This was the latest breakthrough in the advancement of scanning probe microscopes -- the family of nonoptical microscopes researchers use to create striking images through raster scans of individual atoms.
The granddaddy of them all is the scanning tunneling microscope, a 1986 invention that won its creators the Nobel Prize. STMs pass an electrical probe over a substance, allowing scientists to visualize regions of high electron density and infer the position of individual atoms and molecules.
To mark the 25th anniversary of the development of STMs, an international contest -- SPMage07 -- showcasing the best STM images was founded.
Quantum Forest: This image captured in German labs by Thorsten Dziomba, shows GeSi quantum dots -- a mere 15 nanometers high and 70 nanometers in diameter.
Sapphire: As nanotechnology develops, scientists are finding innovative ways to build structures on the atomic level. Scott MacLaren, at the University of Illinois Urbana-Champaign, collaborated with Fumiya Watanabe and David Cahill to create this image of a precisely crafted crater on a sapphire substrate.
The sapphire was heated by hitting the surface with a femtosecond laser pulse that ejected atoms and left a shallow crater behind in the process. The crystal was reheated and blasted again to develop the internal step structure visible here.
E.Coli: This E. coli bacterium displays well-preserved flagella that are just 30 nanometers long.
An atomic-force microscope was used to capture the image. Unlike scanning tunneling microscopes, the tip of an AFM comes into direct contact with the surface of the sample. The force between the tip (known as "the bend") is calculated by measuring the force exerted on a tiny cantilever.
AFMs are so sensitive that they can detect forces as small as a few picoNewton (one trillionth of a Newton).
Nanowires: The leaves of several plants, including the lotus plant, show self-cleaning properties.
The so-called "lotus effect" that results means that every rain shower washes away dust particles that would otherwise reduce the plant's ability to photosynthesize and leave it feeling a bit untidy and depressed.
This 2 micron x 2 micron AFM image shows one man-made attempt to mimic the dust-busting properties of the lotus -- a carpetlike assembly of nanowires, created by a chemical vapor deposition process. When water droplets hit the superhydrophobic nanowires, they quickly roll off, taking those pesky dust particles with them.
Cyanobacteria: This image of cyanobacteria (more commonly known as blue-green algae) was taken as part of a series of experiments designed to help scientists understand how the structure of the algae's cell walls helps it move.
Simon Connell and David Adams at the university's School of Physics are applying the latest AFM techniques to biological systems like cell division, chemotaxis and symbiosis.
AFMs operate at incredibly fine levels of sensitivity, Connellsays , adding that one nanoNewton is "equivalent to the attractive force solely due to gravitation between two players on a tennis court." Ace!
Charge: An electrostatic force microscope was used to create this tapewormlike image of the charge emission from a carbon nanotube just 18 nanometers in diameter. EFMs leverage classical electrostatic forces to create images that could not be taken with STMs, Mariusz Zdrojeck says.
"EFM is a very easy method [by which] to observe electrostatic behavior of any (not only nanotubes) object in the nanoworld," says Zdrojek, who hopes that his research will make new electronic devices possible.
The bright halo is created by charges emitted from the nanotube cap, while the discharged nanotube appears dark.
Bromine Atoms: STMs are used for more than just passively viewing individual atoms. They can be used to manipulate individual atoms by picking them up (or pushing them from side to side) using the tip of the microscope, some fine calibration and a steady hand.
"STMs are the first and best tool for manipulating atoms one at a time," says Jody (Seung Yun) Yang, a University of Toronto chemist who took this STM image to demonstrate "a new method for imprinting on the molecular scale."
The result? An up-close and personal look at 12 bromine atoms, arranged in a circle through molecular self-assembly.
Yang is currently working on the development of a nanoscale printing press.
Blossoms: This 13 nanometer x 13 nanometer image shows the results of layering diindenoperylene and copper-phthalocyanines on a single gold crystal by molecular beam.
These planar organic molecules exhibit semiconductive properties. The image shows how molecules self-arrange in certain conditions -- information that is vital to scientists attempting to build semiconductors of the future.
Blood Cells: These bagel-like blood cells won second place in SPMage07, and were taken to assist research into the effects of antibiotic peptides on cell membranes.
This image shows the surface of human red blood cells after treatment with phyllomelittin, an antibiotic isolated from the skin of the monkey frog.
