Effective Electron Temperature Measurement Using Time-Resolved Anti-Stokes Photoluminescence

Area of Science:

• Nanophotonics
• Ultrafast Spectroscopy
• Materials Science

Background:

• Anti-Stokes photoluminescence in metal nanoparticles indicates internal temperature.
• Previous methods extracted temperature from gold nanoparticles under continuous-wave illumination.
• Extending temperature measurement to pulsed illumination is crucial for studying ultrafast dynamics.

Purpose of the Study:

• To extend anti-Stokes thermometry to pulsed illumination.
• To introduce pump-probe anti-Stokes spectroscopy for measuring ultrafast dynamics.
• To investigate electron heating and cooling dynamics in gold nanoparticles.

Main Methods:

• Utilized anti-Stokes photoluminescence from gold nanoparticles under pulsed laser excitation.
• Developed and applied pump-probe anti-Stokes spectroscopy.
• Achieved subpicosecond time resolution to capture ultrafast electron dynamics.

Main Results:

• Measured an effective electron temperature of approximately 10^3 K in gold nanoparticles.
• Resolved ultrafast electron population dynamics with subpicosecond resolution.
• Observed electron heating and cooling within picoseconds.
• Found the highest apparent temperature occurred 0.6 ps before the maximum extinction signal change.

Conclusions:

• Pump-probe anti-Stokes spectroscopy is a powerful tool for probing ultrafast electron dynamics in nanoparticles.
• The technique provides insights into the temporal evolution of electron temperature and energy relaxation pathways.
• This method opens new avenues for studying transient phenomena in nanomaterials with high temporal precision.