Table 1.

Diffusion parameters as determined from the experimental data in Fig. 2.

$\mathrm{\Delta }K$ (Å-1)	$E_a$ (meV)	${\alpha }_0$ (ns−1)
0.22	$32\pm 4$	107 ± 45
0.55	$36\pm 4$	171 ± 72

Extracted diffusion barriers $E_a$ and pre-exponential factors ${\alpha }_0$ for two different momentum transfers $\mathrm{\Delta }K$. The pre-exponential hopping rate ${\mathrm{\Gamma }}_0$ for the diffusion process at 150 K is then ${\mathrm{\Gamma }}_0=\left(1.7\pm 0.6\right)\cdot 10^{11}{\mathrm{s}}^{-1}$