Apparatus for the continuous investigation of chemical reactions by infrared (IR) absorption

An apparatus is disclosed comprising an IR spectrophotometer having a throughflow cell through which flows a continuous sample stream branched off from the reaction container. The cell consists of a cell body (14) and cell covers (15, 16), with inflow and outflow pipes (17, 18) and support (19) for fixing cell in the spectrometer. The cell chamber consists of a bore (20) with cut out portions (2) for receiving a crystal plate (11) and sealing supports. The crystal plate (11) is held free from tension inside the throughflow cell and the sample stream flows over the crystal plate in a direction substantially parallel to the crystal surface. The measuring light enters the sloped off end faces of the crystal plate (11), is propagated inside the plate by total reflection against the surfaces, and leaves through a similarly sloped off surface at the opposite end. The intensity of the emergent light depends on the physical conditions at the optical phase boundary of the crystal plate surfaces (11a, 11b). If in the course of a chemical reaction the reaction mixture is caused to flow continuously over the crystal plate (11), the progress of the reaction can be followed by means of IR spectroscopy by the on-line process.