Tritium scattered

It should be noted that in enols of (3-diketones (acetyl- and benzoylacetone, dibenzoylmethane) the largest primary negative isotope effect is observed, for deuterium between 0.6 and 0.7 ppm and for tritium between —0.8 and —1.0 ppm [70, 71]. It corroborates the double-well character of proton potential in compounds of this group. Even in the shortest intramolecular OHO bridge in 4-cyano-2,2,6, 6-tetramethyl-3,5-heptanedione [55], of 2.393 A length (see Sect. 10) it was evidenced, based on neutron diffraction and inelastic scattering, a double minimum potential with very low barrier. The authors of the cited paper believe the existence of single minimum potential to be unlikely in compounds of this type. 

Surface ionization studies of Reaction 1 necessarily involved the detection of the much heavier product, KBr, which was constrained by the conservation of momentum to scatter close to the center of mass (c.m.). In this case, the small recoil velocity of the product KBr from the c.m. is masked by the spread of the c.m. velocity vectors arising from the distribution of parent beam velocities. Thus, it becomes diflBcult to extract any information about the motion of the KBr relative to the c.m., which would provide the desired description of the mechanism and energetics of the reaction (9). High velocity resolution experiments have since been done by Bernstein and coworkers (10,11), but the studies of Reactions 2 and 3 by Martin and Kinsey (8) were the first to provide some information on the dynamics of these reactions from a measurement of product distributions. In these experiments tritium labeling allowed radioisotope... 

Estimation of the average molecular weights for [PcMO] (M=Si, Ge, Sn) by IR end-group analysis, tritium labeling and laser light scattering experiments... 

---