KILOMETER PATHLENGTH FOURIER-TRANSFORM INFRARED SYSTEM FOR STUDY OF TRACE POLLUTANTS IN AMBIENT AND SYNTHETIC ATMOSPHERES

A Fourier-transform infrared system operable at pathlengths up to 2km has been constructed for the detection and measurement of trace contaminants in the ambient atmosphere and in controlled smog formation studies. The long optical path is achieved by the use of an eight-mirror multiple reflection cell with a 22. 5-m base path. The design, construction and use of this novel folded-path optical system are described in detail. In preliminary ambient air measurements at Riverside, California, ppb concentrations of formaldehyde, nitric acid, formic acid and ammonia (in addition to O//3 and PAN) were measured in ambient air.