26
|
Kumar A, Walker JA, Bartels DM, Sevilla MD. A Simple ab Initio Model for the Hydrated Electron That Matches Experiment. J Phys Chem A 2016; 119:9148-59. [PMID: 26275103 DOI: 10.1021/acs.jpca.5b04721] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Since its discovery over 50 years ago, the "structure" and properties of the hydrated electron have been a subject for wonderment and also fierce debate. In the present work we seriously explore a minimal model for the aqueous electron, consisting of a small water anion cluster embedded in a polarized continuum, using several levels of ab initio calculation and basis set. The minimum energy "zero Kelvin" structure found for any 4-water (or larger) anion cluster, at any post-Hartree–Fock theory level, is very similar to a recently reported embedded-DFT-in-classical-water-MD simulation (Uhlig, Marsalek, and Jungwirth, J. Phys. Chem. Lett. 2012, 3, 3071−3075), with four OH bonds oriented toward the maximum charge density in a small central "void". The minimum calculation with just four water molecules does a remarkably good job of reproducing the resonance Raman properties, the radius of gyration derived from the optical spectrum, the vertical detachment energy, and the hydration free energy. For the first time we also successfully calculate the EPR g-factor and (low temperature ice) hyperfine couplings. The simple tetrahedral anion cluster model conforms very well to experiment, suggesting it does in fact represent the dominant structural motif of the hydrated electron.
Collapse
|
27
|
Sterniczuk M, Yakabuskie PA, Wren JC, Jacob JA, Bartels DM. Low LET radiolysis escape yields for reducing radicals and H2 in pressurized high temperature water. Radiat Phys Chem Oxf Engl 1993 2016. [DOI: 10.1016/j.radphyschem.2015.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
28
|
Walker JA, Mezyk SP, Roduner E, Bartels DM. Isotope Dependence and Quantum Effects on Atomic Hydrogen Diffusion in Liquid Water. J Phys Chem B 2016; 120:1771-9. [PMID: 26623663 DOI: 10.1021/acs.jpcb.5b09375] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Relative diffusion coefficients were determined in water for the D, H, and Mu isotopes of atomic hydrogen by measuring their diffusion-limited spin-exchange rate constants with Ni(2+) as a function of temperature. H and D atoms were generated by pulse radiolysis of water and measured by time-resolved pulsed EPR. Mu atoms are detected by muonium spin resonance. To isolate the atomic mass effect from solvent isotope effect, we measured all three spin-exchange rates in 90% D2O. The diffusion depends on the atomic mass, demonstrating breakdown of Stokes-Einstein behavior. The diffusion can be understood using a combination of water "cavity diffusion" and "hopping" mechanisms, as has been proposed in the literature. The H/D isotope effect agrees with previous modeling using ring polymer molecular dynamics. The "quantum swelling" effect on muonium due to its larger de Broglie wavelength does not seem to slow its "hopping" diffusion as much as predicted in previous work. Quantum effects of both the atom mass and the water librations have been modeled using RPMD and a qTIP4P/f quantized flexible water model. These results suggest that the muonium diffusion is very sensitive to the Mu versus water potential used.
Collapse
|
29
|
Sterniczuk M, Bartels DM. Source of Molecular Hydrogen in High-Temperature Water Radiolysis. J Phys Chem A 2016; 120:200-9. [DOI: 10.1021/acs.jpca.5b12281] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
30
|
Kanjana K, Courtin B, MacConnell A, Bartels DM. Reactions of Hexa-aquo Transition Metal Ions with the Hydrated Electron up to 300 °C. J Phys Chem A 2015; 119:11094-104. [DOI: 10.1021/acs.jpca.5b08812] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
31
|
Kanjana K, Walker JA, Bartels DM. Hydroxymethyl radical self-recombination in high-temperature water. J Phys Chem A 2015; 119:1830-7. [PMID: 25686211 DOI: 10.1021/jp510029p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The self-recombination reaction of (•)CH2OH radicals in neutral aqueous solution has been studied at temperatures up to 300 °C at a pressure of 220 bar using pulse radiolysis and transient absorption. (•)CH2OH species decay by second-order kinetics independent of the applied dose, with a rate constant at 22 °C of 2k = 1.4 ± 0.1 × 10(9) M(-1) s(-1). The recombination follows Arrhenius behavior with the activation energy (E(a)) 12.7 ± 0.9 kJ/mol and pre-exponential factor of 1.9 ± 0.4 × 10(11) M(-1) s(-1). The overall recombination is significantly slower than the diffusion limit at elevated temperature, meaning that both disproportionation and dimerization channels have significant activation barriers. Ab initio calculations support the inference that the dimerization channel has no energy barrier, but has a large negative activation entropy barrier. The disproportionation channel (giving aqueous formaldehyde) almost certainly involves one or more specific water molecules to lower its activation energy relative to the gas phase.
