ANN ARBOR---Researchers at the University of Michigan's Center for Ultrafast Optical Sciences have built the first table-top laser capable of generating a coherent beam of X-rays.
The work could give chemists a close-up view of the dynamics of atoms during reactions with other atoms, and open a real-time window for biologists onto microscopic events at the cellular level. It appears in the May 29 issue of the journal Science, along with an accompanying news article.
By shooting a rapidly pulsing laser through a hollow glass tube filled with gas and controlling the pressure of that gas, the team---including Andy Rundquist, Charles Durfee, and electrical engineering professors Henry Kapteyn and Margaret Murnane and colleagues---were able to generate a focused beam of X-rays that could be incorporated into a device for atomic-scale imaging.
Although it has long been possible to generate X-rays with lasers, this is the first time scientists have been able to dramatically increase their efficiency to make them useful for applications, such as imaging, Murnane said. Moreover, whereas traditional lasers emit visible and near-infrared light (with wavelengths in the 500-1000 nanometer range), those from the U-M device are about 20nm, with the possibility of being as short as 2nm. The shorter the wavelength, the higher the spatial resolution of the beam.
Another benefit of this new device is that the X-ray pulse duration is extremely short, enabling high temporal resolution imaging as well. In other words, the X-rays can be used as the world's fastest strobe light, making anything moving slower appear to be frozen in time.
The U-M device consists of a hollow glass tube filled with gas, sandwiched
between a laser source and a detector. When the intense light passes through
the gas, electrons---the negatively charged particles swarming around
atoms---are pulled away from the atoms, then slammed back when the field
reverses direction. The electron t
Contact: Adam Marcus
University of Michigan