Frequency comb based spectrometer for in situ and real time measurements of IO, BrO, NO₂, and H₂CO at pptv and ppqv levels.
We report an instrument designed for trace gas measurement of highly reactive halogenated radicals, such as bromine oxide and iodine oxide, as well as for nitrogen dioxide and formaldehyde. This compact and robust spectrometer relies on an alternated injection of a frequency-doubled femtosecond radiation at 338 and 436 nm into two parallel high-finesse cavities, for measuring BrO + H(2)CO, and IO + NO(2), respectively. The transmission of the broadband radiation through the cavity is analyzed with a high resolution, compact spectrograph consisting of an echelle grating and a high sensitivity CCD camera. The transportable instrument fits on a breadboard 120 × 60 cm size and is suitable for in situ and real time measurements of these species. A field campaign at the Marine Boundary Layer in Roscoff (in the northwest of France, 48.7°N, 4.0°W) during June 2011 illustrates the outstanding performance of the instrument, which reaches a bandwidth normalized minimum absorption coefficient of 1.3 × 10(-11) cm(-1) Hz(-1/2) per spectral element, and provides detection levels as low as 20 parts per quadrillion of IO in 5 min of acquisition.
University Grenoble 1/CNRS, LIPhy UMR 5588, Grenoble, F-38041, France.
Roberto
R
Grilli
Guillaume
G
Méjean
Samir
S
Kassi
Irène
I
Ventrillard
Chadi
C
Abd-Alrahman
Daniele
D
Romanini
D000393:Air Pollutants / Q000032:analysis*; D017605:Bromine Compounds / Q000032:analysis*; D004867:Equipment Design; D005557:Formaldehyde / Q000032:analysis; D005602:France; D017613:Iodine Compounds / Q000032:analysis*; D057230:Limit of Detection; D009585:Nitrogen Dioxide / Q000032:analysis*; D010087:Oxides / Q000032:analysis*; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods*
D000393:Air Pollutants; D017605:Bromine Compounds; D017613:Iodine Compounds; D010087:Oxides; C521367:bromine monoxide; D005557:Formaldehyde; D009585:Nitrogen Dioxide