Quartz Lyman-α lamp coupled to the infrared cell via a MgF2 window. The mass spectrometer is located as shown.
Measured distribution of emitted power from Lyman-α source using a thermopile. The distribution shown by the black points is very strongly peaked in the forward direction and estimated to be cos300Θ, as shown by the red angular distribution.
SiO2 sample pressed into a tungsten grid stretched between two Ni clamps which are cooled by l-N2. The grid is at 45° to Lyman-α radiation and to the incident IR radiation.
Evolution of associated Si-OH···ON2 bands in the IR spectra during N2O adsorption on clean Si-OH.
Lyman-α induced decrease in integrated absorbance for N2O(g) (10 Torr, 300 K) modes ν1+ν3 and 2ν1. Here only 13% of N2O(g) has been consumed in the experiment.
Lyman-α photolysis of clean SiO2 containing only isolated Si-OH groups. The factor of 5 in the calculation is due to the approximation that only the outer 1/5 of the SiO2 surfaces receives Lyman-α radiation due to strong absorption and scattering.
A qualitative comparison of the infrared spectral evolution during the photodecomposition of N2O in the gas phase (300 K) and in the adsorbed phase (71 K). N2O4 species produced by the fragment combination are observed on the SiO2 surface while the gas phase measurements barely detect this species.
An example of quantitative measurements of the depletion of N2O on the SiO2 surface at 71 K during Lyman-α irradiation in three sequential experiments, I, II, and III. The shutter is alternatively opened and closed thereby turning the light on and off. Loss of absorbance occurs in vacuum by two processes: thermal and thermal + photodesorption of N2O (slopes m0 and m1).
An example of the production of N2O4, one of the combination products of photodecomposition of N2O adsorbed on SiO2.
Variation of average complex product enhancement ratio, , with the complexity of the combination products.
Photodissociation kinetic parameters.
Selectivity of combination processes.
Article metrics loading...
Full text loading...