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In this study, density functional theory calculations reveal how boron group ions M^+(M = B, Al, Ga, In, and Tl) directly convert carbon and methane into ethylene at room temperature. M^+ reacts with the carbon atom to form the cation MC^+. Then, the reaction of MC^+ with methane leads to the cleavage of metal-carbon bond and the formation of CH2CH2 through C-C coupling, with the ion M^+ serving as a leaving group. The cycle then begins again. The mechanism of C/CH4 system catalyzed by five ion types is investigated herein, and the reasons for the different reactivity of five ion types are determined. The moderate strength of the Al^+-C bond results in Al^+ being the only appropriate catalyst of M^+(M?=?B, Al, Ga, In, and Tl) that can catalyze methane and carbon into ethylene. 相似文献
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阿秒科学是驱动超强超快激光往高平均功率和短脉冲宽度方向快速发展的动力之一.本文针对高重复频率阿秒光源的实际需求,开展了基于国产Yb:CaYAlO4晶体的再生放大理论和实验研究.在理论研究中,根据Yb:CaYAlO4晶体的热透镜计算结果,设计了热稳定性良好的模式可调再生腔;并对晶体π和σ偏振的放大输出能量和光谱进行计算.在此基础上,开展了Yb:CaYAlO4晶体不同偏振性质的再生放大实验研究.在晶体π偏振的实验中,获得了平均功率16.1 W、单脉冲能量1.61 mJ、光谱中心波长1030 nm、光谱半高全宽16 nm的放大输出,压缩后的激光脉冲宽度为149 fs,压缩效率为92.1%,峰值功率大于9.5 GW.在σ偏振获得了平均功率28.7 W、单脉冲能量2.87 mJ、光谱中心波长1037 nm、光谱半高全宽11 nm的放大输出,压缩后的激光脉冲宽度为178 fs,压缩效率为91.5%,峰值功率大于14.2 GW,光束质量因子M2 <1.2.以上研究结果实现了目前Yb:CaYAlO4... 相似文献
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