Pressure conditions, diamond anvil cell

High-pressure experiments promise to provide insight into chemical reactivity under extreme conditions. For instance, chemical equilibrium analysis of shocked hydrocarbons predicts the formation of condensed carbon and molecular hydrogen.17 Similar mechanisms are at play when detonating energetic materials form condensed carbon.10 Diamond anvil cell experiments have been used to determine the equation of state of methanol under high pressures.18 We can then use a thermodynamic model to estimate the amount of methanol formed under detonation conditions.19... 

We have made direct optical observations and measmements of microbial activity at various pressures. As in the above experiments, we have used diamond anvil cells in combination with micro-Raman spectroscopy and optical microscopy to directly monitor their viability and metabolic activity at extreme conditions [58]. The following is an overview of these direct observations of microbial activity under extreme pressures and their implications for adaptive mechanisms of life (as we know it) on this planet. 

We have measured sound velocities of various supercritical fluid systems. An attempt to carry forward such measurements on higher temperature isotherms of formic acid was frustrated by chemical reaction toward products that may include carbon dioxide, carbon monoxide, water, hydrogen and differentiated solid-like products at even higher temperatures and pressures. Nonetheless, the diamond anvil cell provides a unique opportunity to study the chemistry and kinetics of fluids under extreme conditions. We also find that CH2O2 is present during the detonation of some common explosives. 

Understanding energy release in terms of thermodynamic cycles ignores the important question of the time scale of reaction. The kinetics of even simple molecules under high pressure conditions is not well understood. Diamond anvil cell and shock experiments promise to provide insight into chemical reactivity under extreme conditions. 

The spin and valence states of iron in the lower-mantle minerals have been investigated bya number of synchrotron X-ray and optical laser spectroscopic techniques in a high-pressure diamond anvil cell (DAC). Mossbauer spectroscopy has been instrumental in our understanding of this topic because this method is specific to Fe-containing minerals and provides hyperfine QS and CS parameters [5,19-22]. Specifically, synchrotron Mossbauer spectroscopy (SMS) with a highly intense and focused beam coupled with the X-ray transparent DAC permits in situ observations of the Mossbauer spectra with reasonable data collection times at extreme P-T conditions [20-22]. 

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