Biomolecules and nanostructures
The Optical Sciences group studies the interaction of light and matter at the nanoscale.
We do this by exploring ways to shape light and its environment. It's what we call
active and passive control. Our current focus is on the interaction of light with
biomolecules and nanostructures. We are part of Twente
University's Department of Science and Technology and member of the
POLARIZATION CONTRAST IN PHOTON SCANNING-TUNNELING-MICROSCOPY COMBINED WITH ATOMIC-FORCE MICROSCOPY
PROPSTRA K, VANHULST NF
JOURNAL OF MICROSCOPY-OXFORD
vol 180: p165-p173 part 2 NOV 1995
Photon scanning tunnelling microscopy combined with atomic force microscopy allows simultaneous acquisition and direct comparison of optical and topographical images, both with a lateral resolution of about 30 nm, far beyond the optical diffraction limit. The probe consists of a modified microfabricated silicon nitride tip mounted on a cantilever, commercially available for atomic force microscopy. The lateral resolution is further improved using 'supertips', by depositing a small needle on the silicon nitride tip. The combined microscopic technique is applied to thin films of indium tin oxide because of the small grain size and high surface flatness, providing high-resolution optical contrast and limited far-field scattering contribution. Polarization contrast is shown in experiments both changing the polarization of the incident and detected light. Approach curves, both measuring the optical signal and force interaction, show a difference in the optical coupling between p- and s-polarized incident light, p-Polarized light always provides optical contrast more correlated to topography than s-polarized light, both for incident and detected light, in agreement with theoretical models.