Experimental technique for quantitative IR studies of highly absorbing substances at high temperatures and pressures

A new high-temperature/high-pressure IR cell with a changeable pathlength i s described. The pathlength can be varied immediately during a run at high pressure and temperature with a driving mechanism attached to the body of t he cell. This arrangement presents the possibility of avoiding most of the common and specific errors connected with intensity measurements in the dif ficult case of highly absorbing substances. The cell can be used up to 780 K at a pressure of 100 MPa. The algorithms of data processing and examples of representative spectra of water are also discussed.