Two different routes for ejection of hydrated electrons by photoexcited CuCl 2 -and CuCl 3 2-have been observed: (1) a prompt (i.e. within the 5-ns laser pulse width) ejection directly from the charge-transfer excited states (characterized as CTTS or Rydberg states), and (2) a delayed ejection, with lifetimes of up to 105 ns, from the triplet states of the two complexes. These two processes have rather high quantum yields: 0.30-0.40 for the prompt ejection and 0.25-0.33 for the delayed ejection for the chlorocuprate(I) complexes. The delayed ejection process is the primary decay route for the two triplet species, 3 CuCl 2 -and 3 CuCl 3 2-, which are formed by intersystem crossing from the charge-transfer excited states formed by absorption of light by the bis-and triscoordinated complexes in equilibrium in the ground state. Both of the chlorocuprate triplet excited states are weakly luminescent species. The triplet tris species, 3 CuCl 3 2-, has a strong absorption band at 390 nm ( ≈ 27 000 M -1 cm -1 ), and the biscoordinated species, 3 CuCl 2 -, probably absorbs in the same region as well. Other intermediates such as Cu(0) complexes and Cl 2 •-radicals have also been observed as decay products. Prompt and delayed electron ejection has also been observed in CuBr 3 2-with quantum yields of 0.25 and 0.18, respectively. A mechanism that incorporates a triplet excited state equilibrium is invoked to account for these observations.
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