Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow 119991, Russia.
Phys Chem Chem Phys. 2019 Mar 6;21(10):5771-5779. doi: 10.1039/c8cp04518f.
It is shown theoretically that the mechanism of the rapid coagulation of metal nanospheres into a nanowire in a quantum vortex proposed by E. B. Gordon et al. (Low Temp. Phys., 2010, 36, 590) could not be realized, due to the enormous heat release expelling the nanospheres from the vortex. Also, Gordon's hypothesis on nanowire formation in quantum vortices contradicts the observations that nanowires form above the λ-point (where no quantum vortices exist) and on superfluid helium's surface (parallel to it), which is always perpendicular to the quantum vortices. The nanowire formation process in bulk and dropwise liquid helium is described as a special case of aggregation controlled by diffusion in an external electric field. The nanosphere charging occurs due to the thermoelectric emission from their overheating and also laser ablation. The charged nanospheres attract neutral ones to minimize the electrostatic energy and are also attracted to elevations (field concentrators) on the conductive surfaces surrounding the experimental volume. Both processes lead to nanowire formation and drift prevails over diffusion in both cases. The described mechanism leads to the formation of self-similar anisometric structures in agreement with experimental data.
理论表明，E. B. 戈登等人提出的金属纳米球在量子涡旋中快速凝结成纳米线的机制（低温物理，2010 年，36，590）不可能实现，因为巨大的热量释放会将纳米球从涡旋中排出。此外，戈登关于量子涡旋中纳米线形成的假设与观察结果相矛盾，即纳米线形成于 λ 点（不存在量子涡旋的地方）和超流氦表面（与之平行），而超流氦表面总是垂直于量子涡旋。块状和滴状液氦中的纳米线形成过程被描述为在外部电场中扩散控制的聚集的特殊情况。纳米球的充电是由于过热的热电子发射以及激光烧蚀引起的。带电纳米球吸引中性纳米球以最小化静电能，并且还被吸引到实验体积周围导电表面上的凸起（场集中器）。这两个过程都导致纳米线的形成，并且在这两种情况下，漂移都胜过扩散。所描述的机制导致形成与实验数据一致的自相似各向异性结构。
