Stoichiometry-Modulated Resonant Raman Spectroscopy of WS_2(1–x)Se_2x-Alloyed Monolayer Nanosheets

Abstract

We demonstrate the resonant Raman features of WS 2(1−x) Se 2x -alloyed monolayer (1L) nanosheets are strongly modulated by their stoichiometry. The A excitonic energies of the 1L samples prepared by the vapor transportation (VT) method are greatly tuned from 1.95 to 1.6 eV by the increasing content of selenide as x = 0, 0.1, 0.2, 0.5, 0.7, and 1. These alloyed 1L samples exhibit strong resonant features, with which the intensity and width of the prominent Raman peaks show close dependence on the stoichiometry and the excitation laser wavelengths. The Raman intensity resonances of the WS 2 -like mode (A′ W−S ) and WSe 2 -like mode (E′ W-Se ) modes of the alloyed samples are similar to A′ and E′ of 1L WS 2 and WSe 2 , respectively, but shifted by their excitonic energies. These results would enrich the knowledge of the exciton−phonon interactions of alloyed two-dimensional (2D) semiconductors.

Systematic characterization of adenosine triphosphate response to lung cancer epidermal growth factor receptor missense mutations: A molecular insight into “generic” drug resistance mutations

“…The intermolecular interaction between ATP and mutated residue (i.e., wild‐type or mutant residue) in the kinase–ATP complex system was minimized using the ONIOM‐based QM/MM method. [ 34 ] The system was partitioned into two layers: [ 35,36 ] the ATP molecule and the mutated residue were included in the inner layer and treated with a semiempirical AM1 theory, while the rest of the system was in the outer layer and described using an all‐atomic force field of universal force field (UFF). Hydrogen atoms were used as link atoms to saturate the dangling bonds, and the electrostatic interactions between the two layers were treated in terms of a mechanical embedding scheme to save computational cost.…”