Photo-dissociation on Irradiation with a High Power VUV Laser

用F_2激光研究了二氧化碳与饱和烃体系的光解离及其相关化学反应。对CO_2体系有了新的发现。将激光解离法应用于光学元件的表面加工。在H_2或烃类存在下光还原CO_2等离子化学对于CO_2的再处理可能是有用的，因为发生了高的还原收率。等离子体可以由聚变反应堆的剩余能量和/或聚焦太阳光产生。另一点是连锁反应的可能性。在CO体系中，建议以量子产率大于1.0的方式生成CH_2O。因此，本课题主要研究了VUV激光化学和激光分解化学。(1)光化学主要产物为甲醛和甲烷，少量醇。在H_2压力为40.5MPa、CO_2压力为26.6kPa时，产率为1.5%；在相同压力下，H_2 - CO体系产率为20%。提出了链式反应机理。(2)激光击穿用激光诱导等离子体从H_2、CO_2或CO的混合气体中获得类似的光产物。(3) CO_2的光还原和氢氟碳化合物的氧化。从热醇的形成及其碰撞松弛的角度探讨了反应机理。光学元件表面加工紫外紫外和紫外激光烧蚀已被应用于光学平面元件的加工；甲基丙烯酸、玻璃等。

Photo-dissociation and related chemistry of systems of carbon dioxide and saturated hydrocarbons were studied using an F_2 laser. New findings were obtained for the systems of CO_2. Laser dissociation was applied for surface processing of optical elements.1. Photo-reduction of CO_2 in the presence of H_2 or hydrocarbonsPlasma chemistry may be useful to reprocess CO_2, because a high yield of reduction takes place. Plasma can be generated by surplus energy from a fusion reactor, and/or focusing sun light. Another point is a possibility of a chain reaction. In the system of CO,CH_2O is suggested to from with a quantum yield higher than 1.0. Therefore, VUV laser chemistry as well as laser break down chemistry were studied in this project.(1) PhotochemistryMajor products were formaldehyde and methane, and a small amount of alcohol was detected. The yield was 1.5% under 40.5MPa of H_2 and 26.6kPa of CO_2 and 20% for a system of H_2 and CO under the same pressures. A chain reaction mechanism was suggested.(2) Laser breakdownSimilar photo-products were obtained from a gas mixture of H_2, and CO_2 or CO by laser induced plasma.(3) Photo-reduction of CO_2 and oxidation of hydrofluorocarbonsThe corresponding alcohols weredetected. The reaction mechanisms were discussed based on the formation of hot alcohols and its collisional relaxation.2.Surface processing of optical elementsVUV and UV laser ablation has been applied for processing of optical flat elements ; PMMA,glass, etc.