|
Title:
|
Nanoparticle mediated photodistruption [i.e. photodisruption] |
|
Author:
|
Haering, Sigfried William |
|
Abstract:
|
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 . |
|
URI:
|
http : / /hdl .handle .net /2152 /ETD -UT -2010 -08 -1795
|
|
Date:
|
2010-12-23 |