  We demonstrate Raman sideband thermometry of single carbyne chains confined
in double-walled carbon nanotubes. Our results show that carbyne's record-high
Raman scattering cross section enables anti-Stokes Raman measurements at the
single chain level. Using laser irradiation as a heating source, we exploit the
temperature dependence of the anti-Stokes/Stokes ratio for local temperature
sensing. Due to its molecular size and its large Raman cross section carbyne is
an efficient probe for local temperature monitoring, with applications ranging
from nanoelectronics to biology.
