The yield and extinction coefficient of the solvated electron in methanol: pulse radiolysis of nitrobenzene and tetranitromethane solutions

1977 ◽  
Vol 55 (11) ◽  
pp. 2030-2043 ◽  
Author(s):  
David W. Johnson ◽  
G. Arthur Salmon
Keyword(s):  
Pulse Radiolysis ◽  
Optical Pulse ◽  
Basic Solution ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Extinction Coefficients ◽  
Hydroxymethyl Radical ◽  
Direct Measurements ◽  
Wide Range ◽  
Basic Solutions

The radical anion [Formula: see text] NB−, which has a strong absorption spectrum from 250–500 nm, is formed by reaction of nitrobenzene with solvated electrons, es−, and hydroxymethyl radical anions, •CO2O−, with k1 = (1.92 ± 0.35) × 1010 M−1 s−1 and k2 = (1.03 ± 0.02) × 1010 M−1 s−1.[Formula: see text]Gελ is constant for NB− over a wide range of nitrobenzene concentrations in basic solution. By assuming that the yields of scavengeable radicals are the same in neutral and basic solutions we obtain ε(NB−)300 nm = (1.66 ± 0.02) × 104 M−1 cm−1. This value is used to evaluate the yield of es− scavengeable by dilute solutions of solutes as G(es−)esc = 1.20 ± 0.03. Extinction coefficients of es−, hydroxymethyl radicals, •CH2OH, and •CO2O− and the oscillator strength of the es− absorption are calculated.The yields of es− determined by previous workers are discussed in terms of dry, damp, geminate, free, spur, and escaped electrons. A model is constructed in terms of damp, spur, and escaped electrons which compares favourably with experimental scavenging results and direct measurements by optical pulse radiolysis.

Pulse Radiolysis of Alkali Metal Solutions in Ethylamine

1973 ◽  
Vol 51 (17) ◽  
pp. 2975-2986 ◽  
Author(s):  
J. W. Fletcher ◽  
W. A. Seddon ◽  
F. C. Sopchyshyn
Keyword(s):  
Alkali Metal ◽  
Pulse Radiolysis ◽  
Electron Pair ◽  
Equilibrium Constants ◽  
Distinct Species ◽  
Complexing Agents ◽  
Crown Compounds ◽  
Solvated Electron ◽  
Sodium Potassium ◽  
Extinction Coefficients

Pulse radiolysis of solutions of alkali metal ethylamides in ethylamine shows the formation of three distinct species; the solvated electron es−, the alkali metal anion M−, and a species considered to be the cation–electron pair with stoichiometry M. The three species coexist in equilibrium in accord with the equations[Formula: see text]Studies of these solutions as a function of temperature, alkali metal concentration, and added complexing agents ("crown" compounds) show that es− and M have distinct absorption spectra with the former having a maximum ≥ 1800 nm. The latter exhibit maxima at 1400 nm for Na and K, ~1400 nm for Cs, and 1600–1700 nm for Li. The corresponding M− species were observed in sodium, potassium, and cesium solutions with absorption maxima at 680, 890, and 1100 nm, respectively.Rate and equilibrium constants for the formation of M and M− vary markedly with the nature of the alkali metal. Estimates for these constants along with the extinction coefficients for the various species are summarized and compared with data obtained in alkali metal solutions.

The effect of temperature on the optical spectra and the yields of solvated electrons and ion-pairs in amines

1978 ◽  
Vol 56 (6) ◽  
pp. 839-843 ◽  
Author(s):  
William Arthur Seddon ◽  
John Wallace Fletcher ◽  
Fred Charles Sopchyshyn
Keyword(s):  
Ion Pairs ◽  
Solvent Polarity ◽  
Solute Concentration ◽  
Ion Pair ◽  
Effect Of Temperature ◽  
Gradual Transition ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Extinction Coefficients ◽  
Yield Formula

