Artifacts identification in apertureless near-field optical microscopy

P. G. Gucciardi, G. Bachelier, M. Allegrini, J. Ahn, M. Hong, S. Chang, W. Jhe, Seok Cheol Hong, S. H. Baek

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The aim of this paper is to provide criteria for optical artifacts recognition in reflection-mode apertureless scanning near-field optical microscopy, implementing demodulation techniques at higher harmonics. We show that optical images acquired at different harmonics, although totally uncorrelated from the topography, can be entirely due to far-field artifacts. Such observations are interpreted by developing the dipole-dipole model for the detection scheme at higher harmonics. The model, confirmed by the experiment, predicts a lack of correlation between the topography and optical images even for structures a few tens of nanometers high, due to the rectification effect introduced by the lock-in amplifier used for signal demodulation. Analytical formulas deduced for the far-field background permit to simulate and identify all the different fictitious patterns to be expected from metallic nanowires or nanoparticles of a given shape. In particular, the background dependence on the tip-oscillation amplitude is put forward as the cause of the error-signal artifacts, suggesting, at the same time, specific fine-tuning configurations for background-free imaging. Finally a careful analysis of the phase signal is carried out. In particular, our model correctly interprets the steplike dependence observed experimentally of the background phase signal versus the tip-sample distance, and suggests to look for smooth variations of the phase signal for unambiguous near-field imaging assessment.

Original languageEnglish
Article number064303
JournalJournal of Applied Physics
Volume101
Issue number6
DOIs
Publication statusPublished - 2007 Apr 8

Fingerprint

artifacts
near fields
microscopy
demodulation
harmonics
far fields
topography
dipoles
error signals
rectification
nanowires
amplifiers
tuning
nanoparticles
oscillations
scanning
causes
configurations

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)
  • Physics and Astronomy(all)

Cite this

Gucciardi, P. G., Bachelier, G., Allegrini, M., Ahn, J., Hong, M., Chang, S., ... Baek, S. H. (2007). Artifacts identification in apertureless near-field optical microscopy. Journal of Applied Physics, 101(6), [064303]. https://doi.org/10.1063/1.2696066

Artifacts identification in apertureless near-field optical microscopy. / Gucciardi, P. G.; Bachelier, G.; Allegrini, M.; Ahn, J.; Hong, M.; Chang, S.; Jhe, W.; Hong, Seok Cheol; Baek, S. H.

In: Journal of Applied Physics, Vol. 101, No. 6, 064303, 08.04.2007.

Research output: Contribution to journalArticle

Gucciardi, PG, Bachelier, G, Allegrini, M, Ahn, J, Hong, M, Chang, S, Jhe, W, Hong, SC & Baek, SH 2007, 'Artifacts identification in apertureless near-field optical microscopy', Journal of Applied Physics, vol. 101, no. 6, 064303. https://doi.org/10.1063/1.2696066
Gucciardi PG, Bachelier G, Allegrini M, Ahn J, Hong M, Chang S et al. Artifacts identification in apertureless near-field optical microscopy. Journal of Applied Physics. 2007 Apr 8;101(6). 064303. https://doi.org/10.1063/1.2696066
Gucciardi, P. G. ; Bachelier, G. ; Allegrini, M. ; Ahn, J. ; Hong, M. ; Chang, S. ; Jhe, W. ; Hong, Seok Cheol ; Baek, S. H. / Artifacts identification in apertureless near-field optical microscopy. In: Journal of Applied Physics. 2007 ; Vol. 101, No. 6.
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