Nanoscale Thermotropic Phase Transitions Enhance Photothermal Microscopy Signals
Abstract
The photothermal heterodyne imaging technique enabled studies of individual weakly absorbing nano-objects in various environments. It uses a photo-induced change in the refractive index of the environment. Taking advantage of the dramatic index of refraction change occurring around a thermotropic liquid crystalline phase transition, we demonstrate a 40-fold signal-to-noise ratio enhancement for gold nanoparticles imaged in 4-Cyano-4'-pentylbiphenyl (5CB) liquid crystals over those in a water environment. We studied the photothermal signal as a function of probe laser polarization, heating power, and sample temperature quantifying the optimal enhancement. This study established photothermal microscopy as a valuable technique for inducing and/or detecting local phase transitions at the nanometer scales.
Keywords
Cite
@article{arxiv.1209.5918,
title = {Nanoscale Thermotropic Phase Transitions Enhance Photothermal Microscopy Signals},
author = {A. Nicholas G. Parra-Vasquez and Laura Oudjedi and Laurent Cognet and Brahim Lounis},
journal= {arXiv preprint arXiv:1209.5918},
year = {2012}
}