激光烧蚀La~2O~3产生的等离子体的发光光谱研究

用发光光谱法研究了355nm脉冲激光在真空和O~2气氛中烧蚀La~2O~3产生的等离子体的组成和形成过程。对等离子体中La^+离子和LaO的空间和时间分辨发光光谱分析表明,在O~2气氛中LaO有两个生成通道:一是在靶附近的等离子体内直接生成的,另一是由La,La^+与O^2发生氧化反应而生成的。测定了激光能量密度,离靶表面的距离和O~2压力对产物发光的延迟时间和发光强度的影响。此外,还讨论了激光烧蚀La~2O~3诱导产生等离子体的形成和演化机理。

Time-resolved emission spectrometric study on laser ablated plasma from a La~2O~3 target

The composition and the evolution of the 355 nm laser ablated plasma from a La2O3 target both in vacuum and in ambient O2 were investigated by using time - resolved emission spectrometry. Our results show that the excited La * and LaO* are two main emission species. It is suggested that there are two pathways for the formation of LaO* in ambient O2, one is the direct production via laser - target interaction,and the other is the formation via the oxidation of La and La .The dependence of the delay time and the intensity of the emission on the laser fluence, the observation distance away from the target surface, and the ambient O2 pressure were examined. A kinetic model based on the interactions between the ablated species and the ambient O2 is proposed to explain the experimental results satisfactorily. The mechanism of the plasma formation and evolution is also discussed.