HR: 09:45h
AN: A51H-07    [Abstracts]
TI: Broadband Cavity Enhanced Absorption Spectroscopy: an in-situ DOAS for Atmospheric Measurements
AU: * Langridge, J M
EM: jml44@cam.ac.uk
AF: University Of Cambridge, University Chemical Laboratory Lensfield Road, Cambridge, CB2 1EW, United Kingdom
AU: Le Crâne, J
EM: jpgml2@cam.ac.uk
AF: University Of Cambridge, University Chemical Laboratory Lensfield Road, Cambridge, CB2 1EW, United Kingdom
AU: Ball, S M
EM: sb263@le.ac.uk
AF: University of Leicester, Department of Chemistry, Leicester, LE1 7RH, United Kingdom
AU: Jones, R L
EM: rlj1001@cam.ac.uk
AF: University Of Cambridge, University Chemical Laboratory Lensfield Road, Cambridge, CB2 1EW, United Kingdom
AB: From the processing of natural and anthropogenic emissions to the nucleation of new aerosol particles, tropospheric chemistry is driven by species present at trace concentrations. Field based observations provide the means to study complex trace gas processes in-situ, and advancements in understanding are often driven by developments in instrumentation that push forward the limits of sensitivity, target selectivity and deployment flexibility. In this work we present an ultra-sensitive optical instrument for quantification of a wide range of atmospheric trace gas components. The instrument is based upon a broadband variant of cavity enhanced absorption spectroscopy (BBCEAS) using high intensity light emitting diode sources, a short (1.1 m) high finesse optical cavity and wavelength resolved CCD detection. The BBCEAS approach enables measurements akin to those of traditional DOAS to be made in-situ and at high temporal resolution. This is important for the study of short lived species which show high spatial and temporal variability. In addition, the instrument offers deployment flexibility for field studies, being well suited for use on a range of platforms including aircraft, ships and vehicles. In this paper the instrument design and principles of operation will be described in detail, with particular attention being given to description of the calibration system. The performance of the instrument will be presented using results from a number of recent field and laboratory based studies. Most notably these include ppt level measurements of NO3 and N2O5 in coastal environments, ppt level detection of IO formed in reactor experiments from the oxidation of molecular iodine emitted from marine algae and lab based experiments showing sub ppb level detection of nitrous acid.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting