Purely Spatial Quantum Diffusion of H Atoms in Solid H_{2} at Temperatures below 1 K.

We report on a direct measurement of the quantum diffusion of H atoms in solid molecular hydrogen films at T=0.7  K. We obtained a rate of pure spatial diffusion of H atoms in the H_{2} films, D^{d}=5(2)×10^{-17}  cm^{2} s^{-1}, which was 2 orders of magnitude faster than that obtained from H atom recombination, the quantity used in all previous work to characterize the mobility of H atoms in solid H_{2}.

Experimental cell with a Fabry-Pérot resonator tuned in situ for magnetic resonance studies of matrix-isolated radicals at temperatures below 1 K.

We describe the design and construction of an experimental cell for the study of free radicals in macroscopically thick films of solidified molecular and rare gases by 128 GHz Electron Spin Resonance (ESR) at temperatures below 1 K. The ESR resonator has an open Fabry-Pérot design, and its frequency can be tuned in situ by adjusting the spacing between the mirrors. The tuning mechanism consists of a piezo positioner and a stainless-steel edge-welded bellows, which can change the resonator frequency by at least 6 GHz.

Dynamic nuclear polarization and ESR hole burning in As doped silicon.

We present an experimental study of the Dynamic Nuclear Polarization (DNP) of Si nuclei in silicon crystals of natural abundance doped with As in the temperature range 0.1-1 K and in a strong magnetic field of 4.6 T.

Formation of Nuclear-Polarized Phases of H Atoms Embedded in Solid H_{2} Films.

We report on an experimental observation of two phases of hydrogen atoms in solid H_{2} films at temperatures of 0.1-0.8 K, characterized by a large enhancement of the nuclear spin polarization compared to that given by Boltzmann statistics (p=0.

ESR study of atomic hydrogen and tritium in solid T and T:H matrices below 1 K.

We report on the first ESR study of atomic hydrogen and tritium stabilized in solid T and T:H matrices down to 70 mK. The concentrations of T atoms in pure T approached 2 × 10 cm (0.60%) and record-high concentrations of H atoms ∼1 × 10 cm (0.