Electron Microscope Noise Barrier

Researchers working with advancing electron microscopy have encountered a noise source from thermal vibrations in the atomic structure of materials that generates an interfering magnetic field for the incident electrons, possibly introducing a physical limit to the resolution possible with the technology.

Atomic Bonds Visualized

Scientists have developed a variant of an imaging method called atomic force microscopy (AFM) to take single-molecule images so detailed that the types of atomic bonds and local distortions in atomic arrangement can be seen.

New Microscopy Method Provides Increased Resolution

Scientists at the Howard Hughes Medical Institute's Janelia Farm Research Campus have developed a new method that produces the best three-dimensional resolution ever with an optical microscope.

Beginning with the super-high resolution photoactivated localization microscopy (PALM), researchers added an interferometry method to create what they call interferometric photoactivated localization microscopy (iPALM). iPALM provides resolution down to about 10 to 20 nanometers, or roughly ten times the size of an average protein molecule. The new method also allows a three-dimensional measurement of image depth, an attribute difficult to obtain with optical microscopes.

The science of interferometry uses a light beam reflected off a surface and then compared with its original beam. As it is reflected, the light undergoes a small shift in wavelength that can be detected and measured for incredibly small differences in depth and distance, such as on the surface of a computer chip. PALM extends the resolution for conventional optical microscopes, which are inherently limited by the wavelength of visible light, and iPALM can theoretically achieve resolutions on the subatomic scale.

iPALM uses a very modest amount of light, which is critical for some biological samples that could either be damaged by strong light or distorted by the need to use reflective dyes for optical measurements.

These results were published in the February 2nd issue of the Proceedings of the National Academy of Sciences.

Source: ScienceDaily