On-site in situ high-pressure ultrafast pump-probe spectroscopy instrument

We conceive and construct an on-site in situ high-pressure time-resolved ultrafast optical spectroscopy instrument that facilitates ultrafast pump-probe dynamics measurements under high pressure conditions. We integrate an ultrafast pump-probe spectroscopy system with a diamond anvil cell (DAC) system. Significantly, both the DAC and the sample are fixed within the light path without motion and rotation throughout the whole ultrafast spectroscopy experiment, including tuning and calibrating the pressure. This instrument thus avoids introducing artifacts due to sample motion or rotation, enabling precision high-pressure ultrafast pump-probe dynamics investigations. As a demonstrating example, we compare the effect of on-site in situ conditions with off-site in situ conditions on the ultrafast dynamics of Sr₂IrO₄ under 0-44.5 GPa high pressure. Our data and analysis show that conventional possible artifacts are greatly reduced by using the on-site in situ layout. Our work helps the high-pressure ultrafast science investigation develop into a promising new area, which enables the exploration of nonequilibrium excited quantum states in the high-pressure regime.