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Highlights • Time-resolved pump-probe system is used to monitoring the femtosecond laser annealing of indium tin oxide. • The transmittance variation detected by the probe beam gradually increases with increasing machining power. • The 400-nm probe beam is more sensitive than the 800-nm probe beam in measuring curve variation. Abstract In this study, a set of time-resolved pump-probe systems for the real-time monitoring of femtosecond (fs) laser annealing of ITO substrates is established. A pump beam is used as the light source for thermal annealing, and a probe beam is used to monitor the transmittance variation of ITO in real time. Measurement results show that with increasing machining energy, the transmittance variation detected by the probe beam gradually increases. When the laser energy is small, the transmittance changes arithmetically. When the laser energy is sufficient to complete the modification of ITO, the transmittance variation rises suddenly and sharply, indicating that the thermal annealing modification has been completed in the irradiated area. Then, the laser source is shut down to achieve real-time monitoring. Degenerate and non-degenerate pump-probe experimental results indicate that the 400-nm probe beam is more sensitive than the 800-nm probe beam in measuring curve variation because the variation in the ITO transmission spectrum in the 400-nm wave band is greater than that in the 800-nm wave band. Electron backscatter diffraction analysis indicates that the crystallographic directions of ITO after laser annealing are consistent. This shows that the ITO changed from non-crystallized to crystallized after being irradiated by the pump beam, confirming the thermal annealing modification. [ABSTRACT FROM AUTHOR]

Most previous studies have employed surface patterning to improve the performance of lubrication systems. However, few have experimentally analyzed improved effects on friction reduction in SiC mechanical seals by ultra-fast laser pulse texturing. This work applies surface texturing on a non-contact mechanical seal and analyzes the characteristics of the resultant surface morphology. A femtosecond laser system is employed to fabricate micro/nanostructures on the SiC mechanical seal, and generates microscale-depth stripes and induces nanostructures on the seal surface. This work examines the morphology and cross section of the SiC nanostructures that correspond to the different scanning speeds of the laser pulse. Results show that varying the scanning speed enables the application of nanostructures of different amplitudes and widths on the surface of the seal. The friction coefficient of the introduced SiC full-textured seal is about 20% smaller than that of a conventional SiC mechanical seal. Hence, femtosecond laser texturing is effective and enables direct fabrication of the surface micro/nanostructures of SiC seals. This technique also serves as a potential approach to lubricating applications. [ABSTRACT FROM AUTHOR]

Abstract: Periodic nanostructures have played critical roles in key components for optical applications. Femtosecond laser-induced periodic surface structures (FLIPSS) in nano scale on many material surfaces have drawn much attention in recent years. However, the relatively low throughput of the direct inducing process limits its potential in regard to high volume manufacturing. In this study, fast replication of FLIPSS on Polycarbonate (PC) films by gas-assisted a hot embossing process is demonstrated. A selected surface area of a stainless steel thin plate is irradiated by femtosecond laser pulses to form a kind of periodic anti-reflective nanostructure with a period measuring 600–700nm. The stainless plate was then used as a template for the hot embossing process. PC films with periodic nanostructures are then replicated quickly. Compared to the original PC film, at least up to 5% of the reflectivity of the fabricated PC films with nanostructures was reduced. It proves that the gas-assisted hot embossing could procure uniform transcription for anti-reflection PC film with stainless steel template that is irradiated by femtosecond laser pulses. [Copyright &y& Elsevier]

Abstract: A simple and rapid approach for the deposition of platinum (Pt) nanoparticles onto surface of graphene in aqueous solution without reducing agents by femtosecond laser pulses is demonstrated. The formation of graphene-supported Pt in aqueous solution is confirmed by a variety of means such as ultraviolet–visible absorption spectroscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Graphene oxide and PtCl6 2− are simultaneously reduced and Pt nanoparticles can be deposited on the surface of graphene. The presence of Pt on graphene is further confirmed by cyclic voltammetry. The value of electrochemically active surface area of the prepared graphene-supported Pt (58.9 m2 g−1) is higher than most previously reported preparation methods for graphene-supported Pt. For the electrochemical oxidation of methanol, the prepared graphene-supported Pt exhibits a mass activity of 295 mA mg−1 at 0.669 V, which was higher than commercial Pt catalyst and graphene-supported Pt prepared by electrochemical method. [Copyright &y& Elsevier]

Abstract: Multiwalled carbon nanotubes (MWCNTs) supported platinum (Pt) nanoparticles were fabricated in aqueous solution without reducing agents by femtosecond laser. The surface morphological, compositional, and structural characterizations of the prepared Pt/MWCNT were examined using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The results showed that the Pt nanoparticles with about 5–10nm in diameter were well dispersed on the surface of MWCNTs. Cyclic voltammetry was employed to investigate the electrocatalytic activity toward the electrooxidation of glucose in alkaline solution at the Pt/MWCNT. The Pt/MWCNT modified glassy carbon electrode displayed high electrocatalytic ability for the direct electrochemical oxidation of glucose in alkaline solution. At an applied potential of −0.25V vs. Ag/AgCl 3M KCl, the Pt/MWCNT modified electrode exhibited a sensitivity of 0.106AM−1 cm−2 with a linear range up to 2.4mM. This proposed glucose sensor also showed good abilities of anti-interference to acetaminophen, uric acid, fructose, and ascorbic acid. [Copyright &y& Elsevier]

Abstract: Femtosecond laser is employed for the reduction of graphene oxide in aqueous solution without the addition of reducing agents. UV–visible spectra, X-ray diffraction, and X-ray photoelectron spectroscopy confirm the formation of reduced graphene oxide in aqueous solution by the irradiation of femtosecond laser. Tunable extent of deoxygenation on graphene oxide in aqueous solution can be achieved by applying different femtosecond laser irradiation time. With increasing the femtosecond laser irradiation time for the reduction of graphene oxide in aqueous solution, enhanced voltammetric currents with reduced peak-to-peak separations are observed for the Fe(CN)6 4−/Fe(CN)6 3− redox system at the reduced graphene oxide modified electrodes. The electrocatalytic behavior toward the electrooxidation of hydrogen peroxide of the reduced graphene oxide prepared by femtosecond laser is evident from a substantial negative shift of the anodic potential and increased current signal. The present methodology is unique and simple because no reducing agent is required in the reduction process. [Copyright &y& Elsevier]

Abstract: Femtosecond laser was employed to fabricate nanostructured glassy carbon electrode (GCE) for electrocatalysis applications. Atomic force microscopy image demonstrated the formation of femtosecond laser-induced periodic nanostructure on the surface of GCE. The ratio of the intensities of the D band and G band and the surface oxygen concentration changed insignificantly at the GCE after treatment by femtosecond laser. Enhanced voltammetric currents with reduced peak-to-peak separations were observed for the electrochemical reactions of ascorbic acid (AA), dopamine (DA), uric acid (UA), and acetaminophen (AP) using femtosecond laser-induced nanostructured GCE. The femtosecond laser-induced nanostructured GCE demonstrated similar electrochemical behavior to those claimed for carbon nanotube and graphene modified GCEs in AA, DA, UA, and AP oxidation reactions. [Copyright &y& Elsevier]