Fig. 5: Global analysis of the photoinduced mid-IR absorption changes of the isolated carbonmonoxy α chains in the region of ground-state bleach at the parallel, perpendicular, and magic angle polarization settings.
From: Direct observation of two-channel photodissociation of carbon monoxide from the hemoglobin subunits
a Global SVD of the spectra associated with the intermediate species evolving in the first 100 picoseconds after the photoexcitation. b Global SVD of the spectra associated with the intermediate species evolving over a timescale ranging from nanoseconds to hundreds of microseconds. Global SVD in (a), as in (b), was performed on the global data matrix composed of data obtained at three polarization settings. In (a), as in (b), the time-dependent amplitudes (V1) of the first basis spectrum, multiplied by the first singular value (s1), at three polarization settings were globally fitted to eqn (S5) with the lifetime distribution g(logτ) being the same at all these polarization settings, the initial anisotropy r0 (eqn (S6)) being the global parameter (see Supplementary Note 2 for details). Additionally, at the global fitting in (b), the rotational correlation time τrot (eqn (S6)) was taken as a global parameter. In (a) and (b), the time-dependent amplitudes s1V1 and their global fit obtained with the simultaneous analysis of the data under all the polarization settings are plotted as symbols and the solid lines, respectively. The data obtained at three polarization settings are color-coded: 0° (red), 54.7° (blue), and 90° (green). In all insets, the first basis spectrum (U1) and its fit with a sum of Voigt functions are shown in black as circles and the solid line, respectively. The ground-state FTIR absorption spectrum normalized to an arbitrary value is shown as the orange solid line for comparison. In the inset of (b), the ground-state FTIR absorption spectrum is additionally offset for clarity. The vertical gray line shows the position of the vibrational band of CO in the A1 conformational substate. Note the difference in the range for the horizontal axis in (a) and (b). Source data are provided as a Source Data file.
