Trifluoronitrosomethane (CF 3 NO), which is readily photolyzed in the gas phase when exposed to light in the 600-700 nm portion of the spectrum, does not undergo significant photolysis when irradiated while adsorbed on sublimated films of alkali halides (NaCl, NaBr, KCl, KBr) at temperatures of 10-100 K. This quenching does not occur when the molecule is irradiated while adsorbed on argon films (thickness > 0.1 µm) or in multilayer coverage. Comparison of the quantum efficiencies for photolysis indicates that vibrational relaxation induced by surface phonons is primarily responsible for the alkali halide quenching, but lateral diffusion of the photofragments and/or excited-state molecules may also play a role in the kinetic scheme. The photochemistry was followed using infrared spectroscopy, providing the first vibrational characterization of adsorbed sub-monolayer CF 3 NO. A photodimer of CF 3 NO was also observed and vibrationally characterized on the argon films and on the overlayers. The NO stretching frequency for the dimer is significantly lower than had been previously reported for the N-nitritoamine photodimer {(CF 3 ) 2 NONO} and may indicate the existence of a second photodimer species. Adsorption potentials were calculated for various sites on the four alkali halide films. The lowest energy orientation in each case had the C-N bond parallel to the surface, aligned in the [110] direction. The vibrational spectra and thermal desorption curves are consistent with the calculated energies.

The infrared spectrum of trifluoronitromethane (CF3NO2) physically adsorbed on sublimated alkali halide (NaCl, NaBr, KCl, and KBr) films in submonolayer and multilayer coverages, and isolated in argon and nitrogen matrices, has been observed. The fundamental vibrations exhibit some surface-specific shifts, and there is indication that rotation about the CN bond is hindered upon adsorption. As in the gas phase, ultraviolet irradiation of the adsorbed species leads to the production of adsorbed carbonyl fluoride (CF2O), but an adsorbed FNO photoproduct was not observed, presumably lost to a secondary photolysis. Quantum efficiencies for photolysis were determined for submonolayer and multilayer species and were found to be independent of temperature (Φ = 0.20 ± 0.20 adsorbed; 0.29 ± 0.20 multilayer), reduced from that of the matrix-isolated species. These quantum efficiencies were used to determine rate constants for surface-induced relaxation of the adsorbate as a function of surface composition and temperature. Desorption isotherms for both CF3NO2 and CF2O were observed and fit to a first-order kinetic model of desorption, with activation energies of desorption of 14 ± 5 kJ mol-1 for CF3NO2 on the sodium salts, 16 ± 5 kJ mol-1 for CF3NO2 on the potassium salts, and 28 ± 6 kJ mol-1 for CF3NO2 desorbing from overlayers.