Reply to "Comment on 'Scanning-probe Raman spectroscopy with single-molecule sensitivity' "
By: C. C. Neacsu, J. Dreyer, N. Behr, and M. B. Raschke
Physical Review B 75, 236402 (2007)
In the Comment by Domke and Pettinger [Phys. Rev. B 75, 236401 (2007)] on our study on 'Scanning-probe Raman spectroscopy with single-molecule sensitivity' [C. C. Neacsu et al. Phys. Rev. B 73, 193406 (2006)] the authors raise concerns whether our tip-enhanced Raman response is due to carbon clusters as molecular decomposition products of the malachite green molecules used. Their arguments are based on the different spectral characteristics we observe between the tip-enhanced and far-field Raman response. Here, we show the results of systematic control experiments to support the conclusions drawn by Neacsu et al. that all spectral features can be related to malachite green molecules. Comparing Raman spectra for different degrees of near-field enhancement, the absence of spectral changes during bleaching, examining a broad spectral range, and the explicit comparison with Raman signals from carbon impurities validates our original assignment, including the single-molecule response.