Intense-field interaction regime with weak laser pulses and localized plasmonic enhancement: Reference-free demonstration by 3rd- and 5th-order infrared spectroscopies

Robert T Mackin; Bar Cohn; Lev Chuntonov; Igor V Rubtsov

doi:10.1063/1.5120531

Intense-field interaction regime with weak laser pulses and localized plasmonic enhancement: Reference-free demonstration by 3rd- and 5th-order infrared spectroscopies

J Chem Phys. 2019 Sep 28;151(12):121103. doi: 10.1063/1.5120531.

Authors

Robert T Mackin¹, Bar Cohn², Lev Chuntonov², Igor V Rubtsov¹

Affiliations

¹ Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, USA.
² Schulich Faculty of Chemistry, and Solid State Institute, Technion, Haifa, Israel.

PMID: 31575172
DOI: 10.1063/1.5120531

Abstract

In bulk materials, intense field interaction is accompanied by undesired nonresonant processes. Plasmonic nanostructures localize enhanced fields exclusively in their vicinity. We report a 4-fold vibrational population inversion between all the excited and the ground states in the molecular monolayer on the surface of gold nanoantennas. Excited population assessment relies on a novel reference-sample-free evaluation of the field enhancement with 5th- and 3rd-order nonlinear infrared spectroscopies and on quantitative modeling of coherent excitation dynamics. This study opens opportunities for precise population control utilizing population inversion for vibrational transitions using weak fields.