Laser-induced nucleation of carbon dioxide bubbles

Abstract

A detailed experimental study of laser-induced nucleation (LIN) of carbon dioxide (CO2) gas bubbles is presented. Water and aqueous sucrose solutions supersaturated with CO2 were exposed to single nanosecond pulses (5 ns, 532 nm, 2.4-14.5 MW cm(-2)) and femtosecond pulses (110 fs, 800 nm, 0.028-11 GW cm(-2)) of laser light. No bubbles were observed with the femtosecond pulses, even at high peak power densities (11 GW cm(-2)). For the nanosecond pulses, the number of bubbles produced per pulse showed a quadratic dependence on laser power, with a distinct power threshold below which no bubbles were observed. The number of bubbles observed increases linearly with sucrose concentration. It was found that filtering of solutions reduces the number of bubbles significantly. Although the femtosecond pulses have higher peak power densities than the nanosecond pulses, they have lower energy densities per pulse. A simple model for LIN of CO2 is presented, based on heating of nanoparticles to produce vapor bubbles that must expand to reach a critical bubble radius to continue growth. The results suggest that non-photochemical laser-induced nucleation of crystals could also be caused by heating of nanoparticles.

Polarization independence of laser-induced nucleation in supersaturated aqueous urea solutions

“…11,27 Studies on NPLIN of carbon dioxide bubbles and on filtration of solutions have suggested that transient heating of an impurity nanoparticle can cause rapid expansion and collapse of a vapor bubble, which triggers nucleation. 18,19,27,28 The heating mechanism satisfies several observations that the OKE mechanism does not, including the existence of a distinct laser-power threshold, and the fact that some substances do not exhibit NPLIN despite being likely candidates. 19 Absorption and heating would be expected to show little effect of polarization on direction of product nucleation, although further experiments are required to study this systematically.…”

“…17 Recent experimental results have pointed towards a mechanism based on heating of trace impurity nanoparticles. 18,19 Since the observation of alignment of urea needles along the electric field of the light is central to understanding the mechanism, we have carried out digital imaging of crystal growth during NPLIN of urea.…”

Supersaturation dependence of glycine polymorphism using laser-induced nucleation, sonocrystallization and nucleation by mechanical shock

“…55 As outlined in Section 1, the OKE mechanism for NPLIN, based on laser-induced molecule alignment, has been cast into doubt. 37,[42][43][44][45] An alternative mechanism has been put forward, involving transient heating of particles, leading to formation of cavities and pressure shockwaves in the solution. 43,45 This alternative mechanism for NPLIN is very similar to those believed to operate for ultrasound and mechanical shock, and would account for the similarities in the behaviour shown in Fig.…”

“…42,43 An alternative mechanism to explain NPLIN has been described, based on formation of transient vapour cavities due to heating of impurity particles by the laser light. [43][44][45] The objective of the present work was to explore the supersaturation dependence of polymorphism in glycine solutions using different methods for inducing nucleation. The methods used were pulsed laser light (NPLIN), ultrasound and mechanical shock.…”

Progress in Ultrasonic Cleaning Research

“…2, we show the visualization of acoustic phenomena in the bath ( 28 kHz) under different DO supersaturation. Even under the low-intensity ultrasound irradiation, visible-sized acoustic bubbles appear more densely under higher DO supersaturation, indicating that the population of active bubble nuclei increases as DO supersaturation increases [32,33]. For the lower DO-supersaturation cases ( 0.1 and 1.0), bubbles are entrapped via the primary Bjerknes force [34] that arises from a standing-wave pressure field in the bath.…”