The thermal, electron and photon activation of methyl nitrite, CH3ONO,
adsorbed on Ag(111) has been examined. Thermally there is no dissocia
tion, and monolayers, which are weakly held, desorb at 131 K. Dissocia
tion occurs readily when adsorbed CH3ONO is irradiated with either 50
eV electrons or photons with energies higher than 3.4 eV (lambda<365 n
m). X-ray irradiation initiates dissociation and loss of N 1s and O 1s
intensity that is consistent with ejection of NO. The only product ej
ected during irradiation with ultraviolet photons is NO. The cross-sec
tion for disappearance of the CH3ONO, as measured by its post-irradiat
ion TPD peak area, is wavelength-dependent, generally rising with phot
on energy between 3.4 eV and the highest energy used here, 4.9 eV (lam
bda=254 mm). The cross-section is 0.26+/-0.04 x 10-18 cm(2) at 3.4 eV
and 1.15+/-0.1 x 10(-18) cm(2) at 4.9 eV. For 50 eV electrons, NO is a
lso dominant but is accompanied by small amounts of CH3, CH2O and CH3O
H. The initial cross-section for loss of CH3ONO is 5+/-1x10(-16) cm(2)
. Heating to 500 K after irradiation with electrons, X-rays or UV phot
ons, leaves a clean Ag(111) surface. Among the products desorbed after
photon or electron irradiation, methane and formaldehyde have been id
entified.