Ultraviolet absorption cross-sections of hot carbon dioxide

The temperature-dependent ultraviolet absorption cross-section for CO2 has been measured in shock-heated gases between 1500 and 4500 K at 216.5, 244, 266, and 306 nm. Continuous-wave lasers provide the spectral brightness to enable precise time-resolved measurements with the microsecond time-response needed to monitor thermal decomposition of CO2 at temperatures above 3000 K. The photophysics of the highly temperature dependent cross-section is discussed. The new data allows the extension of CO2 absorption-based temperature sensing methods to higher temperatures, such as those found in behind detonation waves.