CO2 in solid para-hydrogen: spectral splitting and the CO2···(o-H2)n clusters.

Area of Science:

• Spectroscopy
• Quantum Chemistry
• Materials Science

Background:

• Molecules doped in solid hydrogen often show complex spectral features.
• These structures are frequently misinterpreted due to various contributing effects.

Purpose of the Study:

• To elucidate the origins of complex spectral structures observed for carbon dioxide (CO2) in solid para-hydrogen (p-H2).
• To establish a model system for understanding molecular behavior in solid hydrogen matrices.

Main Methods:

• Potential energy simulations of CO2 in a para-hydrogen matrix.
• Experimental spectroscopy using various CO2 isotopologues and ortho-hydrogen (o-H2) concentrations.
• Analysis of spectral dynamics and experiments with oxygen (O2) codoping.

Main Results:

• Spectral features were assigned to CO2···(o-H2)n clusters.
• Energy level splitting due to CO2 molecule alignment in the matrix was identified.
• O2 codoping facilitated ortho-to-para hydrogen conversion, supporting assignments.

Conclusions:

• The spectral features of CO2 in p-H2 provide insights into cluster formation and molecular alignment.
• These spectral signatures can serve as a novel method for monitoring temperature and o-H2 concentration in solid p-H2.