Effects of vibrational excitation on the F + H2O → HF + OH reaction: dissociative photodetachment of overtone-excited [F–H–OH]– † †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc03364h Click here for additional data file.

Photodetaching vibrationally excited FH2O– channels energy into the reaction coordinate of the F + H2O reaction, as shown in this joint experimental-theoretical study.

In Figures S2 and S3, the calculated HF and OH vibrational state distributions on the X/A state PES are given in several energies for the vibrational ground and excited states of the anion, respectively. In both cases, the HF vibrational state distribution is inverted when excited states are energetically accessible, while little vibrational excitation is found for the OH product. Figure S2 shows that parent anion vibrational excitation leads to larger populations in both the HF(v=0) and HF(v=2) states. This trend is consistent with both experimental 1-3 and theoretical observations [4][5][6][7] in the F + H2O bimolecular reaction, and is a level of detail that cannot be extracted from the experimental PPC spectrum.
In Figure S4, the total photoelectron spectrum is compared with the dissociation flux after the ~1 ps propagation. This shows that that the dissociation captured by the propagation is disproportionally from high energy resonances. In other words, there remains a significant population of lower energy longer-lived resonances that dissociate on a timescale beyond 1 ps.
In Figure S5, the calculated internal energy distributions of the HF + OH and F + H2O channels are shown at two energies for both the vibrational ground and excited state of the anion.

II. Experiment
The energetics of various channels are summarized in Table S2. Figure S6 shows PPC difference spectra at IR photon energies of 2885, 2872 and 2900 cm -1 , and a null difference spectrum, to provide a measure of the magnitude of the effect. The 2885 cm -1 spectrum exhibits the strongest effect of vibrational excitation, although the 2872 cm -1 spectrum also shows statistically significant enhancement above a total energy of 1.0 eV. A measure of the statistical error in the 2885 cm -1 difference spectrum can also be examined in Figure S7, which shows the no-IR PPC spectrum as the number of events N(eKE,KER) in frame (a) and the Poisson error N(eKE,KER) 1/2 in frame (b).

II.1. Stable Photoelectron Spectra and Estimation of Fraction of Vibrational Excitation
The photoelectron spectra for stable products, events that lead to the detection of one photoelectron and a single particle at the center-of-mass of the incident ion beam, are measured in these experiments as well. In the previous study of cold F¯(H2O) anions in ref.
8, a product-channel complex was observed above the KE MAX UV limit (1.03 eV) as well as long-   Table S1. Numerical parameters (in a.u.) used in wave packet calculations. The HF+OH channel is described by diatom-diatom Jacobi coordinates and the F+H2O channel is described by (2+1) Radau-Jacobi coordinates.

Channels HF+OH F+H2O
Grid/basis ranges and sizes  Table S2. Experimentally determined total kinetic energy (eKE + KER) limits for accessible product channels for both UV-only and UV+IR DPD of F¯(H2O). The maximum kinetic energies are reported for neutral products formed in their ground rotational and vibrational states. Following Otto et al. 8 , KE′MAX for production of F + H2O + e-in the DPD of F¯(H2O) is determined from the measured dissociation energy F¯(H2O) → F¯ + H2O (ΔD o = 1.14 eV 9 , the photon energy (hνUV= 4.80 eV) and the electron affinity of the F atom (3.401 eV) 10 . KEMAX for production of HF(nHF=0) + OH(nOH=0) is determined by the reaction exoergicity of -0.76 eV based on heat of formation data in the Active Thermochemical Tables. 11 The product channel, HF + OH, is labeled using the notation (nHF, nOH) to indicate quanta of vibrational excitation. The UV+IR kinetic energy limits are found by adding the IR photon energy (hνIR= 0.36 eV, 2885 cm -1 ) to hνUV, under the assumption that the added IR photon energy may appear as product or photoelectron kinetic energy.      . Difference (IR -no-IR) PPC spectra recorded with hνUV= 4.80 eV at various IR photon energies, and a null difference PPC spectrum for F¯(H2O) dissociative photodetachment at top left. Spectra have been normalized to the number of events in the no-IR spectrum (or in the case of the null spectrum, the subtracted spectrum) to put them all on a common scale to see the relative effects. The grey and black solid lines indicate the energetic limits, KEMAX, for dissociation into HF + OH and F + H2O fragments, respectively, determined by the total photon energy hνUV + hνIR. The dashed lines indicate vibrationally excited product states as in the other PPC spectra. The blue areas indicate suppression and the red enhancement relative to the no-IR spectrum. In particular by examining the region above 0.6 eV, it can be seen that the 2885 cm -1 spectrum has the most significant signal, with the 2872 cm -1 spectrum also showing significant signal above 1.0 eV.  Blue and red areas indicate suppression and enhancement, respectively, relative to the no-IR spectrum. Solid and dashed vertical lines correspond to limits for dissociation to HF + OH and F + H2O, respectively. Error bars correspond to √ IR + no−IR for each bin. Figure S9. Simulated difference photoelectron spectrum for estimation of the fraction of vibrational excitation with the simple model where the UV + IR photoelectron spectrum was generated by summing the no-IR spectrum with the no-IR spectrum shifted by the IR photon energy as the pure IR contribution, scaled by the excitation fraction, f, such that IRmodel = f(IR) + (1-f)*(no-IR). The simulated difference spectrum shown here results from subtracting the no-IR spectrum from IRmodel: model= IRmodel -no-IR.