A theoretical study of electron spin resonance spectra of nitroxide free radicals

• Main Author: Itzkowitz, Martin Stanley
• Format: Others
• Published: 1967
• Online Access: https://thesis.library.caltech.edu/3510/1/Itzkowitz_ms_1967.pdf; Itzkowitz, Martin Stanley (1967) A theoretical study of electron spin resonance spectra of nitroxide free radicals. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/EA9P-5Z37. https://resolver.caltech.edu/CaltechETD:etd-09132002-115317 <https://resolver.caltech.edu/CaltechETD:etd-09132002-115317>

We are concerned with the electron spin resonance spectra of nitroxide free radicals in various molecular environments. These radicals may be described as a single electron interacting anisotropically with an external field and a nitrogen nucleus of spin one. We use both exact and approximate solutions to the hamiltonian to simulate spectra from oriented samples. We then perform the orientation averages to obtain theoretical spectra from polycrystalline samples. We consider the effects of molecular motion on the system, and develop a Monte Carlo scheme to evaluate the spectrum for a variety of molecular tumbling rates. The theoretical spectra so computed are compared with experimental spectra taken in solutions of varying rotational correlation time; excellent agreement is obtained. We use the Monte Carlo calculation to estimate the rotational correlation time for the molecule in solution.