No abstract

No abstract

Thermal and UV degradation of four common space-grade polymer films have been studied in situ using electron spin resonance (ESR) spectroscopy. By recording subsequent spectra at a sufficient rate, the time dependence of the radical concentration could be followed, allowing more detailed study of the kinetics of the degradation process. The thermal degradation was found to consist of two main processes, one being a stabilization process and the other the actual degradation, whereas the UV experiments showed biexponential degradation kinetics. Additionally, to compare in situ and ex situ experiments, we monitored the stability of the generated radicals after the exposure. The radical concentration decreased only slightly when samples were stored in a vacuum, whereas storage in air led to a significant loss of radicals.

No abstract

The solvent dependence of the electronic coupling matrix element V within electron transfer theory has been investigated for the homogeneous electron self-exchange reaction of the 1 ,Cdiaminobenzene/l ,Cdiaminobenzene radical cation couple. Experimental results from both ESR line broadening effects and semi-empirical MO calculations within the framework of self-consistent reaction field theory show that V is solventindependent.