A schematic vibrational-energy-level diagram of CO2. The states drawn in black and grey are bright and dark states, respectively, of Raman spectroscopy.
The cubic (Pa3) structure of solid CO2 (phase I). Drawn are 27 unit cells each containing four molecules in which dimers are treated quantum mechanically.
The pressure dependence of the molar volume of solid CO2. The experimental data are taken from Refs. 37 and 38 .
The pressure dependence of the IR and Raman band positions. The calculations (blue) are based on MP2/aug-cc-pVDZ and experimental data (red and grey) are taken from Refs. 10 and 14 .
The calculated and observed Raman spectra of solid CO2 in the librational region. The calculated spectrum (blue) was obtained as the Gaussian convolution with a full width at half maximum (FWHM) of 10 cm−1 of the calculated histogram (also blue) at 4.0 GPa, whereas the observed (red) from Ref. 10 was obtained at 4.5 GPa.
The pressure dependence of the Raman spectra of solid CO2 in the symmetric-stretching (Fermi-resonance) region. The experimental spectra (red) are the Gaussian convolution with a FWHM of 8.3 cm−1 of the peak positions and intensities that have been interpolated from the experimental data in Ref. 10 . The calculated spectra (blue) are also the Gaussian convolution with a FWHM of 8.3 cm−1.
The C–O bond length (r C–O), lattice constant (a), and molar volume (V) of solid CO2 at 0 GPa.
The cohesive energy (in kJ mol−1) of solid CO2 at 0 GPa with (ΔU 0) and without (ΔU e) the zero-point vibrational energy contribution.
The harmonic frequencies (ν in cm−1) and relative intensities (I) of the IR- (ungerade) and Raman-active (gerade) lattice vibrations of solid CO2 at 0 GPa. The intensities of the gerade modes are relative to that of the E g mode and those of the ungerade modes are relative to the higher-frequency F u mode.
The frequencies of gaseous and solid CO2 (in cm−1).
Article metrics loading...
Full text loading...