(Top) Experimental LIF spectrum of the B 2Σ+ ← X 2Σ+ transition of the CN radical produced by the 266 nm photolysis of ICN in a Ar flow (15.8 slm) measured for a delay Δt = 30 μs. (Bottom) Simulated non-saturated LIF spectrum of the CN radical at the rotational temperature of 483 K and the vibrational temperature of ∼1400 K with a gaussian instrumental profile with a full width at half maximum of 0.045 Å using the LIFBASE program. 25
Experimental integrated LIF signal of the CN(v = 0) (upper panel) and CN(v = 1) (lower panel) at T R = 680 K in Ar (15.8 slm) in absence of co-reactant.
Experimental LIF signal (black solid curve) of the CN radical at T R = 483 K in Ar (15.8 slm) in the presence of [C2H6] = 104 × 1013 molecules cm−3 and the fitting curve (red solid curve).
Second order plots for the reaction between the CN radical and C2H6 for T R = 483 K and T R = 1088 K.
Boltzmann plot derived from the analysis of the LIF spectrum displayed in Figure 1 .
Rate coefficients for the reaction of CN(X 2Σ+) with ethane, C2H6, as a function of temperature. This work: (solid red circle). Yang et al. 28 between 185 and 739 K: (△). Hess et al. 29 over the 294–736 K range: (×). Herbert et al. 30 over 297–694 K range: (+). Balla et al. 31 using PLP-LIF and diode absorption spectroscopy over the 292–1409 K: (⊕). Copeland et al. 32 over the 279–452 K range: (⋆). Atakan and Wolfrum 33 over the 294–984 K: (⋄). Bullock and Cooper 34 over the 300–415 K range: (○). Sims et al. using a supersonic uniform flow reactor (CRESU): 35 (solid black circle). The full line represents theoretical calculations by Georgievskii and Klippenstein 36 over the 20–1140 K range combining VRC-TST and 2TS. The dotted line corresponds to the fit of our data over the 298–1116 K range.
Rate coefficients for the reaction of CN(X 2Σ+) with ethylene, C2H4, as a function of temperature. The filled red circles (•) represent the experimental results obtained with the high temperature flow tube. The empty blue triangles (△) correspond to the data obtained by Yang et al. 28 between 181 and 740 K, whereas the black empty circles (○) were measured by Herbert et al. 30 using a flow tube/PLP-LIF apparatus over the 295–698 K range. Finally, the black full circles (•) represent measurements performed by Sims et al. using a supersonic uniform flow reactor (CRESU). 35 The dotted line corresponds to the fit of our data over the 298–1116 K range.
Coordinate system of the CN–X (X = He, Ar) complex.
Contour plot of the V 0, 0(R, θ) matrix element of the CN–He (upper panel) and CN–Ar (lower panel) interaction potentials for vibrationally elastic scattering as a function of R and θ. The energies are in cm−1.
Contour plot of the V 0, 1(R, θ) matrix element of the CN–He and CN–Ar interaction potentials for vibrationally inelastic scattering as a function of R and θ. The energies are in cm−1.
Energy variation of the CN–He and CN–Ar vibrationally elastic and inelastic cross sections.
Temperature variation of the CN–He and CN–Ar vibrationally elastic and inelastic rate coefficients.
Calculated characteristic 1 → 0 vibrational relaxation time of the CN radical with different collisional partners according to SAPT calculations (solid line) for Ar and He, and to the SSH model (dotted line) for Ar, He, N2, and H2 for a pressure of 405 Pa.
Calculated relaxation time τ(s) of CN(v = 1) with Ar vs. collisional partner number density and gas temperature. The current experimental conditions are also represented by the thick red line.
Calculated relaxation time τ(s) of CN(v = 1) with He vs. collisional partner number density and gas temperature. The conditions encountered in the circumstellar envelope of IRC +10216 (black solid line), fuel/air/He combustion flames (red solid line), and CRESU flows (blue solid line) are also reported.
Rate coefficients of the CN + C2H4 and CN + C2H6 reactions.
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