Effects associated with bubble formation in optical trapping

Heating of absorbing particles in a liquid medium by an optical trapping be am may lead to bubble formation. Powerful currents, which we identify as du e to Marangoni convection, can be observed in the vicinity. At the micron s ize scale such surface tension effects can be very powerful, whereas normal thermal convection is negligible. Similar effects cause bubbles to be attr acted to regions of higher temperature, providing a very powerful means of trapping bubbles, which are repelled by optical forces in a Gaussian beam. Measurements of the temperature required for bubble formation show that it occurs above the boiling point of the surrounding liquid, in reasonable agr eement with nucleation theories.