Prior distributions Information-theoretic analysis

Nowadays, phase-space theory is mainly used to generate least-biased state distributions in an information-theoretic analysis of experimental data/ ° This approach was first formulated by Bernstein and Levine and has been extended and widely applied over the past few years. A central feature of the method is its proposal of a quantitative measure of the surprisal of a particular outcome, for example, the observation that in the reaction H + CI2 -> HCl -I- Cl, 42% of the HCl molecules are formed in i = 3. To do this, it is necessary to define one s prior expectation. If the observed result coincides with this, it causes no surprise. The prior is usually provided by the least biased choice obtained via phase-space theory. ... 

Figure 1.1. Information-theoretic analysis of detailed rate constants for the reaction O + CS CO(i ) + S. Panel (a) compares P(/v), the observed distribution over v from the exothermic reaction, to the distribution expected on prior grounds. Panel (b) shows the surprisal associated with this distribution. In panel (c), the values of ki v r), calculated from detailed balancing, are plotted against e lksT for T = 300 K. [Reproduced, with permission, from I. W. M. Smith, Specialist Periodical Reports Gas Kinetics and Energy Transfer Vol. 2 (P. G. Ashmore and R. J. Donovan eds.). Chemical Society, London (1977).]...

The analysis of the data of PS I gave quite accurate information on the distance of the spin centres (25.4 0.3 A)301 that compared well with the crystal structure data.68 A problem is the extended it-spin density distribution in the donor and acceptor. For a solid comparison a centre of gravity for the spin must be calculated from experimental or theoretical spin density distributions of the two radicals. Similar data with almost unaltered distances were obtained for PS I with other quinones substituted into the Ai site.147-302This work has been extended to other electron acceptors,303 which show a larger heterogeneity in distances. It has been shown that the lifetime of the RP can also be measured and can even be controlled in the experiments by an additional mw pulse prior to the 2-pulse echo sequence.302 This pulse transfers population to triplet levels which cannot directly recombine to the singlet ground state. This has earlier been shown for the bRC.304,305 The OOP-ESEEM technique has also been applied to various mutants of PS I to characterize them by the measured distances between fixed donor and variable acceptors.254 256-263-264... 

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