为了研究C2的演化规律, 采用增强型电荷耦合器件（ICDD）直接成像法, 通过Nd∶YAG激光器烧蚀石墨靶, 使用窄带通滤波片分辨出C2和C+的发射位置, 研究了在不同空气压力条件下, 脉冲激光诱导石墨等离子体中C2和C+的发射特性。当空气气压为10-2Pa和3Pa时, C2发射峰值位于靶材附近, 此时C2的形成主要为靶材的直接发射; 气压增大至50Pa时, 由于气相重组反应加强, 等离子体前端出现另一个C2的发射峰值, 其峰值位置与C+一致,并且其逐渐占C2发射的主导地位, 此时C2的形成主要来源于重组反应, C+发射光强要大于C2; 当气压进一步增大至130Pa时, 气相重组反应增加, 在等离子体前端出现C2的发射强度增强, 在1.3μs之后, C2的发射强度大于C+。结果表明, 随着气压的变化, C2的发射峰值位置和强度发生明显变化。这一结果对碳等离子体沉积碳纳米材料原理研究是有帮助的。

In order to study evolution of C2, emission characteristics of C2 and C+ in graphite plasma were studied through intensified CCD direct imaging method at various air pressures.Graphite plasma was produced by Nd∶YAG laser, the launch positions of C2 and C+ were distinguished through a narrow band-pass filter. At low pressure of 10-2Pa and 3Pa, emission peak of C2 is located near the target and the formation of C2 is mainly generated by direct emission of target material. With the increase of gas pressure to 50Pa, another emission peak of C2 appears at the front of plasma plume due to the enhancement of gas phase recombination reaction. This peak position is consistent with the C+ and then becomes the dominant of C2 emission. The formation of C2 mainly comes from the recombination reaction. The emission intensity of C+ is larger than that of C2. With the increase of pressure to 130Pa, gas phase recombination reaction increases and emission intensity of C2 increases at the front of the plasma. After 1.3μs, the emission intensity of C2 is greater than that of C+. The results show that C2 emission peak position and intensity change significantly with the pressure. The result is helpful for the study of the principle of carbon nanomaterials deposited by carbon plasma.