Trigonal selenium is a prototypical one-dimensional (1D) van der Waals (vdW) solid, where covalently bonded helical chains are held together by weaker vdW forces. In this work, we have studied structural transformation from a three-dimensional amorphous phase of non-interacting Se chains into a 1D vdW crystal using x-ray absorption spectroscopy. The crystallization process and establishment of vdW interaction are accompanied by elongation and weakening of covalent Se-Se bonds. We have found a unique signature in the x-ray absorption near-edge structure spectrum that is associated with vdW bonds and can be used to identify the formation of the latter. We believe that a similar approach can be used to study other 1D vdW solids, such as transition-metal trichalcogenides, and particularly stress the usefulness of x-ray absorption spectroscopy to identify vdW bonds.
The formation of a one-dimensional van der Waals selenium crystal from the three-dimensional amorphous phase: A spectroscopic signature of van der Waals bonding
Milos Krbal, Alexander V. Kolobov, Paul Fons, Yuta Saito, George Belev, Safa Kasap; The formation of a one-dimensional van der Waals selenium crystal from the three-dimensional amorphous phase: A spectroscopic signature of van der Waals bonding. Appl. Phys. Lett. 17 January 2022; 120 (3): 033103. https://doi.org/10.1063/5.0080133
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