Laser-heated diamond anvil cell at the advanced light source beamline 12.2.2

The laser-heating system for the diamond anvil cell at endstation 2 of beamline 12.2.2 of the Advanced Light Source in Berkeley, CA, has been constructed and is available for in situ high-pressure high-temperature X-ray experiments. The endstation couples a highbrilliance synchrotron X-ray source with an industrial strength laser to heat and probe samples at high pressure in the diamond anvil cell. The system incorporates an 50W Nd : YLF (cw) laser operated in TEM01* mode. Double-sided heating is achieved by splitting the laser beam into two paths that are directed through the opposing diamond anvils. X-ray transparent mirrors steer the laser beams coaxial with the X-ray beam from the superconducting bending magnet (energy range 6-35 KeV) and direct the emitted light from the heated sample into two separate spectrometers for temperature measurement by spectroradiometry. Objective lenses focus the laser beam to a size of 25 Am diameter (FWHM) in the sample region. An X-ray spot size of 10 Am diameter (FWHM) has been achieved with the installation of a pair of focusing Kirkpatrick-Baez mirrors. A unique aperture configuration has produced an X-ray beam profile that has very low intensity in the tails. The main thrust of the program is aimed at producing in situ high-pressure high-temperature X-ray diffraction data, but other modes of operation, such as X-ray imaging have been accomplished. Technical details of the experimental setup will be presented along with initial results. (C) 2007 Elsevier B.V. All rights reserved.