QUANTUM TUNNELING OF D(H) ATOMS AND H-2(-) ANIONS IN SOLID HYDROGEN

This paper contains three results. First, the rate constants for the t unneling reaction HD + D --> H + D-2 in solid HD increase steeply with increasing temperature above 5 K, while they are almost independent o f temperature below 5 IC. A mechanism of a vacancy-assisted tunneling reaction is proposed to account for this temperature dependence. Secon d, a hydrogen atom and a hydrogen molecule form a van der Waals comple x in the Ar matrix at 20 K, where the tunneling reaction HD + D --> H + D-2 takes place in this complex. The analysis of well-resolved ESR s pectra of the complex determined the distance between a hydrogen atom and a hydrogen molecule as 2.3-2.5 Angstrom. Third the decay rate cons tants of H-2(-) anions in solid parahydrogen decrease with decreasing temperature below 6.6 K, attain the minimum value at 5 Ii; and then in crease with decreasing temperature in the range of 5 --> 2.7 K. The ab normal temperature dependence of the decay rate constants below 5 K is ascribed to a phonon-scattering process of quantum diffusion.