GaSeCl₅O: A Molecular Compound with Very Strong SHG Effect

Area of Science:

• Inorganic Chemistry
• Solid-State Chemistry
• Materials Science

Background:

• Development of novel inorganic molecular compounds with unique structural and optical properties is crucial for advanced applications.
• Polar chiral crystal structures are rare in molecular compounds, yet they are essential for nonlinear optical (NLO) phenomena like second harmonic generation (SHG).

Purpose of the Study:

• To synthesize and characterize a new inorganic molecular compound, GaSeCl5O.
• To investigate the structural, spectroscopic, and nonlinear optical properties of GaSeCl5O.
• To evaluate its potential for applications in nonlinear optics.

Main Methods:

• Synthesis of GaSeCl5O from SeO2, SeCl4, and GaCl3.
• X-ray structure analysis (single crystal and powder).
• Thermogravimetry, infrared (IR), and Raman spectroscopy.
• Second Harmonic Generation (SHG) measurements.
• Density Functional Theory (DFT) calculations.

Main Results:

• GaSeCl5O was synthesized in quantitative yield with a unique structure featuring a tetrahedrally coordinated Ga atom and a pseudo-tetrahedrally coordinated Se atom, bridged by oxygen.
• The compound crystallizes in the rare polar chiral space group P61.
• GaSeCl5O exhibits an exceptionally strong SHG signal (10x KDP intensity) in the visible spectrum (480-700 nm), attributed to its phase matchability and a large molecular dipole moment (8.3 D).

Conclusions:

• GaSeCl5O is a novel inorganic molecular compound with a rare polar chiral structure.
• The compound possesses one of the strongest SHG effects observed in inorganic molecular materials, surpassing KDP.
• Its remarkable nonlinear optical properties suggest significant potential for applications in photonics and optoelectronics.