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(e)Discharge-flow

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Website: http://www.iupac-kinetic.ch.cam.ac.uk/. See website for latest evaluated data. Datasheets can be downloaded for personal use only and must ...

IUPAC Subcommittee on Gas Kinetic Data Evaluation Data Sheet R_Oxygen_10

    Website: http://www.iupac-kinetic.ch.cam.ac.uk/. See website for latest evaluated data. Datasheets can be downloaded for personal use only and must not be retransmitted or disseminated either

    electronically or in hardcopy without explicit written permission. thThis datasheet updated: 16 November 2006.

    HCO + O CO + HO 22

     -1;H? = -139.0 kJ?mol

    Rate coefficient data

    3-1-1k/cm molecule s Temp./K Reference Technique/

    Comments

    Absolute Rate Coefficients -12(5.6 ? 0.9) x 10 300 Shibuya et al., 1977 FP-AS (a) -12(4.0 ? 0.8) x 10 300 Clark et al., 1978 PLP-AS -12(3.8 ? 1.0) x 10 300 Nadtochenko et al., 1979 FP-AS -11 -(0.4 ? 0.3)5.5 x 10 T 298-503 Veyret and Lesclaux, 1981 FP-AS (b) -12(5.6 ? 0.6) x 10 298 -12(4.65 ? 0.6) x 10 295 Langford and Moore, 1984 PLP-AS (c) -12(4.2 ? 0.7) x 10 300 Gill et al., 1981 FP-AS -12(5.1 ? 1.0) x 10 296 Temps and Wagner, 1984 DF-LMR -111.3 x 10 exp[-(204 ? 180)/T] 295-713 Timonen et al., 1988 PLP-MS (d) -126.2 x 10 295 -123.2 x 10 exp(87/T) 200-398 Stief et al., 1990 DF-MS (e) -124.3 x 10 298 -124.3 x 10 298 Dóbé et al., 1995 DF-LMR (f)

    -12200-298 Nesbitt et al., 1999 DF-MS (g) (2.2) x 10 exp[(170 22)/T]

    -12298 (4.0 0.6) x 10 -12295 Ninomiya et al., 2000 PLP-AS (h) (5.9 0.5) x 10 -12Hanoune et al., 2001 PLP-AS (i) (5.0 0.7) x 10 2942 -12(5.6 ? 0.3) x 10 296 DeSain et al., 2001 PLP-LIF (j) -12(5.9 ? 0.1) x 10 295 Colberg and Friedrichs, 2006 PLP-AS (k)

Relative Rate Coefficients -12(5.7 ? 1.2) x 10 297 Washida et al., 1974 RR (l)

    -12295 Ninomiya et al., 2000 RR (m) (6.3 1.5) x 10

    Comments

(a) Flash photolysis of CHCHO-O mixtures; HCO monitored by time-resolved absorption 32

    at 613.8 nm. There was no pressure effect on k for pressures of up to 690 mbar (520 Torr)

    of He.

    (b) Flash photolysis of HCHO and CHCHO; HCO was monitored by laser absorption at 3

    614.5 nm at total pressures of 17 mbar to 660 mbar (13 Torr to 500 Torr). (c) Pulsed laser photolysis of HCHO or (CHO) with monitoring of HCO by absorption at 2

    total pressures of up to 1330 mbar (1000 Torr).

    (d) Pulsed laser photolysis of CHCHO; HCO was monitored by photoionization MS at 3

    pressures of 0.69 mbar to 1.22 mbar (0.52 Torr to 0.92 Torr).

    (e) Discharge-flow system. HCO radicals were generated from Cl + HCHO and monitored

    by photoionization MS.

    (f) HCO radicals were generated by the reaction of F atoms with HCHO. The total pressure

     radicals was measured relative to the formation was 1.7 mbar of He. The yield of HO2

    yield of HO radicals from the reaction of F atoms with HO, and determined to be 1.00 222

    ? 0.05.

    (g) Same experimental technique as in comment (e). The rate constant measured at 398 K

    seems to indicate a small positive temperature dependence for T > 300 K in qualitative

    agreement with Timonen et al., 1988.

    (h) Pulsed laser photolysis of CHCHO at 266 nm; HCO was monitored by cavity ring-down 3

    spectroscopy at 613.5 nm at total pressures of 5.32-13.3 mbar (4-10 Torr) of N. 2

    (i) Pulsed laser photolysis of a mixture of HCO and Cl at 355 nm with monitoring of the 22

    R5 or R6 transition in CO by tunable diode laser absorption in the range 6.65-63.84 mbar 15-3(6-48 Torr). Only data with [O] > 5 x 10 molecule cm have been used in the analysis. 2

    (j) Pulsed 193 nm laser photolysis of CCl or CClF in the presence of CHO or direct 432

    photolysis of CHO or CHCHO at 284 and 305 nm, respectively, coupled to cw LIF of 23

    HCO at 258 nm in the range 10.5-40 mbar He. No kinetic isotope effect for DCO + O 2

    has been observed (k/k = 1.00 ? 0.07) in contrast to theoretical predictions by Hsu et HD

    al., (1996). Small positive temperature dependence of k in the range 296 673 K.

