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| Titel |
Interaction of NO2 with TiO2 surface under UV irradiation: measurements of the uptake coefficient |
| VerfasserIn |
A. Zein, Y. Bedjanian |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 2 ; Nr. 12, no. 2 (2012-01-20), S.1013-1020 |
| Datensatznummer |
250010544
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| Publikation (Nr.) |
 copernicus.org/acp-12-1013-2012.pdf |
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| Zusammenfassung |
| The interaction of NO2 with TiO2 solid films was studied under UV
irradiation using a low pressure flow reactor (1–10 Torr) combined with a
modulated molecular beam mass spectrometer for monitoring of the gaseous
species involved. The NO2 to TiO2 reactive uptake coefficient was
measured from the kinetics of NO2 loss on TiO2 coated Pyrex rods
as a function of NO2 concentration, irradiance intensity (JNO2
= 0.002–0.012 s−1), relative humidity (RH = 0.06–69 %),
temperature (T = 275–320 K) and partial pressure of oxygen (0.001–3 Torr).
TiO2 surface deactivation upon exposure to NO2 was
observed. The initial uptake coefficient of NO2 on illuminated
TiO2 surface (with 90 ppb of NO2 and
JNO2≅0.006 s−1)
was found to be γ0 = (1.2±0.4) ×10−4
(calculated using BET surface area) under dry conditions at T = 300 K. The
steady state uptake, γ, was several tens of times lower than the initial one,
independent of relative humidity, and was found to decrease in the presence
of molecular oxygen. In addition, it was shown that γ is not linearly
dependent on the photon flux and seems to level off under atmospheric
conditions. Finally, the following expression for γ was derived,
γ = 2.3×10−3 exp(−1910/T)/(1 + P0.36) (where P is O2
pressure in Torr), and recommended for atmospheric applications (for any RH,
near 90 ppb of NO2 and JNO2 = 0.006 s−1). |
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