Lithium atom population transfer by population trapping in a chirped microwave pulse

Using a time-dependent multilevel approach, we demonstrate that lithium atoms can be transferred to states of lower principle quantum number by exposing them to a frequency chirped microwave pulse. The population transfer from n = 79 to n = 70 states of lithium atoms with more than 80% efficiency is achieved by means of the sequential two-photon △n=-1 transitions. It is shown that the coherent control of the population transfer can be accomplished by the optimization of the chirping parameters and microwave field strength. The calculation results agree well with the experimental ones and novel explanations have been given to understand the experimental results.

微波一锅法合成2-硫代喹唑啉二酮衍生物

以靛红酸酐、伯胺、二硫化碳三组分微波一锅法合成了标题化合物，产物结构经IR，^1HNMR，ESI-MS确认。该方法以低毒易得原料高效高产率合成了标题化合物，相比传统方法提高了产率，缩短了反应时间，总收率均在90％以上．总反应时间20-30min。