Most of the applications described using the RIG 150 unit involve transient experiments, measuring a concentration as a function of real time, as in the case of pulses, temperature programed experiments, in which Temperature is plotted instead of time, steps switches and isotopic exchange experiments.An application explicitly involving time, is the BET adsorption experiment showing in the figure at right.In this case a gas consisting of 30% N2 in He, flows at 60cc/min over 45 mg of a Pt/Alumina catalyst. At time zero the U-tube containing the catalyst is immersed in a Dewar containing liquid N2 and the catalyst starts adsorbing the N2 in the carrier gas, causing a decrease in the TC cell signal. After the catalyst surface is saturated with N2 the signal returns to the baseline as shown by the first peak in the figure. After a few minutes, the Dewar is removed and N2 desorbs from the sample surface and the TC cell signal increases and decreases as shown in the second peak of the figure. The volume of gas adsorbed is calculated from a calibrated signal and using the BET equation one can calculate the total surface area of the catalyst.