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首页> 外文会议>Symposium on In Situ Process Diagnostics and Intelligent Materials Processing held December 2-5, 1997, Boston, Massachusetts, U.S.A. >In situ plasma characterization of laser-ablated Ba_xSr_(1-x)TiO_3
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In situ plasma characterization of laser-ablated Ba_xSr_(1-x)TiO_3

机译：烧蚀Ba_xSr_（1-x）TiO_3的等离子体原位表征

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High speed imaging and emission spectroscopy are used to characterize the plumes generated from the ablation of bulk barium strontium titanium oxide material in vacuum and 30-60 mTorr of O_2 using a pulsed 248-nm laser with fluences ranging from 5-8 J/cm~2. High speed imaging reveals that in vacuum the leading edge of the plume expands normal to the substrate surface with a velocity of 19.7 km/sec. The ratio of distance traveled to the plume's radius is approx 2 at the early stages of the expansion and 3.2 at the later stages near the substrate. Similar observations are observed when the plume expands in 30 mTorr of O_2 for times less than 2.0 mu sec. However, at times greater than 2.0 mu sec the plume's expansion is retarded due to collisional momentum transfer and reactions with the background gas. This effect is more pronounced when the plume expands in 60 mTorr of O_2. Blast wave theory is used to model these results. Time-resolved emission spectroscopy of Ba(I) lines in the 735-770 nm region reveals that the plume' electron temperatures, T_3, in a vacuum expansion range from 18000+-2000 K at 0.1 mu sec to 15000+-1500 K at 2.0 m sec. In contrast, in 30 mTorr of O_2 the values of T_e range from 17000+-2000 K at 0.1 mu sec to 4000+-500 K at 8.0 mu sec. At 0.1 mu sec the plume's electron density is estimated as 1.7+-0.4x10~(17) cm~(-3) in both vacuum and 30 mTorr of O_2. We also determine the Stark broadening of the Ba(I) line at 746 nm to be 0.5+-0.1 A at an electron temperature of 1 eV and an electron density of 10~(17) cm~(-3).
机译：高速成像和发射光谱用于表征在真空和30-60 mTorr的O_2中使用248nm脉冲激光烧蚀大块钡锶钛氧化物材料时产生的羽流，注量范围为5-8 J / cm〜 2。高速成像显示，在真空中，羽流的前缘垂直于基材表面以19.7 km / sec的速度扩展。在膨胀的早期阶段，行进距离与羽流半径的比值约为2，而在基板附近的后期阶段则为3.2。当羽流在30 mTorr的O_2中膨胀小于2.0毫秒的时间时，也会观察到类似的观察结果。但是，在大于2.0毫秒的时间，由于碰撞动量传递以及与背景气体的反应，羽流的膨胀受到了阻碍。当羽流在O_2的60 mTorr中膨胀时，这种效果更加明显。爆炸波理论用于对这些结果进行建模。 Ba（I）线在735-770 nm区域内的时间分辨发射光谱显示，羽流的电子温度T_3在0.1毫秒的18000 + -2000 K真空扩展到15000 + -1500 K的真空膨胀范围内2.0毫秒相反，在O_2的30 mTorr中，T_e值的范围从0.1毫秒的17000 + -2000 K到8.0毫秒的4000 + -500K。在真空和30 mTorr的O_2下，羽流的电子密度在0.1微秒时估计为1.7 + -0.4x10〜（17）cm〜（-3）。我们还确定了在电子温度为1 eV和电子密度为10〜（17）cm〜（-3）时，Ba（I）线在746 nm处的Stark展宽为0.5 + -0.1A。

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