Pulsed electron spin resonance—Applications to photoionization processes

Abstract

Several new aspects of pulsed electron spin resonance methods are described with emphasis on detection of weak hyperfine interactions of a paramagnetic species to give environmental information that is not normally possible with continuous wave methods. The electron spin echo modulation technique is used primarily to measure such weak hyperfine interactions. It is shown that variable pulse sequence repetition rates can be used to separate echo responses from overlapping radicals with different relaxation times in frozen vesicle systems in which photoionization has occured. Pulsed light excitation with electron spin resonance detection has been used to study transient triplet states in frozen vesicles. The external heavy atom affect induced by adding sodium iodide has been shown to be a control method to affect the net photoionization efficiency in frozen vesicle systems. Electron spin echo modulation is also used to monitor location control of an electron donor or acceptor at an interface by added alkyl chains.