  Plasmonic microbubbles produced by laser irradiated gold nanoparticles (GNPs)
in various liquids have emerged in numerous innovative applications. The
nucleation of these bubbles inherently involves rich phenomena. In this paper,
we systematically investigate the physicochemical hydrodynamics of plasmonic
bubbles upon irradiation of a continuous wave (CW) laser on a GNP decorated
sample surface in ferric nitrate solution. Surprisingly, we observe the direct
formation of well-defined micro-domes on the sample surface. It reveals that
the nucleation of a plasmonic bubble is associated with the solvothermal
decomposition of ferric nitrate in the solution. The plasmonic bubble acts as a
template for the deposition of iron oxide nanoparticles. It first forms a rim,
then a micro-shell, which eventually becomes a solid micro-dome. Experimental
results show that the micro-dome radius Rd exhibits an obvious dependence on
time t, which can be well interpreted theoretically. Our findings reveal the
rich phenomena associated with plasmonic bubble nucleation in a thermally
decomposable solution, paving a plasmonic bubble-based approach to fabricate
three dimensional microstructures by using an ordinary CW laser.
