Versatile setup for optical spectroscopy under high pressure and low temperature

Compression rate of dynamic diamond anvil cells from room temperature to 10 K

There is an ever increasing interest in studying dynamic-pressure dependent phenomena utilizing dynamic Diamond Anvil Cells (dDACs), devices capable of a highly controlled rate of compression. Here, we characterize and compare the compression rate of dDACs in which the compression is actuated via three different methods: (1) stepper motor (S-dDAC), (2) gas membrane (M-dDAC), and (3) piezoactuator (P-dDAC). The compression rates of these different types of dDAC were determined solely on millisecond time-resolved R1-line fluorescence of a ruby sphere located within the sample chamber. Furthermore, these different dynamic compression-techniques have been described and characterized over a broad temperature and pressure range from 10 to 300 K and 0-50 GPa. At room temperature, piezoactuation (P-dDAC) has a clear advantage in controlled extremely fast compression, having recorded a compression rate of ∼7 TPa/s, which is also found to be primarily influenced by the charging time of the piezostack. At 40-250 K, gas membranes (M-dDAC) have also been found to generate rapid compression of ∼0.5-3 TPa/s and are readily interfaced with moderate cryogenic and ultrahigh vacuum conditions. Approaching more extreme cryogenic conditions (<10 K), a stepper motor driven lever arm (S-dDAC) offers a solution for high-precision moderate compression rates in a regime where P-dDACs and M-dDACs can become difficult to incorporate. The results of this paper demonstrate the applicability of different dynamic compression techniques, and when applied, they can offer us new insights into matter's response to strain, which is highly relevant to physics, geoscience, and chemistry.

Infrared spectroscopic monitoring of solid-state processes

We put a spotlight on IR spectroscopic investigations in materials science by providing a critical insight into the state of the art, covering both fundamental aspects, examples of its utilisation, and current challenges and perspectives focusing on the solid state.

Adapting a continuous flow cryostat and a plate DAC to do high pressure Raman experiments at low temperatures

We present a method for modifying a continuous flow cryostat and a steel plate DAC (Diamond Anvil Cell) to perform high pressure micro-Raman experiments at low temperatures. Despite using a steel DAC with a lower specific heat capacity (∼335 J/kg K), this setup can routinely perform high pressure (∼10 GPa) measurements at temperatures as low as 26 K. This adaptation is appropriate for varying the temperature of the sample while keeping it at a constant pressure. We determined that the temperature variation across the sample chamber is about 1 K using both direct temperature measurements and finite element analysis of the heat transport across the DAC. We present Raman spectroscopy results on elemental selenium at high pressures and low temperatures using our modified setup.