Collapse
|
32
|
Nuzhdin K, Bartels DM. Hyperfine coupling of the hydrogen atom in high temperature water. J Chem Phys 2013; 138:124503. [PMID: 23556732 DOI: 10.1063/1.4795005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The hyperfine coupling constant of the hydrogen atom has been measured in pressurized liquid water up to 300 °C. The reduced constant A(water)∕A(vacuum) is 0.9939 at room temperature, and decreases to a minimum of 0.9918 at 240 °C. The reduced constant then increases at higher temperature. The g-factor is 2.002244(10) at room temperature and decreases to 2.00221(1) at 240 °C. The change in g-factor is proportional to the change in hyperfine coupling. The behavior below 110 °C is in excellent agreement with a previously proposed model in which the H atom is confined to a harmonic solvent cage, and vibrations within the cage mix "p-type" character into the wavefunction, resulting inA(water)∕A(vacuum) < 1. The harmonic model breaks down above 130 °C. We demonstrate that a classical binary collision model using approximate partial molar volume information can recover the observed minima near 240 °C.
Collapse
|
33
|
Kanjana K, Haygarth KS, Wu W, Bartels DM. Laboratory studies in search of the critical hydrogen concentration. Radiat Phys Chem Oxf Engl 1993 2013. [DOI: 10.1016/j.radphyschem.2012.09.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
34
|
Patterson LK, Mazière JC, Bartels DM, Hug GL, Santus R, Morlière P. Evidence for a slow and oxygen-insensitive intra-molecular long range electron transfer from tyrosine residues to the semi-oxidized tryptophan 214 in human serum albumin: its inhibition by bound copper (II). Amino Acids 2010; 42:1269-75. [DOI: 10.1007/s00726-010-0819-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 11/22/2010] [Indexed: 11/29/2022]
|
35
|
Song J, Ratner ER, Wall MM, Bartels DM, Ulvestad N, Petroskas D, West M, Weber-Main AM, Grengs L, Gelberg L. Summaries for patients. End-of-Life Planning intervention and the Completion of Advance Directives in homeless persons. Ann Intern Med 2010; 153:I-38. [PMID: 20643975 DOI: 10.7326/0003-4819-153-2-201007200-00001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|
36
|
Haygarth K, Bartels DM. Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 2. SF6 as a Scavenger for Hydrated Electron. J Phys Chem A 2010; 114:7479-84. [DOI: 10.1021/jp1025366] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
37
|
Haygarth KS, Marin TW, Janik I, Kanjana K, Stanisky CM, Bartels DM. Carbonate radical formation in radiolysis of sodium carbonate and bicarbonate solutions up to 250 degrees C and the mechanism of its second order decay. J Phys Chem A 2010; 114:2142-50. [PMID: 20078055 DOI: 10.1021/jp9105162] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Pulse radiolysis experiments published several years ago (J. Phys. Chem. A, 2002, 106, 2430) raised the possibility that the carbonate radical formed from reaction of *OH radicals with either HCO(3)(-) or CO(3)(2-) might actually exist predominantly as a dimer form, for example, *(CO(3))(2)(3-). In this work we re-examine the data upon which this suggestion was based and find that the original data analysis is flawed. A major omission of the original analysis is the recombination reaction *OH + *CO(3)(-) --> HOOCO(2)(-). Upon reanalysis of the published data for sodium bicarbonate solutions and analysis of new transient absorption data we are able to establish the rate constant for this reaction up to 250 degrees C. The mechanism for the second-order self-recombination of the carbonate radical has never been convincingly demonstrated. From a combination of literature data and new transient absorption experiments in the 1-400 ms regime, we are able to show that the mechanism involves pre-equilibrium formation of a C(2)O(6)(2-) dimer, which dissociates to CO(2) and peroxymonocarbonate anion: *CO3(-)+*CO3(-)<-->C2O6(2-)-->CO2+O2COO(2-) *CO3(-) reacts with the product peroxymonocarbonate anion, producing a peroxymonocarbonate radical *O2COO(-), which can also recombine with the carbonate radical: *CO3(-)+CO4(2-)-->*CO4(-)+CO3(2-) *CO3(-)+CO4(-)-->C2O7(2-).
