09:15 〜 09:30
▼ [19a-H116-2] An all-optical method for determining temperature at the nanoscale via tip-enhanced THz-Raman spectroscopy
キーワード：THz-Raman spectroscopy,nanophotonics,thermal methods
Scientific research is constantly moving from the “microscale” to the “nanoscale”. In order to probe and study nano-sized samples, signal enhancing analytical techniques with high chemical sensitivity and spatial resolution have been developed, such as tip-enhanced Raman scattering (TERS). Generating an enhanced field at nanoscale volumes, however, also means that undesired laser-induced heating is enhanced, especially near the vicinity of the tip apex as in the case of TERS, which has only been reported by several groups [1-3]. Therefore, it is important to be able to determine the temperature at the sample and the temperature changes that occur, particularly in the low temperature regime (< 100 C) for proper data analysis and prevention of tip and sample damage. Here we present an all-optical method called tip-enhanced THz-Raman spectroscopy (TE-THzRS, THz-Raman < 200 cm^-1) for determining temperatures at the nanoscale [1]. In this contribution, we studied the heat transferred from the tip-enhanced electric field to single walled carbon nanotubes (CNTs) via heat conduction and radiation. Heating modulates the intensity ratio of anti-Stokes/Stokes Raman – in photon count rates – scattering of the radial breathing mode (RBM) of the CNTs and the sample temperature (T) following the Boltzmann distribution. Aside from heating, the plasmon resonance of the tip can affect . Considering all these factors, the local temperature is successfully extracted with high sensitivity due to the RBM’s low energy feature. Advantages of using an all-optical technique to determine the temperature are 1) temperature can be extracted during data acquisition and 2) tip preparation is not needed especially for techniques that determine the temperature through desorption of molecules at the tip apex.