Optical cell for in situ vibrational spectroscopic measurements at high pressures and shear

A multi-purpose high-pressure and high temperature gas-flow cell for operando optical Raman spectroscopy

A multi-purpose in operando optical cell with temperature and gas pressure control is described. This device allows for in operando Raman spectroscopy measurements for different applications. Its original design includes a temperature control from room temperature up to 1000°C and a heating stage that provides uniform and stable thermal conditions. The pressure control of the cell ranges from 10^-1 Pa to 6 MPa, and it is compatible with different gases. Both oxidizing and reducing gases are allowed to pass through the sample surface under study. The device has been calibrated and applied to collect Raman spectra for different reaction systems under various operating temperatures and pressures.

Mechanochemical synthesis of glycine oligomers in a virtual rotational diamond anvil cell

Mechanochemistry of glycine under compression and shear at room temperature is predicted using quantum-based molecular dynamics (QMD) and a simulation design based on rotational diamond anvil cell (RDAC) experiments. Ensembles of high throughput semiempirical density functional tight binding (DFTB) simulations are used to identify chemical trends and bounds for glycine chemistry during rapid shear under compressive loads of up to 15.6 GPa. Significant chemistry is found to occur during compressive shear above 10 GPa. Recovered products consist of small molecules such as water, structural analogs to glycine, heterocyclic molecules, large oligomers, and polypeptides including the simplest polypeptide glycylglycine at up to 4% mass fraction. The population and size of oligomers generally increases with pressure. A number of oligomeric polypeptide precursors and intermediates are also identified that consist of two or three glycine monomers linked together through C-C, C-N, and/or C-O bridges. Even larger oligomers also form that contain peptide C-N bonds and exhibit branched structures. Many of the product molecules exhibit one or more chiral centers. Our simulations demonstrate that athermal mechanical compressive shearing of glycine is a plausible prebiotic route to forming polypeptides.