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2P photon yield (P, T, humidity) = ?

2P photon yield (P, T, humidity) = ?. Direct measurements ‘’3D’’ exp. data. Kinetic model. Only electron impact excitation: Partial parameterization, with the p’. Measurement of the quenching rates. To measure the K q N 2 ( C 3 Π u , v = 0, 1) by N 2 (X) and O 2 (X) we use:.

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2P photon yield (P, T, humidity) = ?

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  1. 2P photon yield (P, T, humidity) = ? Direct measurements ‘’3D’’ exp. data Kinetic model Only electron impact excitation: Partial parameterization, with the p’ Measurement of the quenching rates

  2. To measure the Kq N2( C 3Πu, v = 0, 1) by N2(X) and O2(X) we use: Time resolved optical spectroscopy kq Effective decay rate, Reff High S/B Pulsed12 KeV electron beam High statistics Excitation method Gas purity

  3. Set up at the Technische Universität München Monochromator S20 PMT e-gun PC Stainless steel chamber Cooling head inside

  4. Electric valves MgF2 window Ceramic foil PT100 Cooling head

  5. Results

  6. N2 wavelength spectra @ 400 hPa Spectra recorded at the central wavelength of the bands with 1 nm resolution assure negligible contribution of the adjacent bands.

  7. Time spectra, 2P(0,0) [337,1 nm] Non - monoexponential (VR) Fitted range C = C0+Me-Reff t After pulses from PMT

  8. Effect of the vibrational relaxation on the fitting method Rel. exc. efficiencies from A. Morozov et al. Eur., Phys. J. D 33, 207–211 (2005). V.R. and quenching rates fromG. Dilecce et al. / Chemical Physics Letters 431 (2006) 241–246.

  9. 500 hPa for v’ = 0 250 hPa for v’ = 1 e.g. 200 hPa N2 + 10 hPa O2 e.g.‘’dry air’’ 85 hPa total pressure Pressure limits • Instrumental factors • Fitting method Pure N2 ~ 5 ns effective lifetime N2/O2 mixtures v’ = 0

  10. Pure nitrogen

  11. Effective decay rate v’ = 0, 1 vs. pressure at room temperature (298 K)

  12. Effective decay rate v’ = 0, 1 vs. temperature

  13. Quenching rates vs. temperature, v’ = 0 k(T)=k0(T/300)β M.M. Fraga et al. NIM A 597 (2008) 75–82 k0 = (1.24 ± 0.4)×10-11(cm3s-1) β = - 0.33 ± 0.06 β = - 0.37 ± 0.15 M.M. Fraga et al. NIM A 597 (2008) 75–82 Ref.* A. Morozov et al. Eur., Phys. J. D 46, 51–57 (2008).

  14. Quenching rates vs temperature, v’ =1 k1(T) = (2.25 ± 0.21) ×10-11 + (1.41 ± 0.78)×10-14×T Ref. *A. Morozov et al. Eur., Phys. J. D 46, 51–57 (2008).

  15. k0increases by 13 ± 3 % in the range 300 down to 210 K. k1decreases by 5 ± 2.5 % in the range 300 down to 210 K. Is it vibrational relaxation of v’ = 1 responsible for this difference?

  16. Nitrogen/Oxygen mixtures

  17. Effective decay rate v’ = 0 vs. O2 pressure at room temperature (298 K) p’ air = 15.89 ± 0.73 hPa M. Ave et al. NIM A 597 (2008) 41-45

  18. Effective decay rate v’ = 0 vs. temperature for several N2/O2 mixtures

  19. Temperature dependence of the quenching rate constant KN2(T) = 1.24 ×10-11 (T/300)-0.33 cm3s-1 r0 = 0.0279 ns-1

  20. kO2(T) = (25.7 ± 0.2) ×10-11 + (13 ± 6)×10-14×T

  21. The quenching rate constant of the N2(C 3Πu,v’ = 0) state by O2(X) decreases by (4 ± 2)% in the in the range 300 down to 210 K.

  22. In the following talk by M.M. Fraga these results will be used to evaluate the temperature dependence of the emission intensity in N2 and N2/O2 mixtures Thank you for your attention !

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