Abstract-Near-Field Infrared Pump–Probe Imaging of Surface Phonon Coupling in Boron Nitride Nanotubes

Leonid Gilburd†, Xiaoji G. Xu†‡, Yoshio Bando§, Dmitri Golberg§, and Gilbert C. Walker*†

† Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada

‡ Department of Chemistry, Lehigh University, 6 East Packer Avenue, Bethlehem, Pennsylvania 18015, United States

§ National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan

J. Phys. Chem. Lett., 2016, 7, pp 289–294

DOI: 10.1021/acs.jpclett.5b02438

Publication Date (Web): January 4, 2016

Copyright © 2016 American Chemical Society

*E-mail: gwalker@chem.utoronto.ca.

http://pubs.acs.org/doi/abs/10.1021/acs.jpclett.5b02438

Surface phonon modes are lattice vibrational modes of a solid surface. Two common surface modes, called longitudinal and transverse optical modes, exhibit lattice vibration along or perpendicular to the direction of the wave. We report a two-color, infrared pump-infrared probe technique based on scattering type near-field optical microscopy (s-SNOM) to spatially resolve coupling between surface phonon modes. Spatially varying couplings between the longitudinal optical and surface phonon polariton modes of boron nitride nanotubes are observed, and a simple model is proposed.