Photodynamics of individual fluorescence molecules has been studied using an aperture-type near-field scanning optical microscope with two channel fluorescence polarisation detection and tuning fork shear-force feedback. The position of maximum fluorescence from individual molecules could be localised with an accuracy of 1 nm. Dynamic processes such as translational and rotational diffusion were observed for molecules adsorbed to a glass surface or embedded in a polymer host. The in-plane molecular dipole orientation could be determined by monitoring the relative contribution of the fluorescence signal in the two perpendicular polarised direct:ions. Rotational dynamics was investigated on 10 ms-1000 s timescale. Shear-force phase feedback was used to obtain topographic imaging of DNA fragments, with a lateral and vertical resolution comparable to scanning force microscopy. A DNA height of 1.4 nm has been measured, an indication of the non-disturbing character of the shear force mechanism.
- Optical microscopy
- Shear force microscopy
Garcia Parajo, M. F., Veerman, J. A., Ruiter, A. G. T., & van Hulst, N. F. (1998). Near-field optical and shear-force microscopy of single fluorophores and DNA molecules. Ultramicroscopy, 1998(71), 311-319. https://doi.org/10.1016/S0304-3991(97)00086-7