Optical absorption spectra for the solvated electron, es−, and ion-pairs, (Na+, es−), have been observed in methylamine (MA), ethylamine (EA), and isopropylamine (IPA), at temperatures ranging from 184 to 338 K. Changes in the (Na+, es−) spectra, relative to es−, are consistent with a gradual transition in the ion-pair structure toward a more 'electron-like' entity with decreasing temperature and increasing solvent polarity. Extinction coefficients, εmax(es−) = 3.3 ± 0.2, 3.2 ± 0.5, and 3.2 ± 0.5 × 104 M−1 cm−1 in MA, EA, and IPA respectively. Corresponding values for the ion-pairs, εmax(Na+, es−) = 2.5 ± 0.2, 2.1 ± 0.2, and 1.9 ± 0.2 × 104 M−1 cm−1.In EA and IPA, the yield [Formula: see text] (molecules/100 eV) shows a marked solute concentration dependence. This is consistent with an empirical scavenging model from which the escaped solvated G(es−)esc and spur G(es−)spur electrons are estimated as G(es−)esc = 0.5 and 0.4, G(es−)spur = 1.8 and 1.4, giving G(es−)total = 2.3 and 1.8 in EA and IPA, respectively. In MA, [Formula: see text] = G(es−)esc = 2.25 ± 0.2, independent of solute concentration.

Yield and properties of solvated electrons created by the γ radiolysis of hexamethylphosphorotriamide

1977 ◽  
Vol 55 (11) ◽  
pp. 1832-1835 ◽  
Author(s):  
M. C. Lebas ◽  
J. Sutton ◽  
A. M. Koulkes-Pujo
Keyword(s):  
Pulse Radiolysis ◽  
Total Yield ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Γ Rays

According to various authors, the value of the yield of the solvated electron in the pulse radiolysis of hexamethylphosphorotriamide (HMPT) varies from 1.2 to 2.4 and increases to 4.2 or 3.1 in the presence of NaBr. We exposed this compound to γ rays after purification and saturation with N2O. N2 was formed with a yield G(N2) = 4.4 ± 0.4. After elimination of a certain number of processes which might also lead to N2 formation, it was concluded that this G(N2) corresponds to the total yield of electrons. This value was confirmed by measuring G(Br−) obtained by radiolysis of HMPT with p-bromophenol as a scavenger. The yield of N2 remains constant whenever solutes generally known as good electron scavengers are added (H+, CH3COCH3, NO3−). An interpretation of the results leads to the suggestion of the formation of a dielectron in this medium.

Primary mechanisms in the radiolysis of amines: pulse and γ-radiolysis of neutral and acidic ethylamine, n-propylamine and ethylenediamine

1979 ◽  
Vol 57 (15) ◽  
pp. 2013-2021 ◽  
Author(s):  
J. A. Delaire ◽  
J. R. Bazouin
Keyword(s):  
Allyl Alcohol ◽  
Molecular Hydrogen ◽  
Pulse Radiolysis ◽  
Solvated Electron ◽  
Infrared Band ◽  
Solvated Electrons ◽  
Upper Limits ◽  
Transient Spectra ◽  
Alkyl Ammonium

The transient spectra in pure ethylamine (EA), n-propylamine (nPA), and ethylenediamine (EDA) show, besides the visible and infrared band associated with the solvated electron, e−s, a small ultraviolet band attributed to oxidizing radicals. Upper limits for the recombination rate constants k of e−s with the acidic cation are 1.5 × 1012 L mol−1 and 3.5 × 1012 L mol−1s−1 in EA and nPA respectively, and k = 2 × 1010 L mol−1 s−1 in EDA. The yield of e−s at 3 ns (G(e−s)3ns = 1.5, 1.2, and 3.1 molecules/100 eV in EA, nPA, and EDA respectively) has been deduced by biphenyl scavenging. The yield of molecular hydrogen after γ-radiolysis G0(H2) = 5.7 and 3.6 in pure nPA and EDA respectively. The effect of solutes, such as biphenyl, alkyl-ammonium chloride, and allyl alcohol, on G(H2) is interpreted in terms of scavenging of e−s and/or H atoms. From the pulse-radiolysis determination of G(e−s), we deduce [Formula: see text] in nPA.Finally, the decay of solvated electrons seems to occur only via recombination with the cation in EA and nPA, but in EDA there is a competition between this reaction and reaction with oxidizing radicals.

