Exploring the phase explosion of water using SOM-mediated micro-bubbles

Abstract

We study the growth of a homogeneously nucleated micro-bubble amidst convective flows in water superheated close to the critical point.

In situ self-assembly and photopolymerization for hetero-phase synthesis and patterning of conducting materials using soft oxometalates in thermo-optical tweezers

“…It is known from the literature that at elevated temperatures, heptamolybdate converts into MoO 3 . 35,[44][45][46] For our case, the temperature at the reaction point is estimated to be around 350 1C, 38 which converts the heptamolybdate to MoO 3 , and thus explains the presence of MoO 3 , as we show in Fig. 5(c).…”

“…We anticipated that we could observe direct polymerization due to the action of the trapping laser for the following reason -it is known that a SOM absorbs 1064 nm laser light and goes to the excited state (Mo VI to Mo VI *). This excited state species would oxidize pyrrole/aniline and itself get reduced to the Mo V state, due to the high temperatures (around 350 1C, depending on the laser power 38 ) prevalent near the base of the micro-bubble which is also the focal spot of the laser. Mo V is further reduced to Mo IV , which leads to the completion of the polymerization process.…”

“…While we do not measure the temperature at the laser focal spot directly, we use the fact that water cannot exist as a fluid at temperatures higher than 647 K (374 1C). 38 We then carry out a numerical simulation where we solve the heat equation to predict the size of the bubble at a certain temperature of the hot spot, which we then match with experiments where we measure the size of the bubble at different laser powers. 38 Thus, we are able to obtain a conversion between laser power and temperature of the hot spot, and can set the laser power to a certain optimum value to attain a particular bubble size for a preferred pattern dimension.…”

“…38 We then carry out a numerical simulation where we solve the heat equation to predict the size of the bubble at a certain temperature of the hot spot, which we then match with experiments where we measure the size of the bubble at different laser powers. 38 Thus, we are able to obtain a conversion between laser power and temperature of the hot spot, and can set the laser power to a certain optimum value to attain a particular bubble size for a preferred pattern dimension. Now, the high temperature of the hot spot leads to the conversion of heptamolybdate to the metal oxides in the bubble vicinity.…”

Self-assembly and complex manipulation of colloidal mesoscopic particles by active thermocapillary stress

“…The absorptive surfaces (typically a standard glass coverslip which forms the bottom surface of the chamber or a microscope slide which forms the top surface of the chamber) are attached to each other by double sided sticky tape. In both cases, the temperature of the hot spot would vary between 373K (the threshold for bubble formation) to 644K -the latter corresponding to the critical temperature for water after which it cannot exist as a liquid with the surface tension tending to zero [39]. The temperature of the hot spot can be modified by changing the laser intensity incident on it, which we typically achieve by changing the laser power.…”