A Synchrotron Microscope for pressure-dependent Far-InfraredMeasurements in Diamond Anvil Cells under vacuum at BESSY

摘要

Infrared spectroscopy is one of the most powerful tools in identifying minerals and provides manydifferent applications for examining the local structure of materials and detecting even very smallamounts of impurities. Combined with experiments in diamond-anvil-cells (DAC) it provides importantinsights in pressure-induced structural changes such as phase transitions, cation order and disorderetc. Mid-Infrared-measurements (wavelength 10 – 20 !inn) in DAC can easily be performed with anaperture diameter of about 100 pm or smaller using a conventional IR source (e.g. Koch-Muller et al.2005), which allows reaching pressures up to 50 GPa and even more. Problems arise in the Far-Infrared (FIR) region as with increasing wavelength of the light (20 – 200 pm) the insitu DACexperiments would require an aperture of at least 1 mm to overcome the loss of light due to diffraction.That would limit the applied pressure to about 1 GPa. However, when investigating pressure-inducedstructural changes the FIR region provides important information as in this region the vibrations, inwhich the metal cations are involved, occur and it would be desirable to investigate the FIR region alsoat high pressures.