研究目的
Investigating the effect of a liquid medium on the roughness and the chemical composition of an ablated, stainless steel target, as well as on various properties of the laser-generated nanoparticles, such as absorption, hardness, and yield.
研究成果
Changing the liquid medium affects both the chemical composition of the solid surface as well as the yield of nanoparticles due to the difference in the elemental species available for various chemical reactions. Plasma is more confined in water than in hexane, allowing for 'blow-off' of the melted layer and leading to a reduced roughness of the target following ablation.
研究不足
The laser energy oscillated between 15–20 mJ/pulse, giving an average energy of ~17 mJ/pulse, due to the low stability of the used laser system. EDAX is a localized technique, carbon is below the limit of detection.
1：Experimental Design and Method Selection:
The ablation experiments were performed using the fourth harmonic (wavelength of 266 nm) of a Nd:YAG laser with a pulse width of 8 nanoseconds and repetition rate of 10 Hz. The laser beam was focused with a 10 cm focal length lens to ablate a stainless steel target immersed in either hexane or distilled water.
2：Sample Selection and Data Sources:
The target was purchased commercially and its composition was analyzed by X-ray fluorescence (XRF) before ablation, while its morphology was diagnosed by both scanning electron microscope (SEM) and atomic force microscope (AFM), while X-ray diffraction (XRD) was used to examine the chemical structure of the surface.
3：List of Experimental Equipment and Materials:
Nd:YAG laser (Continuum PL7010), XRF, SEM, AFM, XRD, Camspec M501 UV-Vis spectrophotometer.
4：Experimental Procedures and Operational Workflow:
The target was manually scanned for 45 minutes. The total liquid height from the bottom of the used ablation chamber was 5 cm, corresponding to a liquid height of 3 cm above the ablation target surface.
5：Data Analysis Methods:
The nanoindentation was applied to measure the nanohardness of these nanoparticle films; the maximum load used was 20.03 mN. Sixteen random positions were selected on each sample to measure the nanohardness due to the lack of the homogeneity across the thin film.
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