First Molecular Movie

Light Moving Through Condensed Matter: the First Molecular Movie

Contact: Lynn Yarris, lcyarris@lbl.gov

While it won't compete at the box office with Titanic, a movie made by an international collaboration of scientists working at Berkeley Lab's Advanced Light Source (ALS) stands alone for originality: it's the first ever based on recorded observations of light moving through matter at the molecular level. Unlike a box office blockbuster, this movie carries ramifications well beyond summer entertainment, as it illuminates a possibility for using light to alter material properties. A computer graphic movie shows a wave of terahertz radiation propagating through a crystal of lithium tantalate, against an x ray diffraction pattern of the material. (Go here for the mpg movie file.) "If you want to understand the propagation of light through condensed matter at a microscopic level, especially in some of the complex materials that are of interest for modern optoelectronic applications, you need to make a molecular movie of how the atoms and electrons wiggle in the light field," says Andrea Cavalleri, a physicist now at Oxford University who was a member of Berkeley Lab's Materials Sciences Division at the time of the experiments. "We were able to do this by combining ultrafast pulses of laser light with the electron beam at the ALS to create a camera with an extremely quick shutter speed."