Relative relaxation-efficiency between

From these studies of sugars and related molecules, it is possible to derive empirical rules whereby Ri(ns) values can be used as the basis for configurational assignments. These rules are illustrated graphically in Fig. 5, where the relative relaxation-efficiency between two protons is plotted as a function of the interproton distance. 

Fig. 5.—Plot of the Relative Relaxation Efficiency between Two Protons versus the Inverse Sixth Power of Their Internuclear Separation. (Derived from measurements of Dreiding stereomodels reproduced, with permission, from Ref. 43.)...

Low temperature experiments have shown the formation of hypso intermediates from several species [99,103,105-107]. The study of early photoconversion processes in squid [108], which also involved the evaluation of the relative quantum yields among the four pigments (squid rhodopsin, squid batho-, hypso- and isorhodopsin) showed that hypsorhodopsin is a common intermediate of rhodopsin and isorhodopsin there is no direct conversion between rhodopsin and isorhodopsin bathorhodopsin is not converted directly to hypsorhodopsin and both rhodopsin and isorhodopsin convert more efficiently to bathorhodopsin than to hypsorhodopsin. While a temperature dependence of the relaxation processes from the excited state of rhodopsin, and an assumption that batho could be formed from one of the high vibrational levels of the ground state hypso have been invoked to explain these findings [108], the final clarification of this matter awaits results from subpicosecond laser photolysis experiments at liquid helium temperature. 

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