Comparison of Vapor Formation of Water at the Solid/Water Interface to Colloidal Solutions Using Optically Excited Gold Nanostructures

Abstract

The phase transformation properties of liquid water to vapor is characterized by optical excitation of the lithographically fabricated single gold nanowrenches and contrasted to the phase transformation properties of gold nanoparticles located and optically excited in a bulk solution system [two and three dimensions]. The 532 nm continuous wave excitation of a single gold nanowrench results in superheating of the water to the spinodal decomposition temperature of 580 ± 20 K with bubble formation below the spinodal decomposition temperature being a rare event. Between the spinodal decomposition temperature and the boiling point liquid water is trapped into a metastable state because a barrier to vapor nucleation exists that must be overcome before the thermodynamically stable state is realized. The phase transformation for an optically heated single gold nanowrench is different from the phase transformation of optically excited colloidal gold nanoparticles solution where collective heating effects dominates and leads to the boiling of the solution exactly at the boiling point. In the solution case, the optically excited ensemble of nanoparticles collectively raises the ambient temperature of water to the boiling point where liquid is converted into vapor. The striking difference in the boiling properties of the single gold nanowrench and the nanoparticle solution system can be explained in terms of the vapor-nucleation mechanism, the volume of the overheated liquid, and the collective heating effect. The interpretation of the observed regimes of heating and vaporization is consistent with our theoretical modeling. In particular, we explain with our theory why the boiling with the collective heating in a solution requires 3 orders of magnitude less intensity compared to the case of optically driven single nanowrench.

Nanoparticles Heat through Light Localization

“…(6) It has been suggested that collective thermal effects are important in explaining the response of such systems. (7)(8)(9)(10)(11) Here we show, however, that collective thermal effects alone are not sufficient to explain the thermal response of these systems. Rather, light trapping by solutions of particles that simultaneously absorb and scatter light results in highly localized heating, an unanticipated effect that, when combined with classical heat transfer, provides an accurate theoretical description of the system.…”

Steam generation in a nanoparticle-based solar receiver

“…However, there is no evidence to support the claim that steam production was caused by nanobubbles, i.e., bubbles were formed on top of heated nanoparticles. It should be noted that the solar intensity employed here was 220 Suns, as a few previous work [17,[37][38][39][40][41] has suggested that nanobubbles were unlikely to be generated under relatively low heat fluxes. For example, both Kotaidis et al [42] and Keblinski et al [43] pointed out that a laser power density equivalent to more than Suns was required to form nanobubbles.…”

Plasmonic Bubbles in n-Alkanes

“…20 Owing to the technological relevance of these microbubbles, the dynamics of their growth and shrinkage has been scrutinized in several investigations. 7,9,12,[22][23][24][25][26] Plasmonic bubble generation is a complex phenomenon, which involves numerous physical processes, such as heat transfer from the nanoparticle to the liquid, supersaturation of the liquid, phase transitions, bubble nucleation, diffusion of gas dissolved in the liquid, evaporation of the liquid and many others. The irradiation of metal nanoparticles immersed in liquid with a continuous laser at resonant wavelength results in plasmonic excitation of the nanoparticles and thereby, in a rapid increase of the temperature of the nanoparticles.…”