Femtosecond Laser Ablation Of Gold Research Articles

Comparison of Femtosecond Laser Ablation of Gold and Nickel

The ablation of gold and nickel with a single exposure to 80-fs laser pulses with a moderate intensity (1012–1013 W/cm2) is studied by intereference microscopy. The reflection coefficients were measured, and the threshold values of thermomechanical ablation were determined from the absorbed energy rate. The crater morphology and the dependence of their depth on the rate of the laser-pulse energy are studied.

Femtosecond laser ablation of gold interdigitated electrodes for electronic tongues

Abstract Electronic tongue (e-tongue) sensors based on impedance spectroscopy have emerged as a potential technology to evaluate the quality and chemical composition of food, beverages, and pharmaceuticals. E-tongues usually employ transducers based on metal interdigitated electrodes (IDEs) coated with a thin layer of an active material, which is capable of interacting chemically with several types of analytes. IDEs are usually produced by photolithographic methods, which are time-consuming and costly, therefore, new fabrication technologies are required to make it more affordable. Here, we employed femtosecond laser ablation with pulse duration of 50 fs to microfabricate gold IDEs having finger width from 2.3 μm up to 3.2 μm. The parameters used in the laser ablation technique, such as light intensity, scan speed and beam spot size have been optimized to achieve uniform IDEs, which were characterized by optical and scanning electron microscopy. The electrical properties of gold IDEs fabricated by laser ablation were evaluated by impedance spectroscopy, and compared to those produced by conventional photolithography. The results show that femtosecond laser ablation is a promising alternative to conventional photolithography for fabricating metal IDEs for e-tongue systems.

Nanoparticle plume dynamics in femtosecond laser ablation of gold

This paper describes some recent results on femtosecond laser ablation of gold. We have studied both the fast vapour/plasma and slow nanoparticle plumes using Langmuir probe, time-resolved ICCD imaging and time-resolved optical absorption measurements. The nanoparticle plume dynamics was analysed by comparing the optical emission absorption measurements with an adiabatic isentropic model of ablation plume expansion, leading to an estimate of the amount of material in the nanoparticle plume.

Enhanced Stability of Gold Colloids Produced by Femtosecond Laser Synthesis in Aqueous Solution of CTAB

Femtosecond laser ablation of gold in an aqueous solution of cetyl trimethylammonium bromide (CTAB) is shown to produce nanoparticle suspensions with superior colloidal stability compared to other surfactants, with shelf lives exceeding 2 months even at low concentrations of CTAB, below 1 mM. CTAB also helps control nanoparticle size with mean diameters of 6.3, 5.6, and 4.7 nm obtained in 0.1, 0.5, and 1 mM concentrations of CTAB respectively, compared to 11.9 nm obtained in pure deionized water under same ablation conditions. The size distributions produced with low concentrations of CTAB are comparable to those produced by other surfactants, typically used at high concentrations.

Investigation of nanoparticle generation during femtosecond laser ablation of metals

The production of nanoparticles via femtosecond laser ablation of gold and copper is investigated experimentally involving measurements of the ablated mass, plasma diagnostics, and analysis of the nanoparticle size distribution. The targets were irradiated under vacuum with a spot of uniform energy distribution. Only a few laser pulses were applied to each irradiation site to make sure that the plume expansion dynamics were not altered by the depth of the laser-produced crater. Under these conditions, the size distribution of nanoparticles does not exhibit a maximum and the particle abundance monotonously decreases with size. Furthermore, the results indicate that two populations of nanoparticles exist within the plume: small clusters that are more abundant in the fast frontal plume component and larger particles that are located mostly at the back. It is shown that the ablation efficiency is strongly related to the presence of nanoparticles in the plume.

The emission of atoms and nanoparticles during femtosecond laser ablation of gold

Abstract The properties of laser ablated plumes produced in high vacuum by 100 fs Ti:sapphire pulses from a gold solid target were studied. Optical emission spectroscopy showed that the plume was formed by both atomic and non-atomic species in the whole investigated laser intensity range (1012–1013 W/cm2), while atomic force microscopy analysis of deposits carried out at room temperature revealed the nanometric size of the non-atomic component, with a mean particle radius of tens of nanometers.

Femtosecond laser ablation of gold in water: influence of the laser-produced plasma on the nanoparticle size distribution

Femtosecond laser radiation has been used to ablate a gold target in pure deionized water to produce gold colloids. The dimensional distribution of nanoparticles is characterized by the simultaneous presence of two distinct particle populations: one with low dispersion, having a mean particle size of 5–20 nm, and one with high dispersion, having a much larger particle size. By changing the target position with respect to the radiation focus, we study the influence of the plasma formed after the laser pulse in front of the target, during nanofabrication process. We show that the most intense plasma is produced by positioning the target slightly before the geometric focal point. Here, the plasma intensity was found to correlate with the amount of ablated material as well as with the mean size of nanoparticles associated with the second, highly dispersed, distribution of nanoparticles; this suggests the involvement of plasma-related processes in the ablation of material, and the formation of relatively large particles. The thermal heating of the target by the plasma, and its mechanical erosion by the collapse of a plasma-induced cavitation bubble are discussed as possible ablation mechanisms. The gold nanoparticles produced in ultrapure water are of importance for biosensing applications.

Synthesis of colloidal nanoparticles during femtosecond laser ablation of gold in water

Femtosecond laser radiation has been used to ablate a gold target in pure deionized water to produce colloidal gold nanoparticles. We report evidence for two different mechanisms of material ablation in the liquid environment, whose relative contributions determine the size distribution of the produced particles. The first mechanism, associated with thermal-free femtosecond ablation, manifests itself at relatively low laser fluences F<400 J/cm2 and leads to very small (3–10 nm) and almost monodispersed gold colloids. The second one, attributed to the plasma-induced heating and ablation of the target, takes place at high fluences and gives rise to a much larger particle size and broad size distribution. The fabricated nanoparticles exhibit plasmon-related optical absorption peak and are of significance for biosensing applications.