scanning tunneling microscope

Examples of scanning tunneling microscope in the following topics:

• Scanned-Probe Microscopy

  • Scanned-probe microscopy uses a fine probe rather than a light-beam or electrons to scan the surface of a specimen and produce a 3D image.
  • Scanned-probe microscopy (SPM) produces highly magnified and three-dimensional-shaped images of specimens in real time.
  • Scanning tunneling microscopy (STM) measures a weak electrical current flowing between tip and sample as they are held apart.
  • Near-field scanning optical microscopy (NSOM) scans a very small light source very close to the sample.
  • Describe the different types of scanning probe techniques and their advantages over other types of microscopy

• Quantum-Mechanical View of Atoms

  • Atoms in solid states (or, to be precise, their electron clouds) can be observed individually using special instruments such as the scanning tunneling microscope.

• Specialty Microscopes and Contrast

  • There are many types of microscopes: optical microscopes, transmission electron microscopes, scanning electron microscopes and scanning probe microscopes.
  • One way to group microscopes is based on how the image is generated through the microscope.
  • Microscopes can also be classified based on whether they analyze the sample by scanning a point at a time (scanning electron microscopes), or by analyzing the entire sample at once (transmission electron microscopes).
  • Scanning Electron Microscopes: Referred to as SEM, these microscopes look at the surface of objects by scanning them with a fine electron beam .
  • Atomic Force Microscopy: The AFM is a scanning probe type of microscopy with very high resolution and is one of the foremost tools for imaging at the nanoscale.

• Blood-Brain Barrier

  • These harmful bacteria seem to breach the BBB by physically tunneling through the blood vessel walls.
  • It was not until the introduction of the scanning electron microscope that the actual membrane could be observed and proven to exist.
  • The diffusion of microscopic particles (e.g., bacteria) large molecules and hydrophilic molecules into the CSF is restricted, while the diffusion of small hydrophobic molecules (O2, CO2, hormones) is permitted.
  • These harmful bacteria seem to breach the BBB by physically tunneling through the blood vessel walls.

• Electron Microscopes

  • An electron microscope is a microscope that uses an electron beam to create an image of the target.
  • It has much higher magnification or resolving power than a normal light microscope.
  • Let's first review how a regular optical microscope works .
  • Electron microscopes are very useful as they are able to magnify objects to a much higher resolution.
  • Diagram of the basic components of an optical microscope and an electron microscope.

• Microscopy

  • A microscope is an instrument that magnifies an object.
  • Most student microscopes are classified as light microscopes .
  • In contrast to light microscopes, electron microscopes use a beam of electrons instead of a beam of light.
  • In a scanning electron microscope, a beam of electrons moves back and forth across a cell's surface, creating details of cell surface characteristics.
  • As you might imagine, electron microscopes are significantly more bulky and expensive than light microscopes.

• Enhancement of Microscopy

  • Microscopes are used to view objects that cannot be seen with the naked eye.
  • You have probably used an optical microscope in a high school science class.
  • Two kinds of electron microscopes are:
  • Transmission electron microscope (TEM): The TEM sends an electron beam through a thin slice of a specimen.
  • Scanning electron microscope (SEM): The SEM shows details on the surface of a specimen and produces a three-dimensional view by scanning the specimen. shows an SEM image of pollen.

• Electron Microscopy

  • There are two types of electron microscopes .
  • The more traditional form is the transmission electron microscope (TEM).
  • The second and most contemporary form is the scanning electron microscope (SEM).

• Confocal Microscopy

  • Confocal microscopy is a non-invasive fluorescent imaging technique that uses lasers of various colors to scan across a specimen with the aid of scanning mirrors.
  • The scanning process uses a device that is under computer control.
  • Development of modern confocal microscopes has been accelerated by new advances in computer and storage technology, laser systems, detectors, interference filters, and fluorophores for highly specific targets.

• Cells as the Basic Unit of Life

  • (a) Nasal sinus cells (viewed with a light microscope), (b) onion cells (viewed with a light microscope), and (c) Vibrio tasmaniensis bacterial cells (seen through a scanning electron microscope) are from very different organisms, yet all share certain characteristics of basic cell structure.