Pulse Radiolysis of Alkali Metal Solutions in Methylamine

1975 ◽  
Vol 53 (23) ◽  
pp. 3571-3579 ◽  
Author(s):  
John Wallace Fletcher ◽  
William Arthur Seddon ◽  
John Joseph Jevcak ◽  
Fred Charles Sopchyshyn
Keyword(s):  
Reaction Mechanism ◽  
Alkali Metal ◽  
Reaction Kinetics ◽  
Pulse Radiolysis ◽  
Ion Pairs ◽  
Solvated Electrons ◽  
Extinction Coefficients ◽  
Ion Species ◽  
Triple Ion ◽  
Metal Anions

Pulse radiolysis studies of solutions of alkali metal methylamides (CH3NHM) in methylamine indicate the formation of solvated electrons, es−, ion-pairs (M+, es−), and alkali metal anions M−. This paper compares the spectra, extinction coefficients, and yields of es−, Li, Na, K, and Cs species, with those observed previously in other solvents. The overall reaction kinetics are complex and, in CH3NHNa/NaI solutions, suggest the formation of a higher aggregate or triple ion species (Na22+, es−). A reaction mechanism, quantitatively consistent with experiment, is presented and discussed in detail for solutions containing Na+.

Pulse Radiolysis of Liquid Methylamine, Ethylamine, and Ammonia: The Yield of Solvated Electrons

1974 ◽  
Vol 52 (18) ◽  
pp. 3269-3273 ◽  
Author(s):  
William Arthur Seddon ◽  
John Wallace Fletcher ◽  
Fred Charles Sopchyshyn ◽  
John Jevcak
Keyword(s):  
Pulse Radiolysis ◽  
Basic Solution ◽  
Solvated Electrons

Yields of solvated electrons, [Formula: see text], have been measured in both the pure and basic solvents using biphenyl and pyrene as electron scavengers. In pure methylamine and ethylamine [Formula: see text]and 1.84 ± 0.1, respectively. However in basic solution these yields more than double giving [Formula: see text]. In liquid NH3 and ND3 at −15 °C, [Formula: see text] and 3.6 ± 0.2, respectively. The latter yields seem independent of base and temperature from −15 to −50 °C. Comparisons with previous work are discussed.

Temperature and density effects on the absorption maximum of solvated electrons in sub- and super-critical methanol

2010 ◽  
Vol 88 (10) ◽  
pp. 1026-1033 ◽  
Author(s):  
Y. Yan ◽  
M. Lin ◽  
Y. Katsumura ◽  
Y. Muroya ◽  
S. Yamashita ◽  
...  
Keyword(s):  
Optical Absorption ◽  
Absorption Maximum ◽  
Pulse Radiolysis ◽  
Electron Pulse ◽  
Density Range ◽  
Supercritical State ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Absorption Energy ◽  
Increasing Temperature

The optical absorption spectra of the solvated electron ([Formula: see text]) in sub- and super-critical methanol are measured by both electron pulse radiolysis and laser photolysis techniques, at temperatures in the range 220–270 °C. Over the density range studied (~0.45–0.59 g/cm3), the position of the absorption maximum ([Formula: see text]) of [Formula: see text] is found to shift only slightly to the red with decreasing density. In agreement with our previous work in water, at a fixed pressure, [Formula: see text] decreases monotonically with increasing temperature in passing through the phase transition at Tc (239.5 °C). By contrast, at a fixed density, [Formula: see text] exhibits a minimum as the solvent passes above the critical point into the supercritical state. These behaviors are discussed in terms of microscopic arguments based on the changes that occur in the methanol properties and methanol structure in the sub- and super-critical regimes. The effect of the addition of a small amount of water to the alcohol on the optical absorption energy of [Formula: see text] is also investigated.

scholarly journals On the Primary Water Radicals’ Production in the Presence of Gold Nanoparticles: Electron Pulse Radiolysis Study

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2478
Author(s):  
Viacheslav Shcherbakov ◽  
Sergey A. Denisov ◽  
Mehran Mostafavi
Keyword(s):  
Gold Nanoparticles ◽  
Free Radical ◽  
Ionizing Radiation ◽  
Pulse Radiolysis ◽  
Biological Processes ◽  
Solvated Electrons ◽  
Direct Measurements ◽  
Primary Water ◽  
Free Radical Formation ◽  
Shed Light

