Near-Field Induced Reaction Yields from Nanoparticle Clusters

Abstract

Ultrafast light-induced molecular reactions on aerosolized nanoparticles may elucidate early steps in the photoactivity of nanoparticles with potential impact in fields ranging from chemistry and medicine to climate science. In situ morphology discrimination for nanoparticle streams when measuring light-induced reaction yields is crucial, but lacking. Here, we experimentally demonstrate, using the reaction nanoscopy technique, that proton momenta from deprotonation reactions induced by intense femtosecond pulses exhibit clear, distinguishable signatures for single silica nanospheres and their clusters. Our findings are supported by classical trajectory Monte Carlo simulations. The results demonstrate an in situ single-shot discrimination method between reaction yields from photoinduced processes on single particles and their clusters. We find that the ionization of clusters dominates at sufficiently low intensities, providing an explanation to resolve previously observed discrepancies between experimental data and theoretical treatments, which considered only single nanoparticles.

Three-dimensional Imaging of Nanoplasma by Ion Nanoscopy

“…Their nal energy mainly arises from long-range electrostatic repulsion 22,34 , which occurs over the time scale of picoseconds. It is also worth mentioning that the Coulomb attraction between the fast escaping electrons and the slow ions created on the nanosphere is negligible and has no signi cant effect on the nal ion momenta 22 .…”

“…It is also worth mentioning that the Coulomb attraction between the fast escaping electrons and the slow ions created on the nanosphere is negligible and has no signi cant effect on the nal ion momenta 22 . Since the trajectories of the ions are also hardly affected by the laser electric eld, a relatively simple and straightforward static electrostatic model 34 is then applicable to correlate the ion momentum distribution with the charge distribution on the surface of the nanosphere.…”

“…At very low radiation intensities, much progress has been made experimentally in understanding how the nanostructure affects localized plasmons [15][16][17] , owing to the development of detection solutions for the plasmonic spatial distribution from two-dimensional (2D) planar (such as photoemission electron microscopy and near-eld scanning optical microscopy) to three-dimensional (3D) planes [18][19][20][21][22][23] . However, we cannot apply these technologies to image nanoplasmas generated at high radiation intensities because the underlying physics for plasmons is different from that for plasma generated at high radiation intensities as discussed here.…”

Nanoparticles in analytical laser and plasma spectroscopy – a review of recent developments in methodology and applications

“…As an example, interesting recent fundamental works dealing with the directional emission of electrons and ions from isolated nanoparticles induced by femto-and attosecond laser impulses can be mentioned. 597,598 The combination of nm-scale sampling on sub-fs time scales could open new analytical possibilities for the monitoring of near-eld induced reaction yields on the surface of nanoparticles ("reaction nanoscopy") 599 or for the differentiation of single particles and their dimers based on their plasmonic characteristics, 600 to name just a couple of options.…”

Strong-field control of plasmonic properties in core-shell nanoparticles

“…The source aerosolizes a colloid of nanoparticles that are subsequently dried by a solid-state counter-flow membrane dryer to remove the solvent (water) from the carrier gas (N 2 ). Additional care was taken to minimize the probability of clusters in the nanoparticle beam to prevent an amalgamation of photoelectrons from monomers and clusters [2] by keeping the number density below 10 10 nanoparticles per mL. The in-vacuum beam density was increased using an aerodynamic lens system to focus the gas-phase nanoparticles while a three-stage differentially pumped arrangement removed excess carrier gas in vacuum.…”