- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enhancement of photocatalytic activity by femtosecond-laser induced periodic surface structures of Si
摘要： Laser induced periodic surface structures (LIPSS) represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography. This method is much simpler and cost effective. In this work, LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength. Photocatalytic substrates were prepared by depositing TiO2 thin films on top of the structured and unstructured Si wafer. The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres. In first case, the oxygen pressure within the sputtering chamber was chosen to be high (3 × 10–2 mbar) whereas it was one order of magnitude lower in second case (2.1 × 10–3 mbar). In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO2 thin films, respectively. The increase in photocatalytic activity is attributed to the enlargement of effective surface area. In comparative study, the dye decomposition rates of TiO2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington ActivTM.
关键词： photocatalytic dye decomposition,silicon,femtosecond laser pulses,TiO2 thin film,laser induced periodic surface structures,nanoripples
更新于2025-09-23 15:19:57
-
Broad-range ultrafast all-optical red-shifting of EUV surface plasmons: Proof-of-principle and advanced surface nanotexturing in aluminum
摘要： Using aluminum as an example, ultrafast sub-ablative broad-range (EUV-IR) spectral tuning of surface plasmon resonance in metals by IR femtosecond laser pulses was demonstrated by theoretical modeling of prompt surface optics for strongly photoexcited materials and of their surface plasmon-polariton (SPP) dispersion curves, as well as by experimental multi-shot laser imprinting of surface plasmon-polaritons as large-scale regular surface ripples with minimal sub-di?raction periods down to 200 nm. According to laser-pump self-re?ection and charge emission experiments, the key issue in the prompt optical tuning (spectral red-shifting) of EUV surface plasmon resonance in aluminum by the IR laser pulses is related to ultrafast surface charging of its surface via intense electron emission during the laser pump pulse, depleting its surface electron density and simultaneously decreasing its surface/bulk plasma frequencies, at the corresponding negligible surface ablative etching.
关键词： Surface nanoripples,Femtosecond laser excitation,Spectral tuning,EUV surface plasmon resonance,Electronic heating and charging,Aluminum
更新于2025-09-10 09:29:36