Mbar Chemistry: 

The goal of this project is to investigate new states of matter and novel phenomena in low-Z solids and fluids occurring at Mbar (or ~million atmospheres) pressures. At these conditions, the compression energy (PDV) of molecular solids often exceeds a 10 eV/atom or 100 KJ/mol, rivaling those of the most stable chemical bonds (a few tens to hundreds KJ/mol)- certainly enough to induce bond scissions leading to chemical changes.  Materials often transform into more compact structures with itinerant electrons and often unexpected states of high energy-density, superionic, superconducting and superhard solids.  Therefore, our research efforts are centered at: Discovery of new states of matter and novel phenomena Understanding the governing rules for pressure-induced phase transitions Exploiting fundamental understanding of materials meta/stabilities and collective behaviors of solids – critical issues in solid state transformations Helping establish new Periodic orders of solids at Mbar pressures.

This project is currently funded by NSF (DMR-0854618) on Mbar Chemistry: Novel State of Matter at Extreme Conditions.

References:

• Novel Extended Phases of Carbon Dioxide at High Pressures and Temperatures, Amartya Sengupta and Choong-Shik Yoo, Phys. Rev. B (2009) in print.
• High Energy Density Extended Solids, Choong-Shik Yoo, a plenary paper to the APS_SCCM (2009), in print.
• Six-fold Coordinated Carbon Dioxide VI, Valentin Iota, Choong-Shik Yoo, J. Klepeis, Jeni Zsolt, W. Evans, H. Cynn, Six-fold Coordinated Carbon Dioxide,  Nature Materials 6, 34 (2007).
• Evidence for a New Orientationally Ordered Phase and the Bandgap of Deuterium at High Pressure Determined by Coherent Antistoke Raman Spectroscopy at 300K, Bruce Baer, William Evans, Choong-Shik Yoo, Phys. Rev. Lett. 98, 235503 (2007) 
• Extended Networks of Nitrogen: Reddish Amorphous- and Transparent Cubic Gauche Nitrogen Polymers, Magnus J. Lipp, Jae-Hyun Klepeis, Bruce Baer, Hyunchae Cynn, William J. Evans, Valentin Iota, and Choong-Shik Yoo, Phys. Rev. B. 76, 14113 (2007).
• High Pressure Materials Research: Novel Extended Phases of Molecular Triatomics, C. S. Yoo, in Chemistry in Extreme Chemistry ch 5, p 165-189, edited by R. Manna (Elsevier, 2005).
• Disproportionation and other transformations of N2O at high pressures and temperatures to lower energy, denser phases, C. S. Yoo, V. Iota, H. Cynn, M. Nicol, J.-H. Park, T. Le Bihan, and M. Mezouar, J. Phys. Chem. B107 (24): 5922-5925 (2003).