Related Experiment Video
Updated: Jan 10, 2026
12:57
Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection
Published on: October 13, 2017
9.5K
Maximizing the second-harmonic generation response via coordination-induced localization of nonbonding electrons
Jia-Xiang Zhang1,2,3, A-Lan Xu1,2, Yang Chi4
1State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou 350002 China linhua@fjirsm.ac.cn qlzhu@fjirsm.ac.cn.
Chemical Science
|November 26, 2025
Summary
Researchers developed a new method to boost nonlinear optical (NLO) crystal efficiency by localizing nonbonding electrons. This led to KBiP2S6, a sulfide with record-breaking second-harmonic generation (SHG) performance.
Area of Science:
- Materials Science
- Solid-State Physics
- Crystallography
Background:
- Developing nonlinear optical (NLO) crystals with strong second-harmonic generation (SHG) is crucial for laser frequency conversion.
- Chalcogenide NLO materials have shown limited SHG responses, often below 3 × AgGaS2, despite atomic-level design efforts.
- Modulating nonbonding electrons can improve NLO properties, but strategies for maximizing SHG by localizing these electrons are underdeveloped.
Purpose of the Study:
- To explore the relationship between coordination number, nonbonding electron localization, and SHG performance in NLO crystals.
- To design and synthesize novel chalcogenide materials with enhanced SHG responses.
- To elucidate the electronic origins of SHG in these materials and challenge existing models.
Main Methods:
- Theoretical principle: Reducing coordination number enhances nonbonding electron localization and SHG.
- Synthesis of KBiP2S6 (P21, no. 4) crystal.
- Atomic space tessellating analysis and symmetry analysis to determine SHG contributions and favorable crystal symmetries.
Main Results:
- KBiP2S6 exhibits the highest SHG response among sulfides to date, reaching 15 × AgGaS2.
- Atomic space tessellating analysis indicates that sulfur (S) contributes approximately 75% of the SHG, primarily from localized S-3p nonbonding electrons.
- This finding challenges conventional models that emphasize stereochemically active lone pairs (SCALP) and overlook sulfur's role.
- Polar screw axis symmetry was identified as favorable for high-SHG SCALP-based chalcogenides.
Conclusions:
- Reducing coordination number is an effective strategy for localizing nonbonding electrons and enhancing SHG in NLO crystals.
- The study highlights the dominant role of sulfur's nonbonding electrons in driving SHG, necessitating a revision of current theoretical frameworks.
- This work shifts NLO material design towards electronic-level engineering, paving the way for advanced high-performance NLO materials.
Related Concept Videos
02:42Valence Bond Theory
11.1K
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
11.1K
02:45Valence Bond Theory
49.3K
Overview of Valence Bond Theory
49.3K
03:35Hybridization of Atomic Orbitals II
47.6K
sp3d and sp3d 2 Hybridization
47.6K
02:16Resonance and Hybrid Structures
24.8K
According to the theory of resonance, if two or more Lewis structures with the same arrangement of atoms can be written for a molecule, ion, or radical, the actual distribution of electrons is an average of that shown by the various Lewis structures.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
24.8K
03:51Molecular Orbital Theory II
26.8K
Molecular Orbital Energy Diagrams
26.8K
03:02Colors and Magnetism
13.9K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
13.9K