2011/01/27 by Donald G. Fleming, Donald J. Arseneau, Oleksandr Sukhorukov +6 · 4 citations
Engineering · Chemical Engineering · Pharmacology, Toxicology and Pharmaceutics · #Muon and positron interactions and applications #Ammonia Synthesis and Nitrogen Reduction #Chemical Reactions and Isotopes
paper · doi:10.1126/science.1199421
openalex publication_date 2011/01/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/23
The neutral muonic helium atom may be regarded as the heaviest isotope of the hydrogen atom, with a mass of ~4.1 atomic mass units ((4.1)H), because the negative muon almost perfectly screens one proton charge. We report the reaction rate of (4.1)H with (1)H(2) to produce (4.1)H(1)H + (1)H at 295 to 500 kelvin. The experimental rate constants are compared with the predictions of accurate quantum-mechanical dynamics calculations carried out on an accurate Born-Huang potential energy surface and with previously measured rate constants of (0.11)H (where (0.11)H is shorthand for muonium). Kinetic isotope effects can be compared for the unprecedentedly large mass ratio of 36. The agreement with accurate quantum dynamics is quantitative at 500 kelvin, and variational transition-state theory is used to interpret the extremely low (large inverse) kinetic isotope effects in the 10(-4) to 10(-2) range.