    (k) 193 nm photolysis of glyoxal ((CHO)) in 50-200 mbar Ar in a slow flow reactor coupled 2

    to FM absorption spectroscopy of HCO at 614.752 nm. The rate constant was obtained

    from observed differences between HCO concentration-time profiles measured with and

    without added O (245-3985 ppm) using numerical modelling. Secondary reactions of 2

    photolytically generated H atoms were taken into account. A small positive temperature

    dependence observed in the range 7391108 K.

    (l) Discharge flow system with HCO being monitored by photoionization MS. k measured -103-1-1relative to k(O + HCO products) = 2.1 x 10 cm molecule s (measured in the

    same apparatus) by observing the effect of O on [HCO] in a flowing mixture of O-CH; 2224-2k/k(O + HCO) = (2.74 ? 0.21) x 10.

    (m) Based on the ratio of the rate constants k (HCO + O)/k (HCO + Cl) = 0.85 0.02 22

    measured in a smog chamber coupled to FTIR detection. The absolute value of k (HCO + -123Cl) used to put the relative rate on an absolute basis was (7.4 1.7) x 10 cm molecule 2-1s.

    Preferred Values

     -123-1-1k = 5.2 x 10 cm molecule s at 298 K with a small negative temperature dependence

    in the range 200 to 300 K.

Reliability

    ;log k = ? 0.15 at 298 K.

    ;(E/R) = ? 150 K.

Comments on Preferred Values

    The preferred value of the rate coefficient at 298 K is the average of the room-temperature rate coefficients of Shibuya et al. (1977), Veyret and Lesclaux (1981), Langford and Moore (1984), Temps and Wagner (1984), Timonen et al. (1988), Stief et al. (1990), Dobé et al. (1995), Nesbitt et al. (1999), Ninomiya et al. (2000), Hanoune et al. (2001), DeSain et al. (2001) and Colberg and Friedrichs (2006). The earlier studies performed in static reactors (Clark et al. (1978), Nadtochenko et al. (1979), Gill et al. (1981)) were not taken into account. Taken together, the temperature-dependent studies of Veyret and Lesclaux (1981), Timonen et al. (1988), Stief et al. (1990), and Nesbitt et al. (1999) show that the rate coefficient of this reaction has a small negative temperature dependence over the range 200 to

    298 K on the order of -1.4 kJ/Mol or less. In the range 300 to 650 K the activation energy seems to be close to zero and increases up to 13 kJ/Mol in the range 650 to 1100 K (Colberg and Friedrichs, 2006) within the error limits of the measurements. High level ab initio calculations predict barriers of 12.5 and 9.5 kJ/mol for the direct abstraction channel vs.

    , respectively (Martinez-Avila et al. (2003)). The formation of the addition complex HCO-O2

    transition state for the four-center elimination separating the addition complex and the HO + 2

    CO products lies below the entrance channel.

    References

    Clark, J. H., Moore, C. B., and Reilly, J. P.: Int. J. Chem. Kin. 10, 427, 1978. Colberg, M., and Friedrichs, G.; J. Phys. Chem. A 110, 160, 2006.

    DeSain, J. D., Jusinski, L. E., Ho, A. D., and Taatjes, C. A.: Chem. Phys. Lett. 347, 79, 2001. Dobé, S., Wagner, H. G., and Ziemer, H.: React. Kinet. Catal. Lett., 54, 271, 1995. Gill, R. J., Johnson, W. D., and Atkinson, G. H.: Chem. Phys. 58, 29, 1981. Hanoune, B., Dusanter, S., ElMaimuni, L., Devolder, P., and Lemoine, B.: Chem. Phys. Lett. 343, 527, 2001.

    Hsu, C.-C., Mebel, A.. M., and Lin, M. C.: J. Chem. Phys. 105, 2346, 1996. Langford, A. O. and Moore, C. B.: J. Chem. Phys. 80, 4211, 1984.

    Martinez-Avila, M., Peiro-Gardia, J., Ramirez-Ramirez, V. M., and Nebot-Gil, I.: Chem. Phys. Lett. 370, 313, 2003.

    Nadtochenko, V. A., Sarkisov, O. M., and Vedeneev, V. I.; Dokl. Phys. Chem. 244, 152, 1979. Nesbitt, F. L., Gleason, J. F., and Stief, L. J.: J. Phys. Chem. A 103, 3038, 1999. Ninomiya, Y., Goto, M., Hashimoto, S., Kagawa, J., Yoshizawa, K., Kawasaki, M., Wallington, T. J., and Hurley, M. D.: J. Phys. Chem. A 104, 7556, 2000.

    Shibuya, K., Ebata, T., Obi, K., and Tanaka, I.: J. Phys. Chem. 81, 2292, 1977. Stief, L. J., Nesbitt, R. L., and Gleason, J. F.: Abstracts of papers presented at the International Symposium of Gas Kinetics, Assisi, Italy, Sept. 1990.

    Temps, F., and Wagner, H. Gg.: Ber. Bunsenges. Phys. Chem. 88, 410, 1984. Timonen, R. S., Ratajczak, E., and Gutman, D.: J. Phys. Chem. 92, 651, 1988. Veyret, B. and Lesclaux, R.: J. Phys. Chem. 85, 1918, 1981.

    Washida, N., Martinez, R. I., and Bayes, K. D.: Z. Naturforsch. 29a, 251, 1974.

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