λmax = 550 and 730 nm), OH-adduct at sulphur (λmax = 360 nm) and addition at benzene ring (λmax = 320 nm). The fraction of•OH radical reacting to form solute radical cation is observed to depend on the electron-withdrawing power of substituted group. In acidic solutions, depending on the concentration of acid and electron-withdrawing power, solute radical cation is the only transient species formed on reaction of•OH radical with the sulphides studied.

Reduction of Substituted Benzenediazonium Salts by Solvated Electrons in Aqueous Neutral Solution Studied by Pulse Radiolysis

A pulse radiolysis study of six parasubstituted benzenediazonium salts, X−C6H4N2+ [X = COOC2H5, F, H, CH3, OCH3, and N(CH3)2], has been carried out in neutral aqueous solutions, where the principal reductant is the solvated electron. In the first step, the solvated electron reduces the diazonium salts to the corresponding diazenyl radicals, X−C6H4N2•, in a diffusion-controlled process. On a short time scale, X−C6H4N2• is either involved in an equilibrium reaction with the parent diazonium salt (K > 100 M-1) in which a (X−C6H4)2N4•+ adduct is formed or decays to the aryl radical, X−C6H4•, through the expulsion of dinitrogen. Simulation of this kinetic scheme allows us to make a rough determination of the rate constants involved. The rate constants for the formation of the adducts are in the range (0.7−1.9) × 107 M-1 s-1, whereas the fragmentation rate constants are in the range (0.4−4.0) × 105 s-1. The aryl radicals subsequently attack the diazonium salts mainly at the terminal nitrogen atom with rate cons...

Kinetic and spectral properties of rhodamine 6G free radicals: a pulse radiolysis study

Using the pulse radiolysis technique Br 2 − has been shown to react with the laser dye, rhodamine 6G (RhH +) to produce cation radicals. At pH 4, the species designated RhH 2 + is produced which was shown to deprotonate with a p K a of 5.7 yielding Rh +. Both forms of the radical have characteristic transient difference absorption spectra with distinct maxima at 470 nm. The cation radicals are relatively long-lived and can be observed for up to 1 s after the pulse. At the end of the reaction(s) of Rh +, significant increases in absorption relative to the ground state area were observed in the dye laser output region, 555–620 nm. Oxygen had no effect on the decay of these radicals; however, it was demonstrated that O 2 − could regenerate the dye ground state in a redox process. At high concentrations of rhodamine 6G, it appears that only monomeric cation radicals are formed on reaction with Br 2 −, suggesting that any dimer cation radicals formed initially are short-lived ( k[dissociation]>5×10 6 s −1). The relevance of cation radical formation to the efficiency and photostability of rhodamine dye laser systems in both liquid and solid state is discussed. It is proposed that the formation of such radicals, particularly in the solid state, may account for the loss of efficiency and photostability and so provide an alternative mechanism to one involving the dye triplet state.

A pulse radiolysis study of coumarin and its derivatives

The kinetics and the transient absorption spectra from the reactions of OH, O −, e aq − and SO 4 − radicals with coumarin, 4-methyl-7-hydroxycoumarin, 7-methoxycoumarin and 6,7-dimethoxycoumarin in aqueous solutions were studied by pulse radiolysis with optical detection. The second-order rate constants for the reaction of the OH radical with coumarin was found to be 6.4×10 9 dm 3 mol −1 s −1 and the introduction of different substituents to coumarin did not have any significant effect on the rates. The rate constants for the reaction of the hydrated electron, however, decreased with the introduction of the electron donating groups. The transient absorption spectra of the OH adducts of coumarin and its derivatives have λ max at 360–370 and 425–460 nm. In the case of 4-methyl-7-hydroxycoumarin, the OH adduct undergoes dehydration leading to phenoxyl radical. The radical cation of coumarin formed by electron transfer in the SO 4 − reaction is hydrolysed to yield the OH adducts. The radical cation is stabilised in methoxy derivatives or undergoes deprotonation to give phenoxyl radical in 4-methyl-7-hydroxycoumarin. The initially formed radical anion of coumarin and its derivatives formed in the reaction of the hydrated electron is protonated very fast ( k≥10 7 s −1). The neutral electron adduct of coumarin ( λ max=360 nm) is finally transformed by 1,2-H shift ( k=2.7×10 4 s −1) into a thermodynamically more stable oxygen centred radical.