Collapse
|
38
|
Haygarth K, Janik D, Janik I, Bartels DM. Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H2, H· Atom, and Hydrated Electron. J Phys Chem A 2010. [DOI: 10.1021/jp101790p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
39
|
Hare PM, Price EA, Stanisky CM, Janik I, Bartels DM. Solvated Electron Extinction Coefficient and Oscillator Strength in High Temperature Water. J Phys Chem A 2010; 114:1766-75. [DOI: 10.1021/jp909789b] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
40
|
Stanisky CM, Bartels DM, Takahashi K. Rate constants for the reaction of hydronium ions with hydrated electrons up to 350°C. Radiat Phys Chem Oxf Engl 1993 2010. [DOI: 10.1016/j.radphyschem.2009.08.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
41
|
Mezyk SP, Hardison DR, Song W, O'Shea KE, Bartels DM, Cooper WJ. Advanced oxidation and reduction process chemistry of methyl tert-butyl ether (MTBE) reaction intermediates in aqueous solution: 2-methoxy-2-methyl-propanal, 2-methoxy-2-methyl-propanol, and 2-methoxy-2-methyl-propanoic acid. CHEMOSPHERE 2009; 77:1352-1357. [PMID: 19853274 DOI: 10.1016/j.chemosphere.2009.09.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2009] [Revised: 09/15/2009] [Accepted: 09/16/2009] [Indexed: 05/28/2023]
Abstract
Absolute rate constants for the reaction of three important degradation products of methyl-tert-butyl ether (MTBE) with the hydroxyl radical, hydrated electron and hydrogen atom were determined in aqueous solution at room temperature. These three intermediate species; 2-methoxy-2-methyl propanal (MMP), 2-methoxy-2-methyl-propanol (MMP-OH) and 2-methoxy-2-methyl-propionic acid (MMP-acid), are formed in the degradation of MTBE under advanced oxidation and reduction process conditions. The rate constants for their hydroxyl radical oxidation of (3.99+/-0.29)x10(9), (8.02+/-0.53)x10(8), and (7.73+/-0.48)x10(8)M(-1)s(-1), respectively, show that this reaction would be the overall dominant degradation pathway for these three compounds, relative to their corresponding hydrated electron reduction values of (3.11+/-0.32)x10(7), (7.8+/-1.8)x10(6) and (1.40+/-0.10)x10(9)M(-1)s(-1), and hydrogen atom rate constants of (1.65+/-0.14)x10(7), (1.30+/-0.13) x10(8) and <1.2 x 10(6)M(-1)s(-1).
Collapse
|
42
|
Tarábek P, Liu S, Haygarth K, Bartels DM. Hydrogen gas yields in irradiated room-temperature ionic liquids. Radiat Phys Chem Oxf Engl 1993 2009. [DOI: 10.1016/j.radphyschem.2008.11.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
43
|
Hare PM, Price EA, Bartels DM. Hydrated Electron Extinction Coefficient Revisited. J Phys Chem A 2008; 112:6800-2. [DOI: 10.1021/jp804684w] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
44
|
Edwards EJ, Wilson PPH, Anderson MH, Mezyk SP, Pimblott SM, Bartels DM. An apparatus for the study of high temperature water radiolysis in a nuclear reactor: calibration of dose in a mixed neutron/gamma radiation field. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:124101. [PMID: 18163737 DOI: 10.1063/1.2814167] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The cooling water of nuclear reactors undergoes radiolytic decomposition induced by gamma, fast electron, and neutron radiation in the core. To model the process, recombination reaction rates and radiolytic yields for the water radical fragments need to be measured at high temperature and pressure. Yields for the action of neutron radiation are particularly hard to determine independently because of the beta/gamma field also present in any reactor. In this paper we report the design of an apparatus intended to measure neutron radiolysis yields as a function of temperature and pressure. A new methodology for separation of neutron and beta/gamma radiolysis yields in a mixed radiation field is proposed and demonstrated.
