A New Type of Atomic Microscope Getting Closer

Researchers at the Surface Science Laboratory at Universidad Autonoma de Madrid have created an ultrasmooth mirror that could be used to create a revolutionary new atomic microscope within the next several years. The new atomic microscope has the potential to provide the same resolution as existing electron microscopes but without many of the problems which have plagued them for years.




 

 Part of the apparatus used by the Spanish team (Credit: Ciudad Universitaria de Cantoblanco)
Part of the apparatus used
by the Spanish team
(Credit: Ciudad Universitaria de Cantoblanco)

The mirror surface resembles a curved wafer. Composed of a thin silicon crystal covered with a very fine layer of lead, the mirror reflects up to 67% of helium atoms bounced at its surface rather than the 1% reflected by previous efforts to create an atomic mirror. The silicon crystal is approximately 50 microns thick with a layer of lead; that’s a mere 1-2 nanometers thick. The lead is applied at 114 degrees Kelvin (-159 degrees Celsius or approximately -255 degrees Fahrenheit). The cold temperature allows the surface to form smoothly thanks to quantum stabilizing effects. The surface retains its smoothness as temperatures are brought back to a workable laboratory range.

A mirror capable of reflecting a beam of helium atoms would finally make an atom microscope possible. An atom microscope has several benefits over the electron microscopes in current use. The high speed electrons used in the electron microscope damage or destroy delicate biological samples, making it difficult to get accurate results and impossible to repeat tests. Scientists believe an atom microscope could provide the same level of resolution without any damage to samples.

In addition, electron microscopes only work on samples with conductive properties and their beams of electrons penetrate into samples, thus failing to image the surface layer of samples. An atom microscope would work on different types of conducive material, semiconductors, and insulating materials equally well. It would map the surface of samples, providing an alternate view and additional information about samples not available through electron microscopes.

 Helium Atom Scattering (HAS) scheme (Credit: Ciudad Universitaria de Cantoblanco)
Helium Atom Scattering (HAS) scheme
(Credit: Ciudad Universitaria de Cantoblanco)

The next step is creating a mirror with a curved surface that retains the same smoothness and reflexivity. The eventual goal is to couple a curved mirror with a beam of helium atoms 20 nanometers across, but Surface Science Laboratory director Rodolfo Miranda hopes to create a curved mirror capable of focusing a 100 nanometer beam by next summer.

Several groups of researchers are working on designs for atom microscopes using the Surface Science Laboratory’s quantum stabilized atom mirror. It is unclear at this time what the final design of any microscope will encompass other than its use of a curved version of the mirror.

TFOT has reported on other microscope technology including an ultra compact optical microscope small enough to fit on a finger tip, attempts to create a cell phone microscope, and a new scanning tunneling microscope capable of imaging individual atoms on a surface.

The Thermal Energy Atomic and Molecular Scattering group at the Surface Science Laboratory describes the scattering process in detail here. Information about the article in the Advanced Materials journal including a link to the article itself (requiring an additional fee) can be found here.