Local heating and Raman thermometry in a single molecule
Qiushi Meng, J. B. Zhang, Yao Zhang, Yao Zhang, Weizhe Chu, Wenjie Mao, Yang Zhang, Yang Zhang, Jinlong Yang, Yi Luo, Zhen‐Chao Dong, Jian Hou
Abstract
Because of the nonequilibrium nature of thermal effects at the nanoscale, the characterization of local thermal effects within a single molecule is highly challenging. Here, we demonstrate a way to characterize the local thermal properties of a single fullerene (C 60 ) molecule during current-induced heating processes through tip-enhanced anti-Stokes Raman spectroscopy. Although the measured vibron populations are far from equilibrium with the environment, we can still define an “effective temperature ( T eff )” statistically via a Bose-Einstein distribution, suggesting a local equilibrium within the molecule. With increased current heating, T eff is found to rise up to about 1150 K until the C 60 cage is decomposed. Such a decomposition temperature is similar to that reported for ensemble C 60 samples, thus justifying the validity of our methodology. Moreover, the possible reaction pathway and product can be identified because of the chemical sensitivity of Raman spectroscopy. Our findings provide a practical method for noninvasively detecting the local heating effect inside a single molecule under nonequilibrium conditions.