Nanoparticle mediated photodistruption [i.e. photodisruption]
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We present experimentally determined photodisruption enhancement of 50 nm gold spheres irradiated with 780 nm 180 fs pulses using a pump-probe scattering system. Our results indicate a 300 nm cavitation bubble threshold reduction of 31 times when compared to an ultra-pure water base control solution. We utilize a method of matching time between bubble initiation in a continually circulated nanoparticle solution with theoretical focal volume size dependent time between particle-focal volume collision events based on simple particle kinetics. We propose the observed photodisruption is due to electrostatic particle ablation kinetics due to electron photoemission. We apply the Fowler-Dubridge theory for photoemission to nanospheres experiencing strong near-field enhancement to describe particle electric fields induced by non-zero particle charge densities resulting from emitted electrons. An apparent ultra-energy efficient photodisruption mechanism results from multiphoton emission processes in the sub 100 femtosecond pulse regime exceeding typical methods utilizing explosive boiling. In the process of explaining experimental results, we develop a near complete picture of nanoparticle mediated photodisruption as a function of identified relevant system non-dimensional groups and particle enhancement. These results may be used to guide the selection of laser and particle parameters for imaging and different photodisruption regimes.