Scanning probe microscopy in material science and biology
With this review we want to give an overview of the activity of scanning probe microscopy at ISM-CNR, Italy. The first Italian STM was built at our Institute in the mid 80s, and since then we had strong instrumentation and software development of STM, AFM and SNOM. Some of the most important experiments in material science and biology performed by our group through the years with these SPM techniques are presented. Finally, infrared applications by coupling a SNOM with a Free Electron Laser at Nashville, USA, are also presented.
Several instruments are described starting from the first air operating STM, that could get atomic resolution on cleaved graphite and the helical structure of DNA, a Scanning Probe Microscope with interchangeable head for STM, AFM and SNOM in order to visualize the same sample with different probes, a UHV STM, with a variable temperature sample stage as well as AFM working in liquid, and a SNOM coupled with the infrared light from a Free Electron Laser. A custom-built SNOM head attached to an inverted optical microscope is also described.
Early observations of metal on semiconductor reconstructions by STM showed clear atomic-scale features, although interpretation was sometimes controversial. STM images of Au(111) revealed the first observations of close-packed metal atoms, followed by atomic scale observation of the uniaxial reconstruction of this surface.
UHV STM has allowed detection of the dynamical behaviour of the surface atoms on the α-Sn/Ge(111) surface and determination of atomic surface structure by combining STM experiments with theoretical modelling. Another interesting result was the local structure of silicon nanoribbons deposited on the Ag(110) substrate.
AFM has been used to resolve the structure of neuronal networks after exposure to glutamate, morphological alteration occurring in Raji cells after exposure to 50 Hz, 2 mT magnetic fields, the uptake of heavy metals in pancreatic INS-1 cells, the morphology of normal erythrocytes and that of cells treated with different concentration of nifedipine, and the analysis of the metallic component of meteorites. With SNOM we could get images of a silicon sample after boron implantation and annealing, fluorescence images on LiF after exposure to x-rays, scan of the surface over large areas, and infrared nanospectroscopy.
Images: The above left figure shows (a) a partially covered surface which exhibits isolated Si nanoribbons 0.8 nm wide aligned along [-110] direction on Ag(110) surface and (b) a fully covered surface. The above right figure shows the overall morphology of red blood cells for a control sample (a, 10 x 10 μm2) and after treatment with: 0.2 mM nifedipine for 30 s (b, 22 x 22 μm2); 0.2 mM for 1 h (c, 15 x 15 μm2) and 1mM for 1 h (d).
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Scanning probe microscopy in material science and biology
A Cricenti et al 2011 J. Phys. D. Appl. Phys. 44 464008
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About the author
Dr Antonio Cricenti received his PhD degree in Physics from the University of Rome 'La Sapienza'. He is Research Director at CNR-ISM, Rome, Italy and Adjunct Professor at Department of Physics, Vanderbilt University, Nashville, TN, USA. His main interest has been in Scanning Probe Microscopy development and application in material science and biology. He is currently responsible for the Scanning Probe Microscopy laboratory at CNR-ISM.
Group website: http://www.ism.cnr.it/english/linee/MD.P06.006.php
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