These tips can have radii of curvature as small as 5 nm but are often larger, and have pyramid half cone angles of about 35° (refs. Common, commercially available AFM probes consist of microfabricated silicon or silicon nitride cantilevers with integrated pyramidal tips. 1– 12 and whether the sample consists of isolated molecules or packed molecular arrays ( 6, 13). The level of information obtained from AFM images, however, depends critically on the size, shape, and terminal functionality of the probe tips used for imaging (refs. These molecular-scale CVD nanotube probes have been used to image isolated IgG and GroES proteins at high-resolution.Ītomic force microscopy (AFM) has become an important technique in biology and chemistry due to its unique ability to image and characterize structures in liquid, ambient, and vacuum environments ( 1– 4). Moreover, the nanotube tip radii determined from the nanoparticle images are consistent with those determined directly by transmission electron microscopy imaging of the nanotube ends. Analysis of images recorded on gold nanoparticle standards shows that these multi- and single-walled carbon nanotube tips have radii of curvature of 3–6 and 2–4 nm, respectively. Force-displacement measurements made on the tips show that they buckle elastically and have very small (≤ 100 pN) nonspecific adhesion on mica surfaces in air. Scanning electron microscopy and transmission electron microscopy measurements demonstrate that multiwalled nanotube and single-walled nanotube tips can be grown by predictable variations in the CVD growth conditions. This communication describes methods for the direct growth of carbon nanotube tips by chemical vapor deposition (CVD) using ethylene and iron catalysts deposited on commercial silicon-cantilever-tip assemblies.
Carbon nanotubes are potentially ideal atomic force microscopy probes because they can have diameters as small as one nanometer, have robust mechanical properties, and can be specifically functionalized with chemical and biological probes at the tip ends.
0 kommentar(er)
