Pulsed laser ablation of binary semiconductors: mechanisms of vaporisation and cluster formation

Laser-induced transfer of nanoparticles for gas-phase analysis

“…Preliminary experiments of femtosecond-laser ablation of a sandwich metal film (50-nm gold film with a 20-nm titanium sublayer on a glass substrate) placed at the point of particle ionization were performed to optimize irradiation and detection conditions for the highest ion signal in the MS. A femtosecond-laser fluence of ∼300 mJ∕cm 2 was chosen for irradiating the particles removed from the substrate in the LIFT experiments as it resulted in complete ablation of the gold film by a single pulse with a fairly high ion yield. In the second MS apparatus [21], nanoparticles traveled over a distance of 36 mm toward a repeller grid where they were ablated at a corresponding time delay by 193-nm photons (5-ns pulse of a ArF laser at ∼1 J∕cm 2 ). The produced ions were extracted with a perpendicular geometry and analyzed by a reflectron TOF MS.…”

Co-Doped ZnS Clusters and Nanostructures Produced by Pulsed Laser Ablation

“…More details of the laser ablation mass spectrometers have been given elsewhere. 19,20 Laser ablation of targets with the same composition as above was performed in a pulsed laser deposition (PLD) set up using the fundamental output of a Nd:YAG laser (λ = 1064 nm). The laser beam was directed to the target at normal incidence and was focused by a 58 cm focal length lens to a circular spot of 0.013 cm 2 (measured at 1/e 2 level).…”

“…The ion source and the deflection system of the reflectron TOF MS were designed to detect fast ions in the ablation plasma. Before entering the flight tube of the mass spectrometer, the ion path was adjusted by a pair of deflection plates in order to compensate for their initial velocities optimizing the ion collection efficiency; this enabled equal collection efficiency for all plume ions with kinetic energies up to 50 eV. − The neutral ejected species were analyzed in a linear TOF MS provided with a postionization F 2 excimer laser (λ = 157 nm, E ≤5 mJ). The target surface was placed parallel to the flight axis of the spectrometer at distances in the range of 0.5–2.5 cm; in this way, the mildly focused postionization laser beam could interact with the plume at different distances from the target surface and at different time delays with respect to the ablation pulse.…”

Room Temperature Deposition of Crystalline Nanoporous ZnO Nanostructures for Direct Use as Flexible DSSC Photoanode

“…Expanded gas is then pushed back and compressed. Nanoparticles are reported to be concentrated in the region between plume and buffer gas where the highest supersaturation is reached [ 25 , 26 ] due to the extremely fast quenching rate right after the initial ablation. High spatial localization of nanoparticles leads to three-dimensional fractal aggregations kinetically deposited onto the substrate forming columnar nanostructures suggesting diffusion limited aggregation [ 27 ] is the main factor when cluster formation takes place during PLD plume condensation and deposition.…”