Measurements of near-UV absorption spectra of acetone and 3-pentanone at high temperatures

Gas phase acetone and 3-pentanone absorption cross sections have been measured in shock-heated gases in the wavelength range from 220 to 340 nm (the n−π* system) at temperatures between 300 and 1100 K. Absorption measurements using a deuterium source and a kinetic spectrograph enable accurate, broadband measurements of absorption cross sections while simultaneously observing decomposition at elevated temperatures, thus minimizing errors due to product formation. The absorption spectra of both ketones increase in strength and shift to the red with increasing temperature. The spectra are fitted to a parameterized Gaussian curve to allow for calculations of the cross sections as a function of temperature and wavelength.