A COOL WAY TO MELT

摘要

An unusual manner of melting has been observed directly with germanium crystals: When excited with an intense pulse of light from a laser, the crystals turn into liquid without the solid first becoming hot. They then revert to the ordered state. Called nonthermal melting because the phase change does not involve the classical equilibria between solid and liquid states, the phenomenon has been observed at atomic resolution by ultra-fast, time-resolved X-ray diffraction.