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The absorption spectra of the hydrated electron in 1.0 to 4.0 M LiCl or LiCl[O.sub.4] deuterated water solutions were measured by pulse radiolysis techniques from room temperature to 300 degree Celsius at a constant pressure of 25 MPa. The results indicated that when the temperature is increased and the density is decreased, the absorption spectrum of the electron in the presence of a lithium cation is shifted to lower energies.

Methyl viologen (1,1-dimethyl-4-4-bipyridinium dichloride) is used as a scavenger to estimate the radiolytic yields of water decomposition products from room temperature to 400 degree Celsius by pulse radiolysis method. {G(e(sub aq)(super -) + G(OH) + G(H)} is studied using a 0.5 mM MV(super 2+) solution in the presence of 10 mM NaCOOH up to 200 degree Celsius and in the presence of 0.2 M ethanol up to 400 degree Celsius.

The temperature dependence of the absorption spectrum of the formation and decay of dimer anion (SCN)(sub 2)(super dot-) is analysed in the temperature range of 25 to 400 degree Celsius. Analysis showed that the absorption peak shift to longer wavelength (red shift) with increase in temperature.

The spectral changes as well as the reaction kinetics of the transient species of 4,4'-bipyridyl (4,4'-bpy) are experimentally investigated by pulse radiolysis techniques up to 400 degree Celsius. The results show that the transient species such as OH adduct 4,4'-bpyOH., monoprotonated electron adduct 4,4'-bpyH. and doubly protonated electron adduct 4,4'-bpyH2+. have 15-20 nm blue shifts from room temperature to 400 degree Celsius.

γ-raysand pulse radiolysis of aqueous solutions of Ni2+ionsin the presence of polyacrylate (PA–) and 2-propanolleads to the formation of metastable species absorbingat 540 nm that are ascribed to “pink” oligomeric clustersof a few nickel atoms only. The molar absorption coefficient is evaluatedas ε540 nm= 3300 ± 300 L mol–1cm–1per Ni0atom. The successive stepsfrom the reduction of Ni2+into Ni+ions tothe formation of the pink clusters at 540 nm under conditions of complexationby PA–are investigated by pulse radiolysis. Theyield of the formation of pink clusters increases markedly with theirradiation dose rate, demonstrating the occurrence of the disproportionationof the [Ni+, PA–] complex after a singleelectron pulse. The reduction and nucleation mechanisms, includingrate constants, in competition with the back oxidation by protons,particularly at low dose rate, are discussed. [ABSTRACT FROM AUTHOR]

The absorption spectra of Br2•̵ and Br3̵ in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350 °C, respectively. Br2•̵ can be observed even in supercritical conditions, showing that this species could be used as a probe in pulse radiolysis at high temperature and even under supercritical conditions. The weak temperature effect on the absorption spectra of Br2•̵ and Br3̵ is because, in these two systems, the transition occurs between two valence states; for example, for Br2̵ we have 2Σu→2Σg transition. These valence transitions involve no difiuse final state. However, the absorption band of Br̵ undergoes an important red shift to longer wavelengths. We performed classical dynamics of hydrated Br̵ system at 20 and 300 °C under pressure of 25 MPa. The radial distribution functions (rdfs) show that the strong temperature increase (from 20 to 300 °C) does not change the radius of the solvent first shell. On the other hand, it shifts dramatically (by 1 Å) the second maximum of the Br-- O rdf and introduces much disorder. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br̵ at two temperatures and we compared the results with the experimental data. [ABSTRACT FROM AUTHOR]

Picosecond pulse radiolysis measurements using a pulse-probe method are performed to measure directly the time-dependent radiolytic yield of the OH(•) radical in pure water. The time-dependent absorbance of OH(•) radical at 263 nm is deduced from the observed signal by subtracting the contribution of the hydrated electron and that of the irradiated empty fused silica cell which presents also a transient absoption. The time-dependent radiolytic yield of OH(•) is obtained by assuming the yield of the hydrated electron at 20 ps equal to 4.2 × 10(-7) mol J(-1) and by assuming the values of the extinction coefficients of e(aq)(-) and OH(•) at 782 nm (ε(λ=782 nm) = 17025 M(-1) cm(-1)) and at 263 nm (ε(λ=263 nm) = 460 M(-1) cm(-1)), respectively. The value of the yield of OH(•) radical at 10 ps is found to be (4.80 ± 0.12) × 10(-7) mol J(-1).

The absorption spectra of Br(2)(•-) and Br(3)(-) in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350 °C, respectively. Br(2)(•-) can be observed even in supercritical conditions, showing that this species could be used as a probe in pulse radiolysis at high temperature and even under supercritical conditions. The weak temperature effect on the absorption spectra of Br(2)(•-) and Br(3)(-) is because, in these two systems, the transition occurs between two valence states; for example, for Br(2)(-) we have (2)Σ(u) → (2)Σ(g) transition. These valence transitions involve no diffuse final state. However, the absorption band of Br(-) undergoes an important red shift to longer wavelengths. We performed classical dynamics of hydrated Br(-) system at 20 and 300 °C under pressure of 25 MPa. The radial distribution functions (rdf's) show that the strong temperature increase (from 20 to 300 °C) does not change the radius of the solvent first shell. On the other hand, it shifts dramatically (by 1 Å) the second maximum of the Br-O rdf and introduces much disorder. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br(-) at two temperatures and we compared the results with the experimental data.

With a revisit of the absorption coefficient of the solvated electron in propane-1,2,3-triol, the temperature-dependent behavior of the absorption spectrum of solvated electron was studied from room temperature to 573 K by pulse radiolysis techniques. The change in the absorption spectrum of solvated electron in propane-1,2,3-triol observed by cooling down from a high temperature to 333 K is compared with that occurring during the electron solvation process at 333 K. The effect of the specific molecular structure of propane-1,2,3-triol compared to other alcohols is discussed.

The absorption spectra of the solvated electron in 1,2-ethanediol (12ED), 1,2-propanediol (12PD), and 1,3-propanediol (13PD) have been determined by nanosecond pulse radiolysis techniques. The maximum of the absorption band located at 570, 565, and 575 nm for these three solvents, respectively. With 4,4'-bipyridine (44Bpy) as a scavenger, the molar extinction coefficients at the absorption maximum of the solvated electron spectrum have been evaluated to be 900, 970, and 1000 mol-1 m2 for 12ED, 12PD, and 13PD, respectively. These values are two-thirds or three-fourths of the value usually reported in the literature. With these extinction coefficients, picosecond pulse radiolysis studies have allowed us to depict the radiolytic yield of the solvated electron in these solvents as a function of time from picosecond to microsecond. The radiolytic yield in these viscous solvents is found to be strongly different from that of water solution.

The reactions of OH* or SO4*- radicals with carboxymethyl chitin (CM-chitin) and its deacetylated product, carboxymethyl chitosan (CM-chitosan), were investigated in aqueous solutions using a laser photolysis technique. The rate constants of the reactions of OH* and SO4*- radicals with CM-chitosan are always higher than those for CM-chitin, indicating that the amino-group could increase the reactivity of carboxymethylated chitin derivatives. The rate of the reactions of CM-chitin and CM-chitosan with OH* radical was found to decrease at lower pH when polymers chains tend to the coiled conformation. In comparison, the rate constant of the reaction of SO4*- radicals with CM-chitin or CM-chitosan decreased with pH, indicating that CM-chitin or CM-chitosan has a higher reactivity with the SO4*- radical at low pH due to the protonation of the amino group.