Electron spin resonance spectroscopy history

Progress in photochemistry could only be made following progress in spectroscopy and, in particular, the interpretation of spectra in at least semiquantitative terms, but history has shown that this was not enough. The arrival of new methods of analysis which permit determination of small amounts of products, the development of flash photolysis, nuclear magnetic resonance, and electron spin resonances which can yield valuable information about the natures of intermediate excited states, as well as of atoms and radicals, all have permitted the photochemist to approach the truly fundamental problem of photochemistry What is the detailed history of a molecule which absorbs radiation ... 

FIGURE 17.11 Prof. James F. Harrison of the Michigan State University Chemistry Department carried out early calculations on the excited states of molecules using accurate configuration interaction methods, particularly BH [27] under the direction of his advisor Prof Leland C. Allen at Princeton University. He was one of the first to use accurate computational methods to study the triplet methylene molecule CH2 which is very important in synthetic organic chemistry. In particular, his calculation of the electron spin resonance parameters of CH2 was a rare case of computational theory guiding experimental spectroscopy at a time in the history of quantum chemistry that estabhshed the credibility of such calculations. He is also a contributor to Chapters 16 and 17. 

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