Scanning-tunneling microscopy (STM) can image surfaces of conducting materials with atomic-scale resolution. It uses an atomically-sharp metal tip that is brought very close to the surface. When the tip and sample are connected with a voltage source, a small tunneling current flows between the tip and sample surface. This current can be measured, and the magnitude depends on the distance between the tip and the surface. As the tip is moved laterally across the surface, a feedback mechanism moves the tip up and down to maintain a constant tunneling current. Rastering the tip across the surface therefore produces a topographic map of the surface.
The STM (Scanning Tunneling Microscopy) technique is a scientific method used to image and manipulate surfaces at the atomic level. It uses a sharp probe to scan a sample surface and measures the tunneling current between the probe and the surface to create a 3D image of the surface topography.
The STM technique works by using a sharp probe made of a conducting material, such as metal, to scan a sample surface. The probe is positioned a few nanometers above the surface and a small voltage is applied between the probe and the surface. This creates a tunneling current between the two, which is then measured and used to generate a topographic image of the surface.
The STM technique has several advantages, including its ability to image surfaces at the atomic level with high resolution, its non-destructive nature, and its ability to work in a variety of environments, such as in air, vacuum, and liquid. It also allows for the manipulation of individual atoms, making it a valuable tool for nanotechnology research.
One limitation of the STM technique is that it can only be used on conducting or semi-conducting surfaces, as non-conductive surfaces will not produce a tunneling current. Additionally, the sample must be relatively flat and stable, as any movement or vibration can affect the accuracy of the images. The STM technique also has a limited depth of field and cannot provide information on the chemical composition of a sample.
The STM technique has a wide range of applications in scientific research, including in the fields of physics, chemistry, and materials science. It is used to study the properties of various surfaces, such as metals, semiconductors, and biological materials. It is also used to investigate the behavior of individual atoms and molecules, as well as to manipulate and assemble them for potential applications in nanotechnology and molecular electronics.