Vibrational relaxation of NO in collisions with atomic oxygen and chlorine

Abstract

The vibrational relaxation of NO(X 2 n) in the v = 0, I, and 2 states in collisions with Ar, NO, N0 2 , and electronic ground state 0 and CI atoms has been studied in shock waves. 0 and CI atoms were produced in the thermal dissociation ofN0 2 or N 2 0 at T"",2700 K, and ofCINO at T"",1700 K, respectively. Both atoms were found to be very efficient catalysts for vibrational energy transfer to NO. The relaxation rates observed suggest a mechanism involving bound (N0 2 )* and (CINO)* collision complexes.

Cooling Mechanisms of the Planetary Thermospheres: The Key Role of O Atom Vibrational Excitation of CO2 and NO

“…However, a recent quasiclassical trajectory (QCT) calculation [21] over the ONO potential energy surfaces (PES), based on the assumption that only the two attractive of a total of 18 PES contribute to the vibrational relaxation process, and an experimental measurement [22] have given the room temperature values of this rate coefficient equal to 2.8x10 À11 cm 3 s À1 and 2.4(AE 0.5) Â 10 À11 cm 3 s À1 , respectively-less than half Fernando and Smith's [20] value. While the experimental values for this rate coefficient are available at room temperature and at 2700 K, [23] the QCT values are available for 100 K T 2700 K. The experimental value at 2700 K agrees with the QCT calculation but associated error bar is so large that the only safe conclusion that may be drawn is that this rate coefficient does not have strong temperature dependence. There are several features of the QCT calculation that deserve mention: a) The calculated rate coefficient k n1 in the 100 ± 2700 K temperature range is almost independent of temperature.…”

Vibrational relaxation of NO(v = 1) by oxygen atoms between 295 and 825 K

“…Rate coefficients k O ( v = 1) for the vibrational relaxation of NO( v = 1) by O atoms over the 200–2700 K temperature range. The experimental data are given by the shaded symbols, taken from the present results (circles), and from Dodd et al [1999a] (inverted triangle), Fernando and Smith [1979] (diamond), Lilenfeld [1994] (triangles), and Glanzer and Troe [1975] (square). The two Lilenfeld rate coefficients were calculated by averaging several values over the 200–250 and 290–330 K temperature ranges, respectively.…”

“…A single value of k O ( v = 1) = (5 ± 1) × 10 −11 cm 3 s −1 was quoted as the result over that temperature range. Using a shock tube apparatus, Glanzer and Troe [1975] measured k O ( v = 1,2) in the 2630–2790 K temperature range, obtaining (3.7 ± 1.7) × 10 −11 and (4.0 ± 1.7) × 10 −11 cm 3 s −1 for v = 1 and 2, respectively. Taken together with the present results, the experimental data suggest a limited temperature dependence for k O ( v = 1) over a wide range of temperature (see Figure 4).…”

Further insight into the tunneling contribution to the vibrational relaxation of NO in Ar

“…9 shows the corresponding plot of LZ k 10 (T) (dashed blue line in Fig. 9) over the temperature range 300 < T < 2000 K, drawn with the value of LZ A fitted such that the rate coefficient LZ k 10 (T) assumes a value LZ k 10 (T) T =1500 K = 5 × 10 −15 cm 3 s −1 which lies in the middle of the shock tube results (full red circles 1 and empty blue triangles 20 ). Also shown are experimental results near 300 K by LIF and IR-UV double resonance techniques (empty magenta square 18,19 ).…”