Conductivity measurements of dynamically compressed matter using single-shot terahertz spectroscopy

Knowledge of the zero-frequency (DC) electrical conductivity of matter compressed to above solid density is essential for planetary models [1] and predicting dynamos [2]. Previous attempts to determine the DC conductivity of compressed matter have inferred this value fro measurements of the high frequency electrical conductivity. Here, we describe the implementation of terahertz (THz) spectroscopy into a dynamic compression experiment to measure the DC conductivity of dynamically compressed matter directly. THz spectroscopy as been used in many scientific disciples to investigate the electrical conductivity [3]. Recent development now permit the study of materials irreversibly driven to extreme conditions [4]. In our measurements, samples were compressed to megabar pressures using laser driven shock, THz measurements probed the compressed matter in a reflection geometry detection. The design of the experiment enables a convenient self-referencing and normalization, and by monitoring the change in the THz reflectivity, we infer the electrical conductivity. In addition to presenting the experimental design, we discuss the incorporation of other diagnostic into the experimental platform, such as X-ray diffraction.

[1] D Saumonet al., . High Pressure Research, 16(5-6):331–343, 2000.

[2] Ziegler et al., Geochem., Geophys. Geosys. 14, 4735 (2013).

[3] Ulbricht, R., et al., Reviews of Modern Physics, 83(2), 543–586.

[4] Ofori-Okai, et al., Review of Scientific Instruments, 89(10). 10D109