Two-photon luminescence and second harmonic generation from gold micro-plates

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Micron-sized gold plates are of interest for their unique optical properties.
• Understanding their optical responses to external stimuli is crucial for applications.

Purpose of the Study:

• To synthesize micron-sized gold plates using a green chemistry approach.
• To investigate the two-photon luminescence (TPL) and second harmonic generation (SHG) of these gold plates.
• To analyze the dependence of TPL and SHG on excitation laser wavelength and polarization.

Main Methods:

• Synthesis of gold plates via reduction of chloroauric acid with lemongrass extract.
• Characterization of optical properties using two-photon luminescence (TPL) and second harmonic generation (SHG) spectroscopy.
• Systematic variation of excitation laser wavelength and polarization.

Main Results:

• TPL and SHG intensity are dependent on excitation wavelength and polarization.
• TPL intensity generally decreases with increasing wavelength, with a notable peak around 820-840 nm.
• SHG intensity increases with redshift in excitation wavelength.
• TPL intensity at the gold plate edge correlates with the angle between edge orientation and excitation polarization, increasing from 0° to 90°.

Conclusions:

• Lemongrass extract provides a viable method for synthesizing gold plates with tunable optical properties.
• The optical responses (TPL and SHG) of gold plates can be controlled by manipulating excitation parameters.
• Findings offer insights into the fundamental optical behavior of anisotropic plasmonic nanostructures.