Recoil Tritium Reactions: Pressure-dependent Reactions with Cyclobutane

The hot atom chemistry of muonium in alkane vapors

“…studies in (light) hot atom chemistry (3)(4)(5)(6), in which the incident triton is produced with kinetic energies -100 keV, orders of magnitude larger than those of chemical interest. This is also the situation in Mu formation and hence the hot Mu (Mu*) chemistry in alkane vapors discussed here should be directly comparable with similar studies of T* reactivity (21)(22)(23)(24)(25)(26)(27).…”

“…As a consequence, it is difficult to compare results from different laboratories and, in some cases, even to extract total yields from a given publication. Nevertheless, by examining a number of representative reports of both absolute yields and HT/RT ratios (21)(22)(23)(24)(25)(26)(27) one can hope to arrive at a reasonably reliable set of absolute T* yields with which the fD values found in Mu* chemistry ( For personal use only.…”

“…In analogy with hot tritium studies (7)(8)(9)(21)(22)(23)(24)(25)(26)(27) where the * indicates the possibility of forming translationally or rovibrationally excited product molecules, for which thirdbody collisions may be required to form a stable product. In hot tritium studies, the ratio of HT/RT yields exhibits a rather marked sensitivity to incident energy, pressure, moderator type, and to the nature of the hydrocarbon being attacked.…”

“…In the case of translational excitation, light moderators (He) are very efficient at cooling, and hence result in a relative increase in HT yield, whereas heavy moderators (Xe) have the opposite effect, promoting dissociation of HT* and hence a reduction in yield (26,35,43). On the other hand, in those same studies it has been shown that for a range of moderators of mass comparable to that of the CH3 group, such as Ne, there is little change in the HT/RT ratio; in addition, these ratios and the total yields are found to be essentially pressure independent for the alkanes up to n = 4 (21)(22)(23)(24)(25)(26)35). This is important for the present comparison of Mu* and T* reactivity in pure alkanes, since differences in measured yields can be construed as largely reflecting differences in hot atom reactivity rather than in moderation.…”

“…Although there is ample evidence that neither Mu* (Table 1 nd refs. 28-30) nor T* (21)(22)(23)(24)(25)(26)44) yields are dramatically ependent on total pressure, in general some pressure depenence is expected, particularly for substitution reactions (eq. I), depending on the level of residual excitation in the RT* u*) product formed.…”