Coherent Phonon Dynamics in Plasmonic Gold Tetrahedral Nanoparticle Ensembles

Area of Science:

• Nanotechnology
• Materials Science
• Physical Chemistry

Background:

• Coherent phonon modes in plasmonic nanoparticles are promising for chemical and biological sensing.
• Characterizing these modes typically requires single-particle measurements.
• Recent advances allow synthesis of monodisperse gold tetrahedral nanoparticles with controlled dimensions.

Purpose of the Study:

• To characterize the mechanical and plasmonic responses of size-varying gold tetrahedral nanoparticles.
• To investigate the influence of nanoparticle size and shape on phonon mode frequencies.
• To explore the potential of these nanoparticles in sensing and photonics.

Main Methods:

• Transient absorption spectroscopy of gold tetrahedral nanoparticles in colloidal dispersion.
• Synthesis of highly monodisperse gold tetrahedral nanoparticles with tunable edge lengths and corner sharpnesses.
• Finite-difference time domain (FDTD) and finite element analysis (FEA) calculations.

Main Results:

• Observed oscillations in transient absorption signals corresponding to radial breathing modes.
• Phonon mode frequencies were found to be dependent on nanoparticle edge length and corner truncation.
• Homogeneous quality factor values (24-34) were consistent across the size series.

Conclusions:

• The characterized phonon modes in gold tetrahedral nanoparticles are suitable for ensemble investigations.
• Tunable phonon frequencies offer potential for mass-sensing applications.
• These nanoparticles show promise for plasmon-exciton-coupling photonics schemes.