title: Tip-enhanced THz Raman spectroscopy for local temperature determination at the nanoscale.
abstract: Local temperature of a nanoscale volume is precisely determined by tip-enhanced terahertz Raman spectroscopy in the low temperature range of several tens of degrees. Heat generated by the tip-enhanced electric field is directly transferred to single-walled carbon nanotubes by heat conduction and radiation at the nanoscale. This heating modulates the intensity ratio of anti-Stokes/Stokes Raman scattering of the radial breathing mode of the carbon nanotube based on the Boltzmann distribution at elevated temperatures. Owing to the low-energy feature of the radial breathing mode, the local temperature of the probing volume has been successfully extracted with high sensitivity. The dependence of the temperature rise underneath the tip apex on the incident power coincides with the analytical results calculated by finite element method based on the tip enhancement effect and the consequent steady-state temperature via Joule heat generation. The results show that the local temperature at the nanoscale can be controlled in the low temperature range simply by the incident laser power while exhibiting a sufficiently high tip enhancement effect as an analytical tool for thermally sensitive materials (e.g., proteins, DNA). Graphical Abstract Tip-enhanced THz Raman spectroscopy detects the low frequency Raman mode both in Stokes and anti-Stokes shifts, which precisely reflects the local temperature of the sample volume.
authors.affiliation: Near-field Nanophotonics Research Team, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.|Surface and Interface Science Laboratory, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.|Department of Electronic Chemistry, Tokyo Institute of Technology, Nagatsuta, Kanagawa, 226-8502, Japan.
authors.forename: Maria Vanessa
authors.initials: MV
authors.lastname: Balois
authors.affiliation: Near-field Nanophotonics Research Team, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan. hayazawa@riken.jp.|Surface and Interface Science Laboratory, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan. hayazawa@riken.jp.|Department of Electronic Chemistry, Tokyo Institute of Technology, Nagatsuta, Kanagawa, 226-8502, Japan. hayazawa@riken.jp.|Innovative Photon Manipulation Research Team, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan. hayazawa@riken.jp.
authors.forename: Norihiko
authors.initials: N
authors.lastname: Hayazawa
authors.affiliation: Near-field Nanophotonics Research Team, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.|Surface and Interface Science Laboratory, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
authors.forename: Francesca Celine
authors.initials: FC
authors.lastname: Catalan
authors.affiliation: Near-field Nanophotonics Research Team, RIKEN, The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kawata
authors.affiliation: Department of Electronic Chemistry, Tokyo Institute of Technology, Nagatsuta, Kanagawa, 226-8502, Japan.
authors.forename: Taka-Aki
authors.initials: TA
authors.lastname: Yano
authors.affiliation: Department of Electronic Chemistry, Tokyo Institute of Technology, Nagatsuta, Kanagawa, 226-8502, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hayashi
keywords: Bioanalytical methods; IR spectroscopy/Raman spectroscopy; Laser spectroscopy; Nanoparticles/nanotechnology; Thermal methods