Nano-ruler sets some very small marks

September 22, 2009

The National Institute of Standards and Technology has issued a new ruler, and even for an organization that routinely deals in superlatives, it sets some records. Designed to be the most accurate commercially available "meter stick" for the nano world, the new measuring tool -- a calibration standard for X-ray diffraction -- boasts uncertainties below a femtometer. That's 0.000 000 000 000 001 meter, or roughly the size of a neutron.

The new ruler is in the form of a thin, multilayer 25 millimeters square (just under an inch). Each one is individually measured and certified by NIST for the spacing and angles of the crystal planes of silicon atoms in the base crystal.

X-ray diffraction works by sending X-rays through a crystal—which could be anything from a wafer used to make microchips to a crystallized sample of an unknown protein—and observing the patterns made by the X-rays as they diffract from electrons in the crystal. The spacing, angles and intensity of the pattern's lines tell a trained crystallographer the relative positions of the atoms in the crystal, as well as something about the quality of the crystal, the nature of the chemical bonds and more. It is one of the workhorse techniques of materials science and engineering. The precision version, high-resolution X-ray diffraction, can be used to determine the thickness, crystal structure, embedded strain and orientation of thin films used in advanced semiconductor devices and nanotechnologies.

Formally NIST Standard Reference Material (SRM) 2000, "Calibration Standard for High-Resolution ," the new ruler gives crystallographers an extremely well-known crystal sample for calibrating their precision instruments. It was made possible by the development of a unique parallel beam diffractometer at NIST that makes measurements traceable to international measurement standards and is believed to be the most accurate angle measuring device of its kind in the world. The NIST instrument can measure angles with an accuracy better than an arc second, 1/3600 of a degree. "Our accuracy is at about the angle made by the diameter of a quarter—if you're looking at it from two miles away," explains NIST materials scientist Donald Windover, "The precision is better, about the size of Washington's nose."

Because the crystal lattice values for SRM 2000—spacing, tilt, orientation—are traceable to SI units, the new material provides an absolute reference for high-precision calibrations. Details are available at https://www-s.nist.gov/srmors/view_detail.cfm?srm=2000.

Source: National Institute of Standards and Technology (news : web)

Explore further: Crystal structure library gets a 'data lift'

Related Stories

Crystal structure library gets a 'data lift'

March 6, 2006

Much of science these days depends on "black (or beige) boxes," scientific instruments that invisibly analyze data and then, voilá, identify the chemistry and/or structure of a sample. While scientists and engineers may ...

Stress Management: X-Rays Reveal Si Thin-Film Defects

July 6, 2006

Pile-ups, bad on the freeway, also are a hazard for the makers of high-performance strained-silicon semiconductor devices. A sensitive X-ray diffraction imaging technique developed by researchers at the National Institute ...

NIST releases new standard for semiconductor industry

October 12, 2006

A wide range of optical electronic devices, from laser disk players to traffic lights, may be improved in the future thanks to a small piece of semiconductor, about the size of a button, coated with aluminum, gallium, and ...

Recommended for you

New nanomaterial maintains conductivity in 3-D

September 4, 2015

An international team of scientists has developed what may be the first one-step process for making seamless carbon-based nanomaterials that possess superior thermal, electrical and mechanical properties in three dimensions.

Graphene made superconductive by doping with lithium atoms

September 2, 2015

(Phys.org)—A team of researchers from Germany and Canada has found a way to make graphene superconductive—by doping it with lithium atoms. In their paper they have uploaded to the preprint server arXiv, the team describes ...

Making nanowires from protein and DNA

September 3, 2015

The ability to custom design biological materials such as protein and DNA opens up technological possibilities that were unimaginable just a few decades ago. For example, synthetic structures made of DNA could one day be ...

For 2-D boron, it's all about that base

September 2, 2015

Rice University scientists have theoretically determined that the properties of atom-thick sheets of boron depend on where those atoms land.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.