Photoelectron-photofragment coincidence studies of NO ^--X clusters (X = H ₂O, CD ₄)

The dissociative photodetachment of NO ^-(H ₂O)and NO ^-(CD ₄) anion clusters was studied at 775 nm (1.60 eV) using photoelectron-photofragment coincidence spectroscopy. The correlation between the photoelectron and photodetached neutral spectra indicates vibrational excitation in the recoiling NO neutral fragments from NO-(H ₂O), with a progression consistent with vibrational excitation up to v(NO) = 3 in the products. The correlation remains when D ₂O is substituted for H ₂O, implying the NO vibrational mode plays a role in the dissociation coordinate of the complex. In contrast, no correlation was observed between photoelectron kinetic energy and kinetic energy release from NO ^-(CD ₄). Consideration of the maximum available kinetic energy allows the binding energies to be detemined as 0.57 and 0.07 eV for NO ^-(H ₂O) and NO ^-(CD ₄), respectively.