Oxalate geometry and the vibrational energy levels in the asymmetric stretch region. (a) and (b) energy diagram of two coupled vibrational transitions.
Synthetic scheme used to prepare C13-oxalate.
FTIR spectra of ∼0.1 M solution of C13-oxalate ion in D2O with solvent background subtracted. The open circles represent the experimental data points, whereas the line represents a model fit with Voigt profiles. The solid black line represents the fit and the dotted red and dashed green lines are its individual components.
Experimental pump-probe signals of the C13-oxalate ion. Top panel shows parallel polarization (XXXX) pump-probe spectra of 0.1 M oxalate ion in water at T = 0.35 ps. The middle and lower panels show the isotropic signal of the low frequency at photo-induced absorption band (1518 cm−1) and the high frequency at bleach band (1590 cm−1), respectively. Black open squares correspond to the experimental data and the red line to the fitting described in the text.
Experimental anisotropy dynamics of oxalate ion. Anisotropy of the low frequency at the new absorption band at 1518 cm−1 (top panel) and the high frequency at bleach/SE band at 1590 cm−1 (lower panel). Solid black lines correspond to the experimental data, and solid red and dashed blue are the fitted curves as described in the text.
Absorptive 2D IR spectra of C13-oxalate ion in D2O. 2D IR spectra for the XXXX (left column) and XXYY (right column) pulse polarizations at different waiting times: T = 0, 0.45, 1.5, and 2.15 ps. Black dashed line corresponds to the diagonal (ωτ = ω t ).
Vibrational population transfer of C13-oxalate in water. Experimental HTG signal for the ⟨XXXX⟩–3⟨XXYY⟩ in the cross-peak region at: 1510 cm−1 (top panel) and 1590 cm−1 (bottom panel). Open squares correspond to the experimental data and the red line to the fit with Eqs. (14) and (15) .
Slope versus waiting time for diagonal and cross-peaks. (a), (b), and (c) panels correspond to the slope of the low frequency diagonal peak, high frequency diagonal peak, and the right lower corner cross-peak, respectively. The filled squares are the experimental data points and the solid red line is the fit to a single exponential function.
Theoretical FFCF and FFXCF of the oxalate ion of the asymmetric stretch vibrational modes. The top and bottom panels correspond to the frequency–frequency autocorrelation and cross-correlation functions, respectively. Panels (a) and (b) correspond to the auto- and cross-correlation, respectively. The red lines correspond to the fitting with a sum of exponential functions (see text).
Time dependence of the population probabilities, Pi. Open squares and black lines represent the time evolution of the site populations with the single site as an initial condition. Filled triangles and red lines show the time dependence of the site populations for the eigenstate coefficient derived from the time averaged Hamiltonian.
Theoretical and experimental FTIR spectra of C13-oxalate ion in D2O. The open circles (bottom axis) represent the experimental data points, whereas the solid black, dashed red, and dotted blue lines (top axis) represent the total FTIR and the and components predicted by the theory, respectively.
Parameters of the population and anisotropy dynamics fit for the different parts of the transient spectrum.
Parameters of the experimental frequency auto- and cross-correlation functions.
Parameters of the theoretically predicted frequency auto- and cross-correlation functions.
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