研究目的
Investigating the effects of pulse delay between two lasers on plume expansion dynamics in double-pulsed laser ablation with two targets and lasers in a background gas.
研究成果
The expansion distance of the delayed silicon plume is enhanced for delay times between 2 μs and 50 μs compared to single-pulsed laser ablation, due to the density distribution induced by the primary germanium plume. This effect disappears by a delay time of 200 μs, suggesting that the influence of the primary plume diminishes over time. The findings indicate that moderate pulse delays can create new growth fields for nanoparticle formation.
研究不足
The study is limited to the specific conditions of using germanium and silicon targets in a helium background gas at 500 Pa. The effects of different background gases, pressures, or target materials were not explored. Additionally, the study focuses on delay times up to 200 μs, leaving longer delay times unexplored.
1：Experimental Design and Method Selection:
The experiment involved irradiating germanium and silicon targets set parallel to each other with two YAG lasers in a background gas of helium at 500 Pa. The germanium target was irradiated first, followed by the silicon target with a variable delay time, td. The expansion dynamics of the plumes were monitored through plasma emission intensity measured by a gated ICCD camera equipped with a monochromator.
2：Sample Selection and Data Sources:
Silicon and germanium targets were used, with the distance between them set at 9 mm. The plume emission intensity was measured along the line between the laser focusing points on the silicon and germanium targets.
3：List of Experimental Equipment and Materials:
Two Nd:YAG lasers (wavelengths 355 nm for silicon and 266 nm for germanium), a gated ICCD camera, a monochromator, and helium gas as the background medium.
4：Experimental Procedures and Operational Workflow:
The germanium target was irradiated first, followed by the silicon target after a delay time, td. The plume expansion dynamics were observed by measuring the plasma emission intensity over time.
5：Data Analysis Methods:
The position of the plume edge was defined as where the plume intensity was half of its maximum value. The expansion dynamics were analyzed based on the point blast model, fitting the experimental data to the equation R(t) = Ctn.
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