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Biological techniques and instruments; Biomembranes; Molecular biophysics; Scanning tunnelling microscopy; Natural and artificial biomembranes [A8720E]; Biomolecular structure, configuration, conformation, and active sites [A8715B]; Biophysical instrumentation and techniques [A8780]
Abstract:
Scanning tunneling microscopy images of uncoated purple membrane are easily obtained at tunneling currents lower than 1 pA and tunneling voltages above approximately 7 V. However, the images sometimes show positive, sometimes negative contrast. This effect appears to depend only on the shape of the tunneling tip. A simple model, assuming a constant voltage drop across the purple membrane, is proposed which can explain this observation. (13 References).
