Ultrafast versus Continuous-Wave Plasmonics: How Heat and Hot Electrons Drive Polymerization

Area of Science:

• Plasmonics
• Nanoparticle Chemistry
• Surface Science

Background:

• Hot carriers and heat generation in plasmonic nanoparticles are crucial for plasmon-assisted applications.
• Controlling these effects is vital for chemical processes and device performance.
• Distinguishing hot-electron effects from heat generation under continuous-wave (CW) irradiation is challenging.

Purpose of the Study:

• To investigate hot-electron generation and heat production using polymerization of diazonium salts on gold nanocubes.
• To evaluate the impact of continuous-wave (CW) and femtosecond (fs) irradiation on plasmonic modes.
• To understand the mechanisms driving polymerization under different excitation conditions.

Main Methods:

• Utilized gold nanocubes for plasmonic studies.
• Employed continuous-wave (CW) and femtosecond (fs) irradiation.
• Analyzed polymerization of diazonium salts as a probe for hot-electron and heat effects.
• Investigated polarization-dependent polymerization at plasmonic hot spots.

Main Results:

• Continuous excitation of the quadrupole plasmonic mode drives hot-electron-mediated polymerization.
• CW excitation of the dipole mode leads to chaotic growth driven by lattice heat.
• Femtosecond excitation of the dipole mode results in controlled polymerization at hot spots due to synergistic hot-electron and vibrational heating effects.
• Polymerization initiates at nanocube corners and accelerates at anchoring sites.

Conclusions:

• Femtosecond irradiation offers precise control over plasmonic-driven chemical reactions.
• Understanding the interplay of hot electrons and lattice heating is key for optimizing plasmonic applications.
• This work provides insights into ultrafast processes in nanoparticles for designing efficient chemical reactions and optoelectronic devices.