Kinetics and Photochemistry Laboratory

Left:  Fast-flow reactor with long-path absorption cell coupled to a high-resolution FTIR spectrometer for studies of gas-phase reactions and mechanisms over the temperature range 220 – 300 K.
Right:  Laser photolysis/laser-induced fluorescence apparatus for measurements of rate constants for reactions of the OH (hydroxyl) radical with atmospheric molecules.

The JPL Kinetics and Photochemistry Laboratory (JKPL) studies elementary chemical reactions in the atmospheres of Earth and planetary systems. Most of these reactions involve highly reactive free radicals important in the odd oxygen, hydrogen, nitrogen, halogen and sulfur families. These radicals, including those formed from the decomposition of industrial chemicals such as chlorofluorocarbons (CFCs), catalyze the destruction of stratospheric ozone, and cause the well-known Antarctic Ozone Hole. They are also important in the formation of excess ozone and other harmful air pollutants in the lower atmosphere, and produce photochemical smog in cities and downwind areas.

In JKPL, we use state-of-the-art techniques to measure rate coefficients of elementary gas-phase reactions, and quantum yields of  photochemical processes under conditions of pressure and temperature relevant to atmospheric modeling. Lasers of many types are used to initiate chemical reactions and probe the reaction kinetics in real time using fluorescence, cavity ringdown, and long-path and cavity-enhanced absorption. Other analysis methods include molecular beam mass spectroscopy, high resolution Fourier Transform Infrared (FTIR) spectroscopy and matrix isolation spectroscopy. The laboratory also measures UV-visible-IR absorption cross sections and spectroscopic line parameters of atmospheric molecules.

The overall objective of JKPL is to provide laboratory data that will support models that assess issues such as stratospheric ozone depletion and the coupling between air quality and climate change. JKPL coordinates the activities of the NASA Panel for Data Evaluation, a group of specialists in laboratory kinetics and photochemistry who publish a periodic critical evaluation of data for use in atmospheric models and other studies. These evaluations includes recommended rate coefficients, equilibrium constants, photochemical parameters, aerosol chemistry parameters and thermodynamic data for modeling the atmospheres of Earth and planets. The evaluation is available for download on the Panel’s web site.

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