[Kuwait_chemist]

Hello guys
i was wondering if any one can brief me on ESR?
what does it mean? and why is it used? what kind of characrization is it used for?

[pheonix6]

ESR (electron spin resonance) is also known as electron paramagnetic resonance (EPR) spectroscopy.  It is a technique which can be applied; at least in principle to all systems where unpaired electron spins are present.  for example it allows the determination of structural properties on a molecular scale; the selective characterisation of redox-active centres in proteins; the study of the kinetics of chemical reactions.
For details it would be best to check either phys chem textbooks eg. Atkins or prehaps see if there is a book in the oxford chemistry primers series which covers the topic in greater depth.