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Silicon (111) surface terminated with hydrogen by anmonium-fluoridetreatment was observed with an ultrahigh-vacuum atomic force microscope(UHV-AFM). Monoatomic steps, triangular etch pits and contamination islandswere imaged. Atomically resolved images were also obtained and the periodicityin these images is in good agreement with the Si(111)-H-1x1(monohydride)structure. The corrugation amplitude is 0.10-0.12nm which is much largerthan any STM result. This value is in fairly good agreement with the valueexpected in the contact hard sphere model.
Atomic force microscopy(AFM) has been used to investigate Langmuir-Blodgettfilms of the photosynthetic protein membrane obtained from photosyntheticbacteria Rhodopseudomonas viridis deposited on glass substrates. Membranestructures with small domains composed of hexagonally packed photoreactionunits(PRUs) were imaged. The average spacing between PRUs in the AFM imageis approximately 12nm, which is in good agreement with transmission electronmicroscopy data. Observation on the 100nm scale reveals that the filmsconsist of membrane fragments of diameter ranging from 0.1 to 1 micrometer.The recently developed force modulation technique was also used to imagethe local mechanical properties of the samples. There was a large differencebetween the images of the protein and the substrate.
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