High temperature high pressure (HTHP) cell in sum frequency generation (SFG) spectroscopy for oil/brine interface analysis with salinity control system

A pressure cell includes a metal pressure chamber, a heating stage, disposed in the interior of the metal pressure chamber, that heats the liquid sample, a chamber pump, connected to the interior of the metal pressure chamber, that pressurizes the interior of the metal pressure chamber, a salinity control system including a membrane coupled to the sample inlet, where the membrane is configured to reduce a salinity level of the liquid sample, and a controller that controls the chamber pump, the salinity control system, and the heating stage to control a pressure of the interior of the metal pressure chamber, a salinity level of the liquid sample, and a temperature of the liquid sample, respectively. The metal pressure chamber includes a liquid sample holder, a removable lid, a window in the removable lid, a sample inlet, and a sample outlet.