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Full-Text Articles in Physical Sciences and Mathematics
Concerted Ho2 Elimination From Alpha-Aminoalkylperoxyl Free Radicals: Experimental And Theoretical Evidence From The Gas-Phase Nh2 Chco2 - + O2 Reaction, Gabriel Da Silva, Benjamin Kirk, Celli Lloyd, Adam Trevitt, Stephen Blanksby
Concerted Ho2 Elimination From Alpha-Aminoalkylperoxyl Free Radicals: Experimental And Theoretical Evidence From The Gas-Phase Nh2 Chco2 - + O2 Reaction, Gabriel Da Silva, Benjamin Kirk, Celli Lloyd, Adam Trevitt, Stephen Blanksby
Adam Trevitt
We have investigated the gas-phase reaction of the α- aminoacetate (glycyl) radical anion (NH2 •CHCO2−) with O2 using ion trap mass spectrometry, quantum chemistry, and statistical reaction rate theory. This radical is found to undergo a remarkably rapid reaction with O2 to form the hydroperoxyl radical (HO2 •) and an even-electron imine (NHCHCO2−), with experiments and master equation simulations revealing that reaction proceeds at the ion−molecule collision rate. This reaction is facilitated by a low-energy concerted HO2 • elimination mechanism in the NH2CH(OO•)CO2− peroxyl radical. These findings can explain the widely observed free-radical-mediated oxidation of simple amino acids to amides …
Gas-Phase Reactions Of Aryl Radicals With 2-Butyne: An Experimental And Theoretical Investigation Employing The N-Methyl-Pyridinium-4-Yl Radical Cation, Adrian Lam, Cong Li, George Khairallah, Benjamin Kirk, Stephen Blanksby, Adam Trevitt, Uta Wille, Richard O'Hair, Gabriel Da Silva
Gas-Phase Reactions Of Aryl Radicals With 2-Butyne: An Experimental And Theoretical Investigation Employing The N-Methyl-Pyridinium-4-Yl Radical Cation, Adrian Lam, Cong Li, George Khairallah, Benjamin Kirk, Stephen Blanksby, Adam Trevitt, Uta Wille, Richard O'Hair, Gabriel Da Silva
Adam Trevitt
Aromatic radicals form in a variety of reacting gas-phase systems, where their molecular weight growth reactions with unsaturated hydrocarbons are of considerable importance. We have investigated the ion–molecule reaction of the aromatic distonic N-methyl-pyridinium-4-yl (NMP) radical cation with 2-butyne (CH3C≡CCH3) using ion trap mass spectrometry. Comparison is made to high-level ab initio energy surfaces for the reaction of NMP and for the neutral phenyl radical system. The NMP radical cation reacts rapidly with 2-butyne at ambient temperature, due to the apparent absence of any barrier. The activated vinyl radical adduct predominantly dissociates via loss of a H atom, with lesser …
Infrared Spectra Of Cl-_(C6h6)Mm=1, 2, Christopher Thompson, Berwyck Poad, Corinna Emmeluth, Evan Bieske
Infrared Spectra Of Cl-_(C6h6)Mm=1, 2, Christopher Thompson, Berwyck Poad, Corinna Emmeluth, Evan Bieske
Berwyck L. J. Poad
The Cl--(C6H6)Arn n = 0,1,2 and Cl--(C6H6)2 complexes are investigated using photodissociation infrared spectroscopy in the CH stretch region and through ab initio calculations at the MP2/aug-cc-pVDZ level. The results indicate that Cl--C6H6 possesses a planar structure in which the benzene molecule is attached to the Cl- anion by a double hydrogen bond. The calculations predict that Cl (C6H6)2 has a C2 symmetry structure in which the two face-to-face benzene molecules are attached to …
Single-Grain Osl Chronologies For Middle Palaeolithic Deposits At El Mnasra And El Harhoura 2, Morocco: Implications For Late Pleistocene Human-Environment Interactions Along The Atlantic Coast Of Northwest Africa, Zenobia Jacobs, Richard Roberts, Roland Nespoulet, M El Hajraoui, Andre Debenath
Single-Grain Osl Chronologies For Middle Palaeolithic Deposits At El Mnasra And El Harhoura 2, Morocco: Implications For Late Pleistocene Human-Environment Interactions Along The Atlantic Coast Of Northwest Africa, Zenobia Jacobs, Richard Roberts, Roland Nespoulet, M El Hajraoui, Andre Debenath
Richard G Roberts
Optically stimulated luminescence (OSL) measurements were made on individual, sand-sized grains of quartz from Middle Palaeolithic deposits at two cave sites (El Harhoura 2 and El Mnasra) on the Atlantic coast of Morocco. We were able to calculate OSL ages for 32 of the 33 samples collected from the Middle Palaeolithic deposits, including the earliest and latest Aterian levels at both sites. These ages reveal periods of occupation between about 110 and 95 ka (thousands of years ago), and at ~75 ka. A late Middle Palaeolithic occupation of El Harhoura 2 is also recorded at ~55 ka. Our single-grain OSL …