X-ray induced synthesis of a novel material: Doped Polymeric Carbon Monoxide
Polymeric carbon monoxide (poly-CO) can be produced by pressurizing CO at pressures above 5 GPa. The reddish-yellow waxy material is very unstable and decomposes into graphite and CO2 in a matter of days and is of interest as a potentially powerful energetic material (e.g. rocket fuel). It is also highly photosensitive. We have succeeded in producing a variant of poly-CO which we call “doped poly-CO” by irradiating a relatively stable material (strontium oxalate powder) with synchrotron-produced hard x-rays (>7 keV) at ambient and high pressures. We suspect that the sequence of x-ray induced reactions:
SrC2O4 + hυ → SrCO3 + CO
n(CO) → poly-CO
Here, we consider SrCO3 as the dopant. This novel material appears to be very stable and does not decompose over periods of at least one year. It also traps CO2 inside it for extremely long periods of time (> 1 year). We have produced doped poly-CO using different cations (Mg, Ca, etc) and using varying pressures. The synthesized products are somewhat varied (see figure below). It is our hope that this stable material may have some industrial importance as a possible wide band gap semiconductor or as a nonlinear optical material. Beyond this, certain critical questions are addressed in this research pertaining to x-ray induced polymerization, the surface composition of Mars, and the possible interstellar origins of life which will be discussed.