Scanning Interferometric Apertureless Microscopy at 10 Angstrom Resoultion
Near-field scanning microscopy at microwave frequencies (1) and its extension to the visible region (NSOM)(2, 3) at around 50 nm resolution has attracted much attention (4–7). Recently, a Scanning Interferometric Apertureless Microscope (SIAM) was introduced (8, 9, 14) where the scattered electric field variation due to a vibrating and scanning probe tip in close proximity to a sample surface is measured by encoding it as a modulation in the phase of one arm of an interferometer. Here, we review the SIAM technique and present images of various samples at a resolution of 1 nm - almost two orders of magnitude superior to other NSQM’s. A basic theory based on coupled dipoles is put forward and compared with experiments. It shows that the contrast mechanisms are fundamentally different to those in regular near-field optical microscopes due to a unique dipole-dipole mechanism. Furthermore, the theory predicts the ability to measure complex susceptibility down to the atomic level.
KeywordsOptical Image Couple Dipole Scattered Field Force Gradient Interferometric Phase
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