Pressure induced reactivity of solid CO by FTIR studies

Area of Science:

• Materials Science
• Chemical Physics
• Spectroscopy

Background:

• Investigating pressure-induced reactions is crucial for understanding material behavior under extreme conditions.
• Carbon monoxide (CO) reactivity is often influenced by light, complicating studies of intrinsic pressure effects.

Purpose of the Study:

• To investigate the pressure-induced reactivity of carbon monoxide (CO) across a wide temperature range (100-400 K).
• To differentiate the effects of pressure (P), temperature (T), and light (hν) on CO reactions.
• To identify a new instability boundary for CO reactions unaffected by photoactivation.

Main Methods:

• Fourier-transform infrared (FTIR) spectroscopy was used to monitor the reaction.
• Infrared sensors measured pressure changes.
• Experiments were conducted in the absence of light (hν) to isolate pressure and temperature effects.

Main Results:

• A novel instability boundary for CO reactivity was established, independent of photoactivation.
• Product formation was primarily dependent on temperature, with minor variations across different crystal phases (epsilon, delta, beta).
• Below 300 K, amorphous polycarbonyl chains with anhydride groups formed. Above 300 K, decarboxylation occurred, yielding carbon dioxide and epoxy rings.

Conclusions:

• Temperature is the dominant factor controlling the products of pressure-induced CO reactions, rather than crystalline phase.
• The solid product readily reacts with atmospheric moisture, forming carboxylic groups irreversibly.
• This research provides a fundamental understanding of CO behavior under pressure and temperature, crucial for materials science and chemical physics.