Charge Transfer to Solvent Dynamics at the Ambient Water/Air Interface

Abstract

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

New Insights into the Charge-Transfer-to-Solvent Spectrum of Aqueous Iodide: Surface versus Bulk

“…21,22 Phasesensitive transient second harmonic generation spectroscopy measurements by Verlet and coworkers reveal that the lowest CTTS state of aqueous iodide at the air/water interface is asymmetrically solvated in the plane of the surface and that the electron solvation dynamics at the interface are very similar to those observed in the bulk, although slightly faster. 23,24 The asymmetry of the lowest CTTS wavefunction is also predicted by Bradforth & Jungwirth, 21 arising from the thermal fluctuation of the local solvation environment. Their calculation suggests that the lowest CTTS states comprise a mixture of valence s (~30%), diffuse s (~50%) and p (~17%) type orbitals.…”

“…30,31 There is an instantaneous asymmetry to the local solvation environment in bulk, 21 but upon moving to the interface, iodide is expected to lose ~1-2 water molecules from its first solvation shell and thus experiences far greater asymmetry. 23,[51][52][53] In addition, at the high salt concentrations used in the ESFG experiments ([NaI]bulk = 5 M), solvent-shared and contact ion-pairs, solvent orientational effects, and electric double-layer formation are expected. [54][55][56] The external electric field experienced by the iodide ion at the interface strongly perturbs the symmetry and relaxes the 1PA and 2PA parity selection rules established for bulk aqueous iodide.…”

Probing the Birth and Ultrafast Dynamics of Hydrated Electrons at the Gold/Liquid Water Interface via an Optoelectronic Approach

“…An anisotropic second harmonic generation (SHG) response was previously reported at the air–water interface for a charge transfer to solvent (CTTS) state, prior to the proper photodetachment of the electron from the iodide center. 54 The anisotropy in a CTTS system at the air–water interface thus appears early and switches to an isotropic response with the electron photodetachment while, in comparison, the electron at the metal/water interface starts with an isotropic signal in the hot state and later displays anisotropy. Conversion from an isotropic to an anisotropic response at different stages of the relaxation dynamics can be rationalized as the consequence of the nature of the optical transitions taking place at the metal interface for different states of the hydrated electron, as will be discussed in detail below.…”

Time-resolved second harmonic generation with single-shot phase sensitivity

“…This enabled us to probe the charge-transfer-to-solvent dynamics of photoexcited iodide at the water/air interface. 33 However, the method proved to be sensitive to alignment, and suffered from long acquisition times because of the requirement to measure dynamics at various phase positions. The long acquisition times made the experiment susceptible to long-term laser power and alignment drifts.…”