Description: Fuer die og Untersuchungen ist geplant, eine kombinierte LIF/UV-VIS-Absorptions-Anordnung aufzubauen. Die Erzeugung der verschiedenen Radikale soll durch Excimer-Laserphotolyse geeigneter Radikalvorlaeufer erfolgen. IO-Radikale koennen sehr empfindlich mit Hilfe der Laser-induzierten Fluoreszens-(LIF)-Technik nachgewiesen werden. Die Anregung erfolgt dabei im A2II3/2 (v'=2) kleiner -- X2II3/2 (v''=0) - Uebergang mit Fluoreszenz aus v'' = 3. BrO bzw CIO-Radikale besitzen ausgepraegte UV-Bandenspektren mit relativ grossen Absorptionskoeffizienten im nahen UV. Damit ist es moeglich, diese Spezies durch zeitaufgeloeste UV-Absorptionsspektroskopie zu detektieren. Durch Einsatz einer 'gatebaren' CCD-Kamera wird erreicht, dass die Absorption der Edukte (CI2, Br2 etc) separiert werden koennen.
Types:
SupportProgram
Origins:
/Bund/UBA/UFORDAT
Tags:
Fluoreszenz
?
Brom
?
Chlor
?
Oxid
?
Absorption
?
Messverfahren
?
Stratosphäre
?
Laboruntersuchung
?
Excimer-Laserphototolyse
?
Fluoreszenztechnik
?
Kinetik
?
LIF-Technik
?
Radikal [Chemie]
?
UV-Absorptionsspektroskopie
?
atmospheric-chemistry
?
free-radicals
?
kinetics
?
laser-spectroscopy
?
Region:
Nordrhein-Westfalen
Bounding boxes:
6.76339° .. 6.76339° x 51.21895° .. 51.21895°
License: cc-by-nc-nd/4.0
Language: Deutsch
Organisations
Time ranges:
1997-04-01 - 2000-03-31
Alternatives
-
Language: Englisch/English
Title: Laboratory Investigations of the Kinetics of Reactions of BrO and IO Radicals Relevant for the Stratosphere
Description: Ozone destruction in the polar stratosphere is largely related to the chemistry of halogen oxides (XO). Whereas there is evidence from both field and laboratory studies that under conditions of high chlorine activation ozone destruction proceeds mainly by the involvement of CIO radicals only (CIOx/CIOx-mechanisms) this is not the case for lower levels of chlorine activation under which the CIOx/BrOx interaction is of comparable importance. Moreover recent evidence also suggest that substantial contributions may als arrive by CIOx/IOx and BrOx/IOx interactions. In order to quantify the possible extent of these interactions to ozone depletion in the lower stratosphere detailed studies of iodine chemistry in this part of the atmosphere is reguired. This involved studies of IOx interconversion reactions such as IO and NO gleich I and NO2, IO and IO gleich products as well as studies of IOx reactions involving IOx reservoir species, viz. IO and NO2 and M gleich IONO2 and M, OH and HI gleich H2O and I. Moreover, the kinetics and product distributions of CIOx/IOx and BrOx/IOx reactions also need detailed investigations. In this project the technique of laser photolysis in combination with either LiF or laser-long-path-absorption will be used to study the kinetic of the above reactions over a wide range of pressure and temperature. In addition, a gated CCD camera will be employed to identify various product channels of these reactions and to quantify their relative contributions. Emphasis will bei placed on these product channels that lead to chain propagation and therefore enhanced ozone destruction efficiency.
https://ufordat.uba.de/UFORDAT/pages/PublicRedirect.aspx?TYP=PR&DSNR=56410
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