Observation of the isotope effect in sub-kelvin reactions.

摘要: Quantum phenomena in the translational motion of reactants, which are usually negligible at room temperature, can dominate reaction dynamics low temperatures. In such cold conditions, even weak centrifugal force is enough to create a potential barrier that keeps reactants separated. However, reactions may still proceed through tunnelling because, temperatures, wave-like properties become important. At certain de Broglie wavelengths, colliding particles trapped long-lived metastable scattering states, leading sharp increases total rate. Here, we show these states responsible for dramatic, order-of-magnitude-strong, quantum kinetic isotope effect by measuring absolute Penning ionization rates between hydrogen isotopologues and helium down 0.01 K. We demonstrate measurements single insufficient constrain ab initio calculations, making regime necessary remove ambiguity among possible energy surfaces.