Gold nanoparticles are known to cause a radiosensitizing effect, which is a promising way to improve radiation therapy. However, the radiosensitization mechanism is not yet fully understood. It is currently assumed that gold nanoparticles can influence various physical, chemical, and biological processes. Pulse radiolysis is a powerful tool that can examine one of the proposed effects of gold nanoparticles, such as increased free radical production. In this work, we shed light on the consequence of ionizing radiation interaction with gold nanoparticles by direct measurements of solvated electrons using the pulse radiolysis technique. We found that at a therapeutically relevant gold concentration (<3 mM atomic gold, <600 μg × cm−3), the presence of gold nanoparticles in solution does not induce higher primary radicals’ formation. This result contradicts some hypotheses about free radical formation in the presence of gold nanoparticles under ionizing radiation previously reported in the literature.

scholarly journals β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 5. Adsorption Isotherm and Equation of State Revisited, Impact of pH

2021 ◽  
Vol 5 (1) ◽  
pp. 14
Author(s):  
Georgi G. Gochev ◽  
Volodymyr I. Kovalchuk ◽  
Eugene V. Aksenenko ◽  
Valentin B. Fainerman ◽  
Reinhard Miller
Keyword(s):  
Theoretical Description ◽  
Fluid Interfaces ◽  
Interfacial Behavior ◽  
Current State ◽  
Air Interface ◽  
Direct Measurements ◽  
Wide Range ◽  
Dilational Viscoelasticity ◽  
Parameter Values ◽  
Β Lactoglobulin

The theoretical description of the adsorption of proteins at liquid/fluid interfaces suffers from the inapplicability of classical formalisms, which soundly calls for the development of more complicated adsorption models. A Frumkin-type thermodynamic 2-d solution model that accounts for nonidealities of interface enthalpy and entropy was proposed about two decades ago and has been continuously developed in the course of comparisons with experimental data. In a previous paper we investigated the adsorption of the globular protein β-lactoglobulin at the water/air interface and used such a model to analyze the experimental isotherms of the surface pressure, Π(c), and the frequency-, f-, dependent surface dilational viscoelasticity modulus, E(c)f, in a wide range of protein concentrations, c, and at pH 7. However, the best fit between theory and experiment proposed in that paper appeared incompatible with new data on the surface excess, Γ, obtained from direct measurements with neutron reflectometry. Therefore, in this work, the same model is simultaneously applied to a larger set of experimental dependences, e.g., Π(c), Γ(c), E(Π)f, etc., with E-values measured strictly in the linear viscoelasticity regime. Despite this ambitious complication, a best global fit was elaborated using a single set of parameter values, which well describes all experimental dependencies, thus corroborating the validity of the chosen thermodynamic model. Furthermore, we applied the model in the same manner to experimental results obtained at pH 3 and pH 5 in order to explain the well-pronounced effect of pH on the interfacial behavior of β-lactoglobulin. The results revealed that the propensity of β-lactoglobulin globules to unfold upon adsorption and stretch at the interface decreases in the order pH 3 > pH 7 > pH 5, i.e., with decreasing protein net charge. Finally, we discuss advantages and limitations in the current state of the model.

Article

1998 ◽  
Vol 76 (4) ◽  
pp. 411-413
Author(s):  
Yixing Zhao ◽  
Gordon R Freeman
Keyword(s):  
Absorption Spectrum ◽  
Optical Absorption ◽  
Temperature Dependence ◽  
Optical Absorption Spectrum ◽  
Infrared Light ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Tert Butanol ◽  
Solvent Dependence ◽  
Increasing Temperature

The energy and asymmetry of the optical absorption spectrum of solvated electrons, es- , change in a nonlinear fashion on changing the solvent through the series HOH, CH3OH, CH3CH3OH, (CH3)2CHOH, (CH3)3COH. The ultimate, quantum-statistical mechanical, interpretation of solvated electron spectra is needed to describe the solvent dependence. The previously reported optical spectrum of es- in tert-butanol was somewhat inaccurate, due to a small amount of water in the alcohol and to limitations of the infrared light detector. The present note records the remeasured spectrum and its temperature dependence. The value of the energy at the absorption maximum (EAmax) is 155 zJ (0.97 eV) at 299 K and 112 zJ (0.70 eV) at 338 K; the corresponding values of G epsilon max (10-22 m2 aJ-1) are 1.06 and 0.74. These unusually large changes are attributed to the abnormally rapid decrease of dielectric permittivity of tert-butanol with increasing temperature. The band asymmetry at 299 K is Wb/Wr = 1.8.Key words: optical absorption spectrum, solvated electron, solvent effects, tert-butanol, temperature dependence.

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