Pulse Radiolysis Study on Reactions of a Hydrated Electron with Europium(III)−Aminopolycarboxylate Complexes in Aqueous Perchlorate Media

Pulse radiolysis of 1:1 complexes of europium(III)-aminopolycarboxylates was studied in aqueous perchlorate solutions to understand relations of the reduction rate of Eu(III) with hydration state and stability of the complex. The rate constant for the reaction of a hydrated electron (e aq - ) with the complex was determined in the temperature range of 278.15 to 333.15 K and the ionic strength range of 0.05 to 1.0 mol kg -1 . The rate constant was linearly related not only with the residual hydration number of the complex representing the hydration state but also with the stability constant and redox potential as equilibrium constants. The reaction of eaq - with the complex was described by diffusive encounter and successive electron-transfer processes between eaq - and the complex. Gibbs free energy, enthalpy, and entropy of activation for the reaction were obtained from the effect of temperature on the rate constant, and the entropy term was found to be a dominant factor for the electron-transfer process after the diffusion process. These indicated that the entropy term, reflecting ionic interaction of Eu(III) -carboxylate groups and dehydration of aquo Eu(III) ion on the complexation, caused the difference in the rate constant between the complexes, and linear correlation between the rate constant and hydration number. The effect of ionic strength on the rate constant was examined by

Repair of amino acid radicals of apolipoprotein B100 of low-density lipoproteins by flavonoids. A pulse radiolysis study with quercetin and rutin.

Selective oxidative damage to apolipoprotein B in LDL can be effected radiolytically by (*)Br(2)(-) radicals. Twenty-seven Trp residues constitute major primary sites of oxidation, but two-thirds of oxidized Trps ((*)Trp) that are formed are repaired by intramolecular electron transfer from Tyr residues with formation of phenoxyl radicals (TyrO(*)). Analysis of (*)Trp and TyrO(*) transient absorbance changes suggests that other apolipoprotein B residues, probably Cys, are oxidized. LDL-bound quercetin can efficiently repair this damage. Absorption studies show that a LDL particle has the capacity to bind approximately 10 quercetin molecules through interaction with apolipoprotein B. The repair occurs by intramolecular electron transfer characterized by a rate constant of 2 x 10(3) s(-)(1). In contrast, rutin, a related flavonoid which does not bind to LDL, cannot repair oxidized apolipoprotein B. Urate is a hydrophilic plasma antioxidant which displays synergistic antioxidant properties with flavonoids. Urate radicals produced by (*)Br(2)(-) can also be repaired by LDL-bound quercetin. This repair occurs with a reaction rate constant of 6.8 x 10(7) M(-)(1) s(-)(1). Comparison with previous studies conducted with human serum albumin-bound quercetin suggests that quercetin analogues tailored to be carried preferentially by lipoproteins might be more powerful plasma antioxidants than natural quercetin carried by serum albumin.

One-electron reduction of 1,2-dihydroxy-9,10-anthraquinone and some of its transition metal complexes in aqueous solution and in aqueous isopropanol–acetone-mixed solvent: a steady-state and pulse radiolysis study

One-electron reduction of 1,2-dihydroxy-9,10-anthraquinone (DHA) and its complexes with Cu(II), Ni(II) and Fe(III), by acetone ketyl radical, (CH 3) 2C·OH, was carried out in aqueous solution and in aqueous isopropanol acetone mixed solvent using both steady-state gamma radiolysis and pulse radiolysis techniques. The rate constants for the reduction of DHA at different pH values by the ketyl radical are in the order of ∼10 9 dm 3 mol −1 s −1, whereas those for the metal complexes are comparatively less. These rate constants are, however, in conformity with the one-electron reduction potentials of the ligand in free DHA and in its metal complexes. Decay kinetics of the one-electron reduced semiquinones of the free ligand and its metal complexes suggest disproportionation of the semiquinone in the case of the free ligand and intermolecular electron transfer from the co-ordinated semiquinone radical to the metal centre in the case of the metal complexes.

Mechanisms of flavonoid repair reactions with amino acid radicals in models of biological systems: a pulse radiolysis study in micelles and human serum albumin

Neutral tryptophan ( •Trp) and tyrosine (TyrO •) radicals are repaired by certain flavonoids in buffer, in micelles and in human serum albumin (HSA) with corresponding formation of semioxidized flavonoid radicals. In deaerated buffer, •Trp but not TyrO • radicals react with catechin. In micelles, quercetin and rutin repair both •Trp and TyrO • radicals. In addition to amino acid reactivity, microenvironmental factors and nature of the flavonoids govern this repair. Electron transfer efficiencies from quercetin to negatively charged •Trp radicals are 100% in the micellar pseudophases of positively charged cetyltrimethylammonium bromide, (CTAB), and neutral Triton X100 (TX100), but 55% in negatively charged sodium dodecyl sulfate (SDS). In oxygen-saturated CTAB micelles, quercetin also reacts with the superoxide radical anion. When bound to domain IIA of HSA, quercetin repairs, by intra- or intermolecular encounter, less than 20% of oxidative damage to HSA. Quercetin can also repair freely circulating oxidized molecules with repair efficiencies falling to 7% for oxidized Trp, Tyr and α-MSH and to less than 2% for urate radical. This limited effectiveness is attributed both to the inaccessibility of bound quercetin and rutin toward radicals of circulating molecules and to the diffusion-controlled recombination of these radicals.

