Electrode reactions involving electronically excited states of molecules

Abstract

Calculations are presented concerning two aspects of the electrode reactions of molecules M* in electronically excited states. Firstly, the current which would flow through an electrode is computed for the experimental arrangement in which M* is generated by irradiation of a solution of the ground-state molecules M through the electrode, which is assumed to be potentiostatically controlled in a region of potential where only M* is electroactive. Secondly, the rate of electrogeneration of M* is calculated, assuming the potential of the electrode to be switched instantaneously from one at which an anion M" is formed at a diffusion-controlled rate to one at which oxidation of Mto M* is feasible. In each calculation the quenching of M* to M by electron exchange with the electrode is allowed for by using for this purpose arecently derived for mulation of an electrochemical rate constant valid at high overpotentials.

Factors that Control the Direction of Excited-State Electron Transfer at Dye-Sensitized Oxide Interfaces

“…In Marcus–Gerischer theory, electron transfer occurs between isoenergetic discrete states of the sensitizer [ W ( E )] and the continuum of states of the oxide [ g ( E )]. ,, The rate constant for electron transfer ( k et ) is determined by the electrode/molecule coupling matrix element ( H ab ) and the energetic overlap between g ( E ) and W ( E ) (eq ). For injection, the shaded excited-state donor distribution of RuP 3+/2+* has good overlap with the unfilled states of all the oxides, consistent with the rapid injection measured here, k inj > 10 8 s –1 . ,, As the applied potential ( V app ) was raised, the injection yields decreased. For TiO 2 |RuP and SnO 2 |RuP, the applied potential where injection began to measurably decrease aligned well with potentials at which occupation of the metal oxide acceptor states resulted in a smaller energetic overlap with the excited-state sensitizer.…”

“…For injection, the shaded excited-state donor distribution of RuP 3+/2+ * has good overlap with the unfilled states of all the oxides, consistent with the rapid injection measured here, k inj > 10 8 s −1 . 12,39,63 As the applied potential (V app ) was raised, the injection yields decreased. For TiO 2 |RuP and SnO 2 |RuP, the applied potential where injection began to measurably decrease aligned well with potentials at which occupation of the metal oxide acceptor states resulted in a smaller energetic overlap with the excited-state sensitizer.…”

Stabilization of AgI's polar surfaces by the aqueous environment, and its implications for ice formation

“…Following Fraux and Doye, 42 who also used the TIP4P/2005 model in their study of ice formation at AgI, the non-electrostatic interactions between the AgI ions and the water molecules were described by a LJ potential centered on the oxygen atoms of the water molecules, using parameters originally from Hale and Keifer. 45 Lorentz-Berthelot mixing rules were applied to obtain non-electrostatic interactions between NaCl and AgI. Parameters for non-electrostatic interactions are reported in Tables S2 and S3. Following Zielke et al , 41 we used Burley's lattice parameters (a = 0.4592 nm, c = 0.7510 nm) for AgI.…”

“…7,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] The INP we investigate here is AgI, which is perhaps the most potent inorganic INP currently known. [19][20][21]44 In particular, we consider the basal Ag-(0 0 0 1) and I-(0 0 0 1) crystal faces-the focus of numerous [40][41][42][43][45][46][47] studies-and exploit recent advances in simulation methodology [48][49][50][51] to better understand plausible mechanisms by which the aqueous environment can stabilize these interfaces.…”

“…Owing to its excellent ice nucleating properties, the AgI/H 2 O interface has been the focus of many previous studies. [19][20][21][22][40][41][42][43][45][46][47] From a simulation perspective, however, it is only recently that computational resources have been such that ice formation at AgI has been tackled directly. Zielke et al , 41 and Fraux and Doye investigated ice formation at different crystal faces of AgI.…”