Stability of micron-sized spheres formed by pulsed laser ablation of metals in superfluid helium and water

It has been shown that micrometer-sized balls, resulting from the condensation of products of laser ablation of fusible metals in both superfluid helium and water, are in the state of strong internal tension counterbalanced by external compression. By radiation-induced or chemical damage to the integrity of their surface, they break up, ejecting a plurality of nanoparticles. The empty shells of the microspheres, which nonetheless remain intact, are identical to the “hollow spheres” of unclear origin that have been observed previously under laser ablation in usual liquids. The metastability of the microparticles produced by ablation in a liquid should be taken into consideration in their use in engineering and medicine.