Balanced Second-Order Nonlinear Optical Properties of Adducts CHI·(S) and AsI·(S): A Systematic Survey.

Two isostructural adducts CHI·(S) (1) and AsI·(S) (2) are synthesized by a simple solution method. Both of them crystallize in noncentrosymmetric R3 m, featuring van der Waals interaction linked CHI tetrahedra or SbI trigonal pyramids with crown-like S molecules. Both 1 and 2 show strong SHG responses and phase matchability under either 1.064 or 2.1 μm. The results of DFT calculations indicate that the electron transfer happens from S-3p to I-5p orbitals, and both of them demonstrate indirect band gaps. The NLO effects of 1 and 2 are almost fully contributed from the CHI or AsI units. Compared with AgGaS, their powder laser damage thresholds are ca. 15 and 51 times higher.