Observation of charge-transfer excited states in the I−⋅CH3I, I−⋅CH3Br, and I−⋅CH2Br2SN2 reaction intermediates using photofragmentation and photoelectron spectroscopies

Abstract

Photoelectron spectra of the I⁻⋅CH₃I, I⁻⋅CH₃Br, and I⁻⋅CH₂Br₂ complexes each display a relatively sharp main feature shifted from that of I⁻ by the expected binding energies of the ion–dipole bound negative ions. We observe narrow photofragmentation bands in both I⁻⋅CH₃I and I⁻⋅CH₂Br₂ upon excitation just above the photodetachment thresholds (≊3.5 eV), whose envelopes closely resemble their photoelectron spectra.