The mediation of veratryl alcohol in oxidations promoted by lignin peroxidase: the lifetime of veratryl alcohol radical cation

The kinetics of decay of veratryl alcohol radical cation, generated by cerium(IV) ammonium nitrate induced oxidation of veratryl alcohol, have been followed spectrophotometrically in a stopped-flow apparatus. In acidic aqueous acetonitrile the radical cation was found to decay by a first-order process, due to deprotonation from the α-carbon leading to an α-hydroxybenzyl radical with the rate constant of 17.1±0.5 s −1 . This value is in full agreement with those obtained by pulse radiolysis studies but much lower than the value (1.2×10 3 s −1) indirectly determined by EPR experiments. The implications of these results with respect to the possible role of veratryl alcohol as a mediator in the oxidative biodegradation of lignin catalysed by lignin peroxidase are discussed.

A pulse radiolysis study of the oxidation of Br– by Cl2˙– in aqueous solution: formation and properties of ClBr˙–

The oxidation of Br− by Cl2˙− is investigated by pulse radiolysis in aqueous solutions of NaCl and NaBr. Depending on the ratio of the concentration of Br− to Cl−, the main product being observed is either Cl2˙−, ClBr˙− or Br2˙−. The mixed radical anion ClBr˙− exhibits a broad absorption band at 350 nm with e350 = 9300 dm3 mol−1 cm−1. The rate constants of the equilibrium Cl2˙− + Br− ⇌ ClBr˙− + Cl− are determined to be kf = 4 × 109 and kb = 1.1 × 102 dm3 mol−1 s−1.

Mechanisms of flavonoid repair reactions with amino acid radicals in models of biological systems: a pulse radiolysis study in micelles and human serum albumin

Neutral tryptophan ( •Trp) and tyrosine (TyrO •) radicals are repaired by certain flavonoids in buffer, in micelles and in human serum albumin (HSA) with corresponding formation of semioxidized flavonoid radicals. In deaerated buffer, •Trp but not TyrO • radicals react with catechin. In micelles, quercetin and rutin repair both •Trp and TyrO • radicals. In addition to amino acid reactivity, microenvironmental factors and nature of the flavonoids govern this repair. Electron transfer efficiencies from quercetin to negatively charged •Trp radicals are 100% in the micellar pseudophases of positively charged cetyltrimethylammonium bromide, (CTAB), and neutral Triton X100 (TX100), but 55% in negatively charged sodium dodecyl sulfate (SDS). In oxygen-saturated CTAB micelles, quercetin also reacts with the superoxide radical anion. When bound to domain IIA of HSA, quercetin repairs, by intra- or intermolecular encounter, less than 20% of oxidative damage to HSA. Quercetin can also repair freely circulating oxidized molecules with repair efficiencies falling to 7% for oxidized •Trp, Tyr and α-MSH and to less than 2% for urate radical. This limited effectiveness is attributed both to the inaccessibility of bound quercetin and rutin toward radicals of circulating molecules and to the diffusion-controlled recombination of these radicals.

A pulse radiolysis study of the rate of ligand dissociation from mixed ligand cobalt(ii) complexes

The reduction and subsequent reactions of the series of mixed ligand cobalt(III) complex cations, [Co(bipy)3]3+, [Co(phen)3]3+, [Co(en)3]3+, [Co(en)2(bipy)]3+, [Co(en)2(phen)]3+, [Co(en)2(5-NO2-phen)]3+, [Co(en)2(DPPZ)]3+, [Co(bipy)2(NH3)2]3+, [Co(bipy)(NH3)4]3+, [Co(phen)2(NH3)2](ClO4)3]3+ and [Co(phen)(NH3)4]3+, (where bipy is 2,2′-bipyridine, phen is 1,10-phenanthroline, en is ethylenediamine, 5-NO2-phen is 5-nitro-1,10-phenanthroline and DPPZ is dipyrido[3,2-a:2′,3′-c]phenazine) have been studied using pulse radiolysis. The crystal structures of the mixed ligand complexes [Co(bipy)2(NH3)2](ClO4)3, [Co(bipy)(NH3)4]Cl0.5(ClO4)2.5, [Co(phen)2(NH3)2](ClO4)3 and [Co(phen)(NH3)4](ClO4)3, have been determined. The mechanism of reduction of the cobalt(III) centre by e−aq has been found to vary depending upon the nature of the ligands present in the complex. When an aromatic ligand is present the formation of a coordinated ligand radical is observed. This decays via intramolecular electron transfer to produce the cobalt(II) complex. The rate constants for the intramolecular electron transfer processes are of the order of 103–104 s−1. The rates of ligand dissociation of bidentate ligands from the resulting cobalt(II) complexes have been determined. The relative rates of the dissociation of the first ligand from the complexes is found to be dependent upon the identity of the ligand and is related to the ligand structure. For the dissociation of the same ligand from related complexes, the electronic structure of the complex becomes a factor.

Dynamics of the blue shift of e tr− optical absorption spectra in ethanol–water glasses

The results of the pulse radiolysis study of ethanol containing water in the concentration range 0.8–20.56 mol% at temperatures ranging between 30 and 95 K are reported. In the presence of water, starting from ca. 3 ms after the pulse, the acceleration of the blue shift of the maximum of trapped electron spectrum takes place. It is suggested that this phenomenon, occurring at the lowest investigated temperatures (30, 50 K) is due to the structural changes in the EtOH–H 2O system.