Oxygen electron attachment

Chromium(VI) oxide, C1O3, is the anhydride of chromic acid, H2Cr04, the parent acid of the chromates. In this highly oxidized state, chromium is electron poor and the oxygen atoms attached to it are less likely to share electrons with a proton. 

Here symbols in parentheses represent unshared electrons attached to C and O, respectively, and those in braces represent shared electrons. An excited carbon atom 6S lies about 1.6 v. e. above the normal state, but can still form only a double bond with oxygen, so that the resultant molecule should be excited. We write... 

Because oxygen is probably the most extensively studied molecule in both experimental and theoretical investigations of low-energy electron attachment, the experimental results and detailed discussion are presented in this paper particularly for O2. The only accepted mechanism has been the overall two-step three-body mechanism, which was originally suggested by Bloch and Bradbury [79] (referred to below as BB ) and was later modified by Herzenberg [80] to make it consistent with modern experimental data. The BB mechanism for O2-M mixture, where M is a molecule other than O2, is expressed as follows ... 

The crystal of CaO assumes the NaCl structure, the closest approach between positive and negative ions being 239 pm. The enthalpy of atomization of calcium metal is 193 kJ mol that of dioxygen is 248 kJ moT1 (of oxygen atoms). The two electron attachment enthalpies of oxygen are -148 and +838 kJ mol respectively. The first and second successive ionization enthalpies of calcium are 596 and 1156 kJ mol respectively. Use the data to calculate a value for the standard enthalpy of formation of calcium oxide and compare the result with the experimental value of -635 kJ mol... 

A water molecule contains two hydrogen atoms and one oxygen atom. Hydrogen and hydroxyl radicals can be produced from the dissociation [93] or dissociative electron attachment of water [94] ... 

A comparison of the nature of the DNA-radicals produced with y-radiation relative to those produced by ion-beams shows that some radical species which are found in low amounts using /-radiation (low LET) increase by an order of magnitude in absolute yield with ion-beam (high LET) irradiation. For example, work using oxygen ion-beams found evidence for a phosphoryl radical (R0P02 , Scheme 1) in DNA. This radical, formed by dissociative electron attachment (Sec. 3), is clear evidence for a prompt strand break.In addition, formation of sugar radicals via exited states was proposed (Sec. 2.7). 

The formation of Q might then proceed as follows. A low energy electron attaches to the P ground state of the oxygen atom to form 0 (2p P ). 

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