Surface-enhanced ultrafast two-dimensional vibrational spectroscopy with engineered plasmonic nano-antennas

Area of Science:

• Plasmonics and Nanophotonics
• Infrared Spectroscopy
• Surface-Enhanced Spectroscopy

Background:

• Noble metal nanostructures create strong electric field enhancements (near-fields).
• These enhancements boost spectroscopic signals from small sample quantities like thin films and monolayers.
• Signal amplification is particularly pronounced in nonlinear infrared (IR) spectroscopy.

Purpose of the Study:

• To review advances in nano-antenna arrays for mid-IR measurements.
• To illustrate their application in linear and nonlinear 2D IR spectroscopy.
• To discuss the interplay between plasmonic antennas, light, and molecular excitations.

Main Methods:

• Development of nano-arrays of antenna-like nanostructures.
• Application in linear and nonlinear two-dimensional IR spectroscopy.
• Utilizing time-resolved methods to study light-matter interactions.

Main Results:

• Achieved significant signal gains (10^6 to 10^8) in third- and fifth-order IR spectroscopy.
• Demonstrated enhanced sensitivity to signal localization and excitation coherence.
• Showcased benefits for studying molecular structure and ultrafast dynamics.

Conclusions:

• Plasmonic nanostructures are crucial for enhancing IR spectroscopic sensitivity.
• Nonlinear 2D IR spectroscopy with nanostructures offers powerful insights into molecular behavior.
• This approach advances the study of molecular structure and dynamics at the nanoscale.