链式多Li掺杂分子H(HC==N-Li)nH(n=1~6)的NLO性质及链长依赖性

对链式多Li掺杂体系H(HCN-Li)_nH(n=1~6)的结构与性质进行了研究. 发现随着链长n的增大, 体系中有两类分子出现. 当n=1, 2时, 由于额外电子轨道是空的, 从而形成了Li 盐分子; 而当n=3~6时, 额外电子轨道是占据的, 从而形成了具有大范围额外电子云的多Li电子化物分子. 对于系列体系H(HCN-Li)_nH(n=1~6), 其非线性光学(NLO)性质的依赖性呈现阶梯式增长的规律, 即静态第一超极化率β₀的次序为2179, 2776(n=1, 2)< 5492, 5487(n=3, 4)< 15235, 15377(n=5, 6), 表明增加Li原子掺杂数是提高NLO响应的新途径.

NLO Property for the Multi Li-doped Chain Molecules H(HC=N-Li)nH(n=1-6) and Dependence of Chain Length

The alkali-metal doped system with excess electron is a new kind of potential materials having large non-linear optical(NLO) response. The structures and properties of the multi Li-doped chain molecules H(HCN-Li)_nH(n=1-6) were reported in this paper. Interestingly, with the increasing of chain length n, two kinds of molecules emerge. For n=1 and 2, the Li-salt molecules are formed because the excess electron orbitals are unoccupied. But for n=3-6, excess electron orbitals are occupied and multi-Li electrides with wide-range excess electron cloud are formed. For the multi Li-doped chain system, the dependence on NLO properties is unordinary stepped increase, 2179, 2776(n=1, 2)<5492, 5487(n=3, 4)<15235, 15377(n=5, 6). It demonstrates that multi-Li doping can generate wide-range excess electron cloud and large NLO response. The new knowledge enriches the design ideas for NLO materials.