杏吧原创

HOLLYWOOD producers eat your hearts out. 杏吧原创s in Japan have made the first movies of ripples racing over the surfaces of crystals. They say the wave patterns could help researchers determine the structure and purity of crystal lattices simply by looking at them.

Crystal lattices consist of atoms linked by chemical bonds that can oscillate like springs. This allows vibrational waves known as phonons to pass through the structure. In an ideal crystal with no impurities or structural faults, the atomic-scale waves travel in a way that is straightforward to predict. However, impurities such as unwanted atoms inthe lattice can distort the waves and even bring them to a focus. But the mechanism behind this is complex and poorly understood.

Now Oliver Wright and his colleagues at Hokkaido University in Japan have developed a way of seeing these wave patterns in real time. They do this by bouncing ultra-short laser pulses off the surface of the crystal to measure the change in surface height that the phonons produce. The laser scans very rapidly across the surface of the crystal to build up an image of the pattern, and repeating this process produces a movie of the way the pattern changes. 鈥淭he images are very striking,鈥� says Wright.

The technique should help scientists understand how phonons become focused, which in turn may allow them to use it to measure defects in crystals鈥攁n important process in the semiconductor industry. 鈥淚t鈥檚 very neat work'鈥� says James Wolfe at the University of Illinois at Urbana-Champaign.