Ab initio interaction energies for with OH in its ground and excited electronic states are depicted as a function of intermolecular separation (adapted from Ref. 29). Slices of the potentials and the CIs that couple them are shown for collinear [solid (blue)] and T-shaped [dashed (red)] configurations. The asymptote for possible reaction products is also indicated.
Transmission function of filters used for detecting emission from high rotational levels of the OH state. Emission lines and corresponding Einstein coefficients (Ref. 42) for OH (0,0) transitions originating from OH (, , 15, and 24) levels.
Pseudo-first-order decay rates and corresponding lifetimes for OH (upper panel) and (lower panel) as a function of rotational level . The experimentally observed total decay rates (, open circles) along with radiative (, gray line) and predissociation (, black line) rates from Ref. 42 are used to derive collision-induced decay rates (, filled circles). The reported uncertainty on is the standard deviation from repeated measurements.
Nascent quantum state distribution of OH products arising from quenching of OH (, ) by under single-collision conditions. The fractional population of OH in (circles) and (triangle) are shown with uncertainties derived from repeated intensity and fluorescence lifetime measurements. The and -doublet components are depicted with filled and open symbols, respectively. The population for each rotational state represents the average of the and manifolds. The lines through the data are best fit functions described in the text.
Comparison of quantum state distributions for OH products arising from quenching of OH (, ) by and under single-collision conditions. Fractional population is shown for quenching by (●) and , with the product distribution reported previously in Refs. 25 and 26 (◼) and additional measurements for higher (◻). Only population for the -doublet of the manifold are shown for reasons of clarity.
Cartesian representation of the energy difference gradient (left panel) and interstate coupling (right panel) vectors used to characterize the CI for the system in the near-linear configuration. Note that the lengths of the and vectors are scaled by factors of 10 and 30, respectively, to enable direct comparison with the system (Fig. 2 of Ref. 31).
Topography of the cone of intersection in the vicinity of the near-linear CI is depicted for the [filled (blue)] and [open (red), adapted from Ref. 31] systems. Energies of the and states are shown as a function of . The angle defines a loop around the cone at a constant distance of from the CI based on the parameters given in Table III. Here, , 90°, 180°, and −90° correspond to , , , and , respectively.
Optical filtering schemes for the OH PSD and branching fraction measurements.
OH product vibrational distribution obtained experimentally by summing over rotational and fine-structure distributions and predicted from Franck–Condon factors.
CI parameters (a.u.) for the and systems in the vicinity of the linear ( or ) configuration. The magnitude of the and vectors are given by and , while the tilt of the cone of intersection along these directions is defined by and , respectively. The energies of the upper and lower states in the region of the CI (see Fig. 7) can be evaluated directly from these parameters .
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