Collapse
|
45
|
Filipe P, Patterson LK, Bartels DM, Hug GL, Freitas JP, Mazière JC, Santus R, Morlière P. Albumin-Bound Quercetin Repairs Vitamin E Oxidized by Apolipoprotein Radicals in Native HDL3 and LDL. Biochemistry 2007; 46:14305-15. [DOI: 10.1021/bi701419d] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
46
|
Marin TW, Takahashi K, Jonah CD, Chemerisov SD, Bartels DM. Recombination of the Hydrated Electron at High Temperature and Pressure in Hydrogenated Alkaline Water. J Phys Chem A 2007; 111:11540-51. [DOI: 10.1021/jp074581r] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
47
|
Marin TW, Takahashi K, Bartels DM. Temperature and density dependence of the light and heavy water ultraviolet absorption edge. J Chem Phys 2007; 125:104314. [PMID: 16999533 DOI: 10.1063/1.2338521] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Characteristics of the ultraviolet absorption band edge of high-pressure light and heavy water are reported over the temperature range of 25-400 degrees C, extending into the supercritical regime. A gradual redshift in the absorption band edge of approximately 0.6 eV is observed with increasing temperature. This shift cannot be explained by vibrational hot band growth or changes in the degree of Rayleigh scattering with increasing temperature, and is ascribed to a shift of the electronic transition energy. The density dependence for the absorption edge in 400 degrees C supercritical water was also examined, and showed a surprising approximately 0.1 eV blueshift over a factor of 3.5 decrease in density. This shift may be due to a narrowing of the absorption spectrum with decreasing density. It is proposed that the previously reported "red tail" of the water absorption extending into the near ultraviolet and visible could be attributed to preresonant Rayleigh scattering, and that the true onset of liquid water absorption is approximately 5.8 eV at 25 degrees C.
Collapse
|
48
|
Janik D, Janik I, Bartels DM. Neutron and β/γ Radiolysis of Water up to Supercritical Conditions. 1. β/γ Yields for H2, H• Atom, and Hydrated Electron. J Phys Chem A 2007; 111:7777-86. [PMID: 17645317 DOI: 10.1021/jp071751r] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Yields for H2, H(.) atom, and hydrated electron production in beta/gamma radiolysis of water have been measured from room temperature up to 400 degrees C on a 250 bar isobar, and also as a function of pressure (density) at 380 and 400 degrees C. Radiolysis was carried out using a beam of 2-3 MeV electrons from a van de Graaff accelerator, and detection was by mass spectrometer analysis of gases sparged from the irradiated water. N2O was used as a specific scavenger for hydrated electrons giving N2 as product. Ethanol-d(6) was used to scavenge H(.) atoms, giving HD as a stable product. It is found that the hydrated electron yield decreases and the H(.) atom yield increases dramatically at lower densities in supercritical water, and the overall escape yield increases. The yield of molecular H2 increases with temperature and does not tend toward zero at low density, indicating that it is formed promptly rather than in spur recombination. A minimum in both the radical and H2 yields is observed around 0.4 kg/dm(3) density in supercritical water.
Collapse
|
49
|
Boullier A, Mazière JC, Filipe P, Patterson LK, Bartels DM, Hug GL, Freitas JP, Santus R, Morlière P. Interplay of oxygen, vitamin E, and carotenoids in radical reactions following oxidation of Trp and Tyr residues in native HDL3 apolipoproteins. Comparison with LDL. A time-resolved spectroscopic analysis. Biochemistry 2007; 46:5226-37. [PMID: 17411073 DOI: 10.1021/bi602530g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It has been recently shown that the inhibition of apolipoprotein A-I (apoAI) reverse cholesterol transport activity during oxidation of HDL by myeloperoxidase may involve myeloperoxidase electron transfer pathways other than those leading to tyrosine chlorination. To better understand how such mechanisms might be initiated, the role of semioxidized Tyr and Trp residues in loss of apoAI and apolipoprotein A-II (apoAII) integrity has been assessed using selective Trp and Tyr one-electron oxidation by *Br2(-) radical-anions in HDL3 as well as in unbound apoAI and apoAII. Behavior of these radicals in apolipoprotein B of LDL has also been assessed. Formation of semioxidized Tyr in HDL3 is followed by partial repair during several milliseconds via reaction with endogenous alpha-tocopherol to form the alpha-tocopheroxyl radical. Subsequently, 2% of alpha-tocopheroxyl radical is repaired by HDL3 carotenoids. With LDL, a faster repair of semioxidized Tyr by alpha-tocopherol is observed, but carotenoid repair of alpha-tocopheroxyl radical is not. Only a small fraction of HDL3 particles contains alpha-tocopherol and carotenoids, which explains limited repair of semioxidized Tyr by alpha-tocopherol. All LDL particles normally contain multiple alpha-tocopherol and carotenoid molecules, and the lack of repair of alpha-tocopheroxyl radical by carotenoids probably results from hindered mobility of carotenoids in the lipid core. Western blots of gamma-irradiated HDL3 comparable to those reported for apoAI myeloperoxidase oxidation show that the incomplete repair of semioxidized Tyr and Trp induces apoAI and apoAII permanent damage including formation of a heterodimer of one apoAI with a monomeric apoAII at about 36 kDa.
Collapse
|
50
|
|