Room-Temperature Cavity Ring-Down Spectroscopy of Methylallyl Peroxy Radicals

2019 ◽  
Vol 123 (16) ◽  
pp. 3510-3517 ◽  
Author(s):  
Md Asmaul Reza ◽  
Hamzeh Telfah ◽  
Raobo Xu ◽  
Jinjun Liu
Keyword(s):  
Room Temperature ◽  
Peroxy Radicals ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down

Cavity ring-down spectroscopy of transient O2-O2 dimers

2001 ◽  
Vol 79 (4) ◽  
pp. 773-781 ◽  
Author(s):  
H F Tiedje ◽  
S DeMille ◽  
L MacArthur ◽  
R L Brooks
Keyword(s):  
Cross Sections ◽  
Room Temperature ◽  
Cavity Ring Down Spectroscopy ◽  
Selection Of ◽  
Cavity Ring Down

Cavity ring-down spectroscopy has been used to obtain the spectra of transient (O2)2 at 577 and 629 nm, at room temperature and pressures ranging from about 0.25 to 10.0 atm. A selection of these spectra are displayed showing the overlapping monomer and dimer features. Pressure-dependent cross sections have been obtained and Rayleigh extinction has been observed. The derived band parameters are compared to recent results from others. PACS Nos.: 33.20kf, 33.70Fd

Direct Observation of Tetrahydrofuranyl and Tetrahydropyranyl Peroxy Radicals via Cavity Ring-Down Spectroscopy

2018 ◽  
Vol 9 (16) ◽  
pp. 4475-4480 ◽  
Author(s):  
Hamzeh Telfah ◽  
Md Asmaul Reza ◽  
Jahangir Alam ◽  
Anam C. Paul ◽  
Jinjun Liu
Keyword(s):  
Direct Observation ◽  
Peroxy Radicals ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down

scholarly journals Airborne measurement of peroxy radicals using chemical amplification coupled with cavity ring-down spectroscopy: the PeRCEAS instrument

2020 ◽  
Vol 13 (5) ◽  
pp. 2577-2600 ◽  
Author(s):  
Midhun George ◽  
Maria Dolores Andrés Hernández ◽  
Vladyslav Nenakhov ◽  
Yangzhuoran Liu ◽  
John Philip Burrows
Keyword(s):  
Oxidation Mechanism ◽  
Peroxy Radical ◽  
Ambient Air ◽  
Peroxy Radicals ◽  
Free Troposphere ◽  
Cavity Ring Down Spectroscopy ◽  
Airborne Measurements ◽  
Dual Channel ◽  
Unpaired Spin ◽  
Cavity Ring Down

Abstract. Hydroperoxyl (HO2) and organic peroxy (RO2) radicals have an unpaired spin and are highly reactive free radicals. Measurements of the sum of HO2 and RO2 provide unique information about the chemical processing in an air mass. This paper describes the experimental features and capabilities of the Peroxy Radical Chemical Enhancement and Absorption Spectrometer (PeRCEAS). This is an instrument designed to make measurements on aircraft from the boundary layer to the lower stratosphere. PeRCEAS combines the amplified conversion of peroxy radicals to nitrogen dioxide (NO2) with the sensitive detection of NO2 using cavity ring-down spectroscopy (CRDS) at 408 nm. PeRCEAS is a dual-channel instrument, with two identical reactor–detector lines working out of phase with one another at a constant and defined pressure lower than ambient at the aircraft altitude. The suitability of PeRCEAS for airborne measurements in the free troposphere was evaluated by extensive characterisation and calibration under atmospherically representative conditions in the laboratory. The use of alternating modes of the two instrumental channels successfully captures short-term variations in the sum of peroxy radicals, defined as RO2∗ (RO2∗=HO2+∑RO2+OH+∑RO, with R being an organic chain) in ambient air. For a 60 s measurement, the RO2∗ detection limit is < 2 pptv for a minimum (2σ) NO2 detectable mixing ratio < 60 pptv, under laboratory conditions in the range of atmospheric pressures and temperatures expected in the free troposphere. PeRCEAS has been successfully deployed within the OMO (Oxidation Mechanism Observations) and EMeRGe (Effect of Megacities on the transport and transformation of pollutants on the Regional and Global scales) missions in different airborne campaigns aboard the High Altitude LOng range research aircraft (HALO) for the study of the composition of the free troposphere.

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