Reactions of atomic hydrogen in water : solvent and isotope effects.
It has been known for many years that hydrogen atoms can be easily created and studied in water using radiolytic techniques [1]. The use of CW EPR detection coupled with electron radiolysis proved extremely useful in estimating many reaction rates, and revealed the interesting phenomenon of chemically induced dynamic electron polarization (CIDEP) [2]. In recent years, we have made use of pulsed EPR detection to make precision reaction rate measurements which avoid the complications of CIDEP [3]. Activation energies and H/D isotope effects measured in these studies [4-14] will be described below. An interesting aspect of the hydrogen atom reactions is the effect of hydrophobic solvation. EPR evidence--an almost gas-phase hyperfine coupling and extremely narrow linewidth--is quite convincing to show that the H atom is just a minimally perturbed gas phase atom inside a small ''bubble''. In several systems we have found that the hydrophobic free energy of solvation dominates the solvent effect on reaction rates.
- Research Organization:
- Argonne National Lab., IL (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 11784
- Report Number(s):
- ANL/CHM/CP-98924; TRN: AH200118%%282
- Resource Relation:
- Conference: 218th American Chemical Society National Meeting, New Orleans, LA (US), 08/22/1999--08/26/1999; Other Information: PBD: 10 Jun 1999
- Country of Publication:
- United States
- Language:
- English
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