KMgF3:Eu2+ as a new fluorescence-based pressure sensor for diamond anvil cell experiments

We present an optical pressure sensor KMgF3:Eu2+ suitable for experiments in diamond anvil cell (DAC), which we have calibrated against the ruby reference sensor at pressures ranging from atmospheric up to 30 GPa (300 kbar), at room temperature. The emission spectra of KMgF3:Eu2+ consist of one prominent emission line related to the 6P7/2 → 8S7/2 electronic transition (zero phonon line) accompanied by weak phonon sidebands. The energy of emission at atmospheric pressure was determined to be 27846 ± 7 cm−1. The edge of the excitation spectrum lies at wavelength around 325 nm (30800 cm−1) making it suitable to excite with He-Cd laser (325 nm). The sensor exhibits linear pressure shift of rate equal to −0.815 ± 0.007 cm−1/kbar at pressures up to 300 kbar. The pressure shift of the emission is totally reversible and the pressure sensor is suitable for multi cycle pressure experiments. The sensor's exceptional feature is that excitation and emission spectra lie in near UV, which makes it very convenient to use in high pressure optical measurements in visible and IR region with no interference from the sensor's luminescence.