Measurement of Absolute O2(1△) Concentration Using Improved Infrared Radiation-Calorimetry Method

The absolute O2 （1Δ）concentration measurement performed for a singlet oxygen generator（SOG）by using the infrared radiation-calorimetry method is reported with a detailed discussion of its principle and related technique. The influence of O2 （1Δ）gas temperature variation is considered and the corresponding correction has been made，which is neglected by the previous researchers and may cause a significant error in the case of measurement for the large O2 （1Δ）flowrate. Furthermore，an automatically balanced Wheatstone bridge circuit，which is necessary for O2 （1Δ）detection on the SOG of short operation period，is designed and tested by measuring the heat capacity of oxygen. The final error analyses give out a total relative error of ±16% for the O2 （1Δ）concentration，which mainly arises from the measurements of infrared radiation，pressure and temperature at the optical cell.