A NEW EXPERIMENTAL-TECHNIQUE TO STUDY SUPERCRITICAL-FLUID PHASES AT CONDITIONS UP TO 550-DEGREES-C AND 5KBAR

A new experimental technique is presented that combines a high pressur e, high temperature vessel with an ultra-high vacuum chamber (10(-10) mbar). A quadrupole mass-spectrometer is used in combination with an o pen crossbeam ion source for measurements of a molecular beam of super critical fluid ''leaked'' through a custom-built high-temperature need le valve. In general, the technique allows for the study of the compos ition of supercritical fluids that have or have not interacted with so lid phases such as minerals; glass, or metals. Experimental studies ca n be carried out in a pressure-temperature range oi up to 5 kbar and 5 50 degrees C. Three spectra are presented that show the results of mea surements of pure CO2-H2O fluids and of a mixed CO2-H2O fluid which wa s in contact with silica gel.