The Microscopic Origin of Second Harmonic Generation Response: The Spatial Structure of Instantaneous Dipole Moments in Electron Excitation. (1st October 2022)

• Record Type: Journal Article
• Authors: Li, ZhenHua; Zhang, Anmin; Luo, Hong‐Gang
• Is Part Of: Angewandte Chemie. Volume 134:Number 44(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-10-01
• Subjects: Ba4Al11O20F -- Dynamic Dipole Moments -- Functional Building Block -- Nonlinear Optical Materials -- Second Harmonic Generation; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202212125
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: A deep understanding on the crucial factors of the enhanced macroscopic second harmonic generation (SHG) in some deep‐ultraviolet nonlinear optical (NLO) materials is needed to design new NLO materials. Since an optical process relates to the electron excitation and polarization simultaneously, the instantaneous dipole moments and their structures in excitation should be seriously taken account to seek the principal factor in SHG response. In this work, we study the Ba4 B11 O20 F (BBOF), a NLO material, by using the orbital projection technique. From the projected SHG of our theoretic calculation, we recognize the principal dipole moment of the dominant influence on SHG and the relevant atom groups between which the dipole moment is accommodated. With the conclusion that the dipole moment with the most significant influence on SHG is the one between the oxygen–boron polyhedral anion group and barium cation, we predict that Ba4 Al11 O20 F (BAOF) has a comparable SHG response. Abstract : In the NLO materials reported herein, an electron transits from the oxygen atom of the valence state to the barium atom of the conduction state caused by the optical excitation. The charge transition generates instantaneous spatial dipole moments, which contribute to the projected SHG. Depending on the arrangement and ambience of the dipole moments, all microscopic SHG integrate into the macroscopic SHG response.