Infrared photodissociation of (NO)n+·X cluster ions (n ≤ 5)

Abstract

Measurements of the infrared photodissociation pathways and spectra of size-selected (NO)_n⁺X complexes, for n in the range 2–5, have been carried out using a line-tuneable CO laser (photon energy 1600–1800 cm⁻¹). X is one of Ar, Kr, Xe, O₂, CO₂, CH₃Cl, CF₄ or SF₆. Two photoinduced fragmentation pathways have been monitored as a function of radiation wavelength: the loss of NO and the loss of X. The photofragmentation patterns and branching ratios are influenced by two factors: (i) the value of n; and to a lesser degree, (ii) the nature of the atom/molecule, X. A limited number of IR spectra have been recorded for the dimer, (NO)₂⁺, in association with the rare gas atoms and CF₄; for the remaining examples, the trimer, (NO)₃⁺, appears to act as a stable core with a comparatively large infrared absorption cross-section at ca. 1720 cm⁻¹.