A Technique for the Raman Spectroscopy of High Pressure Phases Recovered at Low Temperatures. The Low Frequency Raman Spectrum of Ammonium Fluoride II

A technique is described for recording the Raman spectra of polycrystalline high pressure phases. The phase is made under pressure with a short piece of copper channel embedded in it and cooled to liquid nitrogen temperature under pressure. The sample is removed from the pressure vessel and the faces of the sample in the channel scraped flat and perhaps polished. The channel is mounted on the cold finger of a low temperature cell and the spectrum recorded at ∼100 K. Any powdered sample of a reasonably ductile material can of course be pressed into the channel and a clear block obtained. The Raman spectra of ammonium fluoride I and II obtained in this way are reported and briefly discussed.