Search results for "Laser ablation"
showing 10 items of 97 documents
Transport and magnetic properties of La1−xCaxMnO3-films (0.1<x<0.9)
2000
Abstract By laser ablation we prepared thin films of the colossal magnetoresistive compound La1−xCaxMnO3 with doping levels 0.1 10 13 Ω have been measured with an electrometer setup. While the transport data indicate polaronic transport for the metallic samples above the Curie temperature the low-doped ferromagnetic insulating samples show a variable range hopping like transport at low-temperature.
Bimodal velocity distribution of atoms released from nanosecond ultraviolet laser ablation
2005
We have investigated the velocity distributions of atoms released from a metallic gadolinium surface by UV laser ablation. The fluences of the nanosecond laser pulses were chosen for a pure release of neutrals and at a higher fluence level for the release of both neutrals and ions. In both cases a thermal Maxwell-Boltzmann slope has been observed for the low velocities, whereas for high velocities strong deviations from a thermal distribution have been seen. The observed velocity distribution has been explained by a bimodal structure including a thermal phase and a shockwave driven ``blow-off'' phase.
Characterization of laser ablation of copper in the irradiance regime of laser-induced breakdown spectroscopy analysis
2014
Abstract The LIBS signal depends both on the ablated mass and on the plasma excitation temperature. These fundamental parameters depend in a complex manner on laser ablation and on laser–plasma coupling. As several works in the literature suggest that laser ablation processes play a predominant role compared to plasma heating phenomena in the LIBS signal variations, this paper focuses on the study of laser ablation. The objective was to determine an interaction regime enabling to maximally control the laser ablation. Nanosecond laser ablation of copper at 266 nm was characterized by scanning electron microscopy and optical profilometry analysis, in air at 1 bar and in the vacuum. The laser …
Surface modifications induced by nanosecond pulsed Nd:YAG laser irradiation of metallic substrates
2006
International audience; Substrate surface preparation is a key step in coating deposition process. In recent years, pulsed laser cleaning has emerged as a possible technique to challenge the traditional preparation methods (based on degreasing and eventually grit-blasting). The laser operated at short-pulse mode offers high cleaning efficiency and therefore has been largely used. In a specific process named PROTAL®, a nanosecond pulsed laser is introduced to prepare the surface simultaneously to thermal spraying, with the purpose of eliminating the contaminants and generating favorite surface conditions for coating deposition. This study aims at clarifying some fundamental aspects of nanose…
Resistive switching behaviour in ZnO and VO 2 memristors grown by pulsed laser deposition
2014
The resistive switching behaviour observed in microscale memristors based on laser ablated ZnO and VO 2 is reported. A comparison between the two materials is reported against an active device size. The results show that devices up to 300 × 300 μm 2 exhibit a memristive behaviour regardless of the device size, and 100 × 100 μm 2 ZnO-based memristors have the best resistance off/on ratio.
Application of sol-gel and laser evaporation methods to obtain thin gas sensitive films
2005
New type resistive/capacitative gas sensitive structures were obtained by using a specially prepared substrate- glass, covered by thin conducting In/sub 2/O/sub 3/ layer, cutted into a comb teeth-type electrodes by help of laser beam. Such laser processed gap in the layer of conducting material was a prototype of excellent humidity sensor, especially at high values of relative humidity (RH). Different additional coatings onto a laser processed gap were examined for humidity sensing. Sol-gel, vacuum thermal evaporation and laser evaporation methods were used to obtain a thin layers of different materials.
Ultra-fast-prototyping of PMMA structures for micro-engineering applications: Choosing the right material
2017
Machining of poly(methyl methacrylate) (PMMA) by laser has been extensively studied in engineering research for several applications including microfluidic manufacturing and rapid prototyping. However, very few investigations have taken into consideration the wide range of physico-chemical characteristics of commercially available PMMA that can often affect the quality of the laser-machined structures. These characteristics are often ignored, with many manufacturing publications focusing on a single source of PMMA. To understand the different bonding strengths and laser-cut qualities in the context of our ultra-fast prototyping technique, four types of PMMA have been examined. Molecular wei…
Calcium Carbonate and Phosphate Reference Materials for Monitoring Bulk and Microanalytical Determination of Sr Isotopes
2017
In situ laser ablation analyses rely on the microanalytical homogeneity of reference materials (RMs) and a similar matrix and mass fraction between unknown samples and RMs to obtain reliable results. Suitable carbonate and phosphate RMs for determination of Sr isotope ratios in such materials are limited. Thus, we determined Sr-87/Sr-86 ratios of several carbonate (JCt-1, JCp-1, MACS-1, MACS-3) and phosphate (MAPS-4, MAPS-5, NIST SRM 1400, NIST SRM 1486) international RMs using dissolved samples and two different multi-collector inductively coupled plasma-mass spectrometers (MC-ICP-MS). Our Sr isotope data are in agreement with published data and have an improved measurement precision for s…
Image-Guided Thermal Ablation as an Alternative to Surgery for Papillary Thyroid Microcarcinoma: Preliminary Results of an Italian Experience
2021
PurposeTo report the results of our preliminary experience in treating patients with papillary thyroid microcarcinoma (PTMC) with image-guided thermal ablation, in particular estimating the feasibility, safety and short-term efficacyMaterials and MethodsFrom 2018 patients with cytologically proven PTMC &lt; 10 mm were discussed in a multidisciplinary team and evaluated for feasibility of image-guided thermal ablation. In case of technical feasibility, the three possible alternatives (i.e., image-guided thermal ablation, surgery, and active surveillance) were discussed with patients. Patients who agreed to be treated with image guided thermal ablation underwent radiofrequency (RFA) or la…
Mass-independent analysis of the stable isotopologues of gas-phase titanium monoxide – TiO
2021
More than 130 pure rotational transitions of $^{46}$TiO, $^{47}$TiO, $^{48}$TiO, $^{49}$TiO, $^{50}$TiO, and $^{48}$Ti$^{18}$O are recorded using a high-resolution mm-wave supersonic jet spectrometer in combination with a laser ablation source. For the first time a mass-independent Dunham-like analysis is performed encompassing rare titanium monoxide isotopologues, and are compared to results from high-accuracy quantum-chemical calculations. The obtained parametrization reveals for titanium monoxide effects due to deviations from the Born-Oppenheimer approximation. Additionally, the dominant titanium properties enable an insight into the electronic structure of TiO by analyzing its hyperfin…