Conrad A. Naleway

LET dependences of yields in the pulse radiolysis of aqueous systems with /sup 2/H/sup +/ and /sup 4/He/sup 2//sup +//sup 1/. [Aqueous KCNS solutions]

The variation of G((CNS)/sup -//sub 2/) with beam penetration depth, and hence with linear energy transfer (LET), is determined in aqueous KCNS solutions using 8-..mu..sec pulses of 20 MeV /sup 2/H/sup +/ and 40 HeV /sup 4/He/sup 2//sup +/. Because the OH radical is the only precursor of (CNS)/sup -//sub 2/, this system provides a measure of G(HO). The experimental results on (CNS)/sup -//sub 2/ are in agreement with theoretical results of a model previously used to describe experimental results on G(e/sup -//sub aq/) vs LET.

High-LET Pulse Radiolysis: 0?- and Oxygen Production in Tracks'

The production of

Theoretical analysis of the LET dependence of transient yields observed in pulse radiolysis with ion beams

{rm O}_{2}{}^{-}

Examination of charge alternation in CH4 and CH3F from ab initio LCAO SCF MO wavefunctions and their localized bond orbitals

in the radiolysis of water at pH 7 and 11 has been investigated using pulses of 20-MeV deuterons and 40-MeV alpha particles. The G-values of

Superexchange-pathway model for long-distance electronic couplings

{rm O}_{2}{}^{-}...

Theoretical Study of Long-Distance Electronic Coupling in H2C(CH2)n-2 CH2 Chains, n=3-16

A theoretical analysis of the LET dependence of transient yields 10/sup -5/ sec after energy deposition by /sup 2/H/sup +/ and /sup 4/He/sup 2 +/ is presented. The model used takes into account the separation of the track core and the delta-ray tracks. Diffusion-kinetics methods are used to calculate the time dependences of transient concentrations in the track core and in the delta-ray tracks. Since the model also specifies the relative energetic importances of the different energy-deposition modes, composite G values can be calculated for comparison with experiment, and the agreement is found to be satisfactory.

Superexchange Pathway Calculation of Electronic Coupling through Cyclohexane Spacers

The question of whether or not fluorine substitution produces charge alternation is examined for CH4 and CH3F. Two sets of ab initio LCAO SCF MO wavefunctions (one a 3 G STO based one, the other a double zeta based one) are analyzed via charge density, localized CH bond moment, and population analysis calculations. Although both sets of wavefunctions show a slightly more negative H region in CH3F relative to CH4, in qualitative agreement with earlier work by Pople et al., the differences are small, and their sources are not clear. For example, in the 3 G calculations the CH localized orbital is the essential source of the increased density in CH3F, while for the double zeta calculations the increased density is due to the tail of an F lone-pair orbital trans to the CH bond. Consideration of details of these studies as well as those from large STO based SCF MO wavefunctions by Arrighini et al., suggests that one will need very accurate wavefunctions to resolve the problem unambiguously.