  We report experiments that show rapid crystallization of colloids tethered to
an oil-water interface in response to laser illumination. This light-induced
transition is due to a combination of long-ranged thermophoretic pumping and
local optical binding. We show that the flow-induced force on the colloids can
be described as the gradient of a potential. The nonequilibrium steady state
due to local heating thus admits an effective equilibrium description. The
optofluidic manipulation explored in this work opens novel ways to manipulate
and assemble colloidal particles
