Experimental
How to produce O(1D)
The O(1D) was generated in the reaction cell by the photolysis of N2O at 193 nm using an ArF laser.N2O + hν193 nm → N2 + O(1D)Because the translationally hot O(1D) atom is quickly thermalized by the collisions with buffer gas, the hot atom effect can be ignored under the present experimental conditions.How to detect O(1D), O(3P), CN(X 2Σ+), and NCO(X 2Π)
O(1D) and its quenched product O(3P) were detected by the laser induced fluorescence (LIF) method for the (3s 1D° − 2p 1D) transition at 115.22 nm and (3s 3S° − 2p 3P) transition at 130.22 nm, respectively.
The vacuum ultraviolet (VUV) wavelength of 115.22 nm and 130.22 nm were generated by frequency tripling (3ω) of a dye laser at 345.6 nm in Xe gas and by four-wave difference mixing (2ω1−ω2) using two dye lasers in Kr gas, respectively.
The CN(X 2Σ+) and NCO(X 2Π) radicals were also detected by the LIF method for the CN(B 2Σ+−X 2Σ+) transition around 390 nm and NCO(A 2Σ+−X 2Π) transition around 440 nm, respectively, using ultraviolet (UV) and visible (VIS) dye lasers.
Setup
Sample gas mixtures containing N2O as an O(1D) source, CF3CN or N2 as a reactant, and He as a buffer were flowed slowly through the evacuated reaction cell. The probe laser beam for the detection of O(1D) or reaction products was also introduced in the reaction cell after the delay.
To determine the reaction rate constants, the reaction time was defined as this delay time, t, between the photolysis and probe laser pulses.
The quantum yield of the quenching was measured by comparison between the O(3P) signal intensity formed in the present reaction and that in the reaction
N2 + O(1D) → N2 + O(3P)in which the quantum yield is defined as unity.
