Identification of Individual Surface Atoms
The AFM can be used to image and manipulate atoms and structures on a variety of surfaces. The atom at the apex of the tip "senses" individual atoms on the underlying surface when it forms incipient chemical bonds with each atom. Because these chemical interactions subtly alter the tip's vibration frequency, they can be detected and mapped. This principle was used to distinguish between atoms of silicon, tin and lead on an alloy surface, by comparing these 'atomic fingerprints' to values obtained from large-scale density functional theory (DFT) simulations.
The trick is to first measure these forces precisely for each type of atom expected in the sample, and then to compare with forces given by DFT simulations. The team found that the tip interacted most strongly with silicon atoms, and interacted 23% and 41% less strongly with tin and lead atoms, respectively. Thus, each different type of atom can be identified in the matrix as the tip is moved across the surface.
Read more about this topic: Atomic Force Microscopy
Famous quotes containing the words individual, surface and/or atoms:
“The best that an individual can do is to concentrate on what he or she can do, in the course of a burning effort to do it better.”
—Elizabeth Bowen (1899–1973)
“All forms of beauty, like all possible phenomena, contain an element of the eternal and an element of the transitory—of the absolute and of the particular. Absolute and eternal beauty does not exist, or rather it is only an abstraction creamed from the general surface of different beauties. The particular element in each manifestation comes from the emotions: and just as we have our own particular emotions, so we have our own beauty.”
—Charles Baudelaire (1821–1867)
“Do but consider this small dust, here running in the glass,
By atoms moved.
Could you believe that this the body was
Of one that loved?
And in his mistress’ flame playing like a fly,
Turned to cinders by her eye?
Yes, and in death as life unblest,
To have’t expressed,
Even ashes of lovers find no rest.”
—Ben Jonson (1572–1637)