George Cody

The blend of organic chemistry and geology can address a broad range of scientific questions -- from understanding the processes of oil and gas generation to solving the mystery of the origin of biochemistry as it emerged from the molecular chaos of the primitive Earth. George Cody is an organic geochemist whose research focuses on devising a unified understanding of the controls on organic reactions within the solid Earth. He explores the roles that temperature, pressure, time, fluid composition, and mineral catalysis play in controlling organic reactions over time. Understanding these processes is a prerequisite to investigating larger issues that tie together the biological, physical, organic, and inorganic world of our planet.

The mechanisms that govern natural organic synthesis and reactions are not restricted to Earth, however. The presence of significant quantities of organic molecules found in certain types of meteorites indicates that the range of viable environments for organic synthesis is extremely broad. In collaboration with others at Carnegie, Cody is working on questions pertaining to the extent of organic synthesis within the presolar nebula and the synthesis and reaction during the subsequent planetary accretion. His specific focus is to characterize the extraterrestrial organic matter within carbonaceous chondritic meteorites. If organic synthesis and reaction are necessary for the emergence of life, then the range and limits of organic stability and reaction need to be defined to set criteria for determining the probability of life on other planets and beyond our solar system. To study organic chemistry in this context, Cody has joined with others at Carnegie to form one of the first groups in NASA's Astrobiology Institute.

A wide range of analytical methods is required to study organic molecules in complex systems. Over the past several years Cody has worked on a particularly promising device that uses a one-of-a-kind soft x-ray transmission microscope based on a synchrotron source. He has been using this instrument to characterize the chemistry of cell wall membranes in plants and to follow the evolution of the chemical differentiation over geologic time as these materials transform into fossil fuels.

Cody also led the effort at the Geophysical Laboratory to obtain a solid-state nuclear magnetic resonance (NMR) spectrometer -- an instrument used by scientists at both the Geophysical Lab and the Department of Terrestrial Magnetism at the Broad Branch Road campus. Solid-state NMR has recently evolved into one of the most versatile and powerful tools in solid-phase chemistry. The new equipment is used to address fundamental questions in organic geochemistry as well as questions in many other ongoing research areas.

Fig. 5. The molecular tapestry of 40-million-year-old wood is shown in this high-resolution x-ray image acquired with the scanning transmission microscope at the National Synchrotron Light Source. The spatial resolution of the image is 50 nm and sample thickness is 150 nm. Contrast is based on the distribution of a specific type of carbon, and this provides a high-resolution chemical "map" of carbon chemistry.