2020 Volume 63 Issue 5 Pages 235-238
We introduce the Tribo-Phonon Spectroscopy (TPS) developed to study phonons producing and dissipating at a tip-surface, which consists of an atomic force microscope (AFM) and a quartz-crystal microbalance (QCM). An AFM tip used to apply stresses generated lattice strain on an oscillating MoS2(0001) surface, which dissipated via acoustic phonons. The dissipation energy of the phonons strongly depended on the size of the lattice strain. The motion of the acoustic phonons consisted of a longitudinal mode and a transverse mode, but the occurrence of their phonon modes depended on the crystallographic direction, which reflects the atomic arrangement of the MoS2(0001) surface. In addition, we report that the acoustic phonons produced in MoS2 islands are confined within MoS2 islands smaller than the mean free path (MFP) of the phonons.