An Absolute C02 Monitor with Extremely High Accuracy

Carbon dioxide is monitored with high precision at hundreds of monitoring stations, world-wide. Those measurements rely upon frequent calibration using high pressure gas cylinders, which must be certified and then shipped to remote locations. Current calibration procedures are both labor intensive and expensive. Continuous monitoring of CO2 at remote locations presents particularly difficult calibration problems. Thus, there is a pressing need for an affordable, highly accurate (at least 1 part in 3000) carbon dioxide monitor for the ambient atmosphere as called out in the DOE SBIR solicitation Topic 43b, Item 2. In addition to being extremely accurate, this instrument must operate unattended for several months or more. We propose an absolute CO2 monitor which is based on spectroscopic measurements and sealed reference volumes of CO2. The instrument will compare laser spectroscopic measurement of a flowing sample cell to a permanently sealed quartz reference cell. The spectroscopic measurement is based on the integrated absorbance of an isolated, temperature independent rovibrational line of CO2 near 2.7