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Near‐field optical microscopy of localized excitations on rough surfaces: influence of a probe
Author(s) -
Bozhevolnyi S. I.
Publication year - 1999
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.1999.00501.x
Subject(s) - polarizability , dipole , perturbation (astronomy) , electric field , physics , microscopy , molecular physics , optics , intensity (physics) , atomic physics , chemistry , condensed matter physics , quantum mechanics , molecule
Starting from the general principles of near‐field optical microscopy, I consider the influence of a probe when being used to image localized dipolar excitations and suggest a way of evaluating the perturbation thus introduced. Using the rigorous microscopic (electric) point–dipole description, I calculate the self‐consistent field intensity at the site of a probe dipole scanning over resonantly interacting object dipoles and show that the intensity distribution deviates from that existing in the absence of a probe. I demonstrate that this difference increases with an increase in the polarizability of the probe dipole, resulting eventually in a completely different intensity distribution. The calculations also show that the perturbation of the intensity distribution due to the presence of a probe decreases with an increase in the probe–sample distance. In order to evaluate the degree of perturbation, I suggest comparing the images obtained at different probe–sample distances. Finally, I formulate a simple rule of thumb that allows one to roughly estimate the probe–sample coupling when imaging localized excitations.