PLIF signals from CN[, , (●) ] radicals as a function of time delay between the pulses from the pump and probe lasers in a mixture of a trace of NCNO in of 3:1 mixture of and at . The continuous curve shows the simulation for achieved by the procedure outlined in the text [Eqs. (2a) and (2b)]. The inset shows PLIF signals from CN[, , (●) ] generated in of pure at .
A plot of pseudo-first-order rate coefficients for the removal of CN(, , ) as a function of the concentration of included in at a total pressure of . Under these conditions rotational relaxation is very rapid and the gradient of the line corresponds to the second-order rate constant for reaction between and .
Plots of pseudo-first-order rate coefficients for the total removal of CN radicals from the rotational level in the state as a function of the total concentration of a 2:1 mixture of and . After correction for the effects of , the gradients yield the second-order rate coefficients for total removal (by rotational energy transfer and reaction) of CN from the specified rotational levels.
Comparison of the rate coefficients for total removal of CN radicals from specified rotational levels in collisions with (엯) and (●).
Double resonance spectrum obtained, following the excitation of CN to , , by scanning the wavelength of the probe laser with delay between the pump and probe laser pulses. The total pressure of the gas was . Insert (a) shows the time dependence of the PLIF signals from and and 2 following excitation of CN(, ) in the same gas mixture, with the vertical dashed line marking the time delay used to take double resonance spectrum. Insert (b) presents state-to-state rotational energy transfer rate coefficients derived by the procedure described in the text.
Comparison of the rate coefficients for total removal from selected rotational levels (엯) with the sums of the state-to-state rate coefficients for rotational energy transfer from the same set of levels (◻).
The main panel compares the rotationally state-selected rate coefficients for reaction between CN and (i.e., ) measured in the present work (●) and interpolated for other rotational levels (엯), assuming that the rotationally state-selected rate coefficients for reaction depend exponentially on , with the thermal rate constant (---) at and with (⋯) corresponding to the reaction rate based on the interpolated values. The insert shows (●) the contributions to the thermal rate constant from different CN rotational levels compared with a curve (——) showing the variation of the equilibrium rotational populations at .
State-to-state rate coefficients, , for the transfer of CN radicals from rotational levels to rotational levels in (, ) in collisions with at . Errors in the values of are given at the level of . Figures in brackets are values of estimated using the PGF analysis described in the text.
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