An airborne diode laser spectrometer for the simultaneous measurement of H2O and HNO3 content of stratospheric cirrus clouds

Year: 2002

Authors: Toci G., Mazzinghi P., Mielke B., Stefanutti L.

Autors Affiliation: Istituto Nazionale di Ottica Applicata (INOA), Largo E. Fermi 6, 50125 Firenze, Italy;
Istituto di Elettronica Quantistica, Consiglio Nazionale delle Ricerche (IEQ-CNR), Via Panciatichi 56/30, 50125 Firenze, Italy;
Istituto di Ricerca sulle Onde Elettromagnetiche, Consiglio Nazionale delle Ricerche, (IROE-CNR), Via Panciatichi 64, 50127 Firenze, Italy;
Licel GbR, Chausseestr 34/35,10115 Berlin, Germany

Abstract: We describe a tunable diode laser spectrometer for the in situ simultaneous detection of the nitric acid and the water vapour by means of high resolution absorption spectroscopy on rovibronic lines, using a single laser emitting in the mid-infrared (5.8 mum) and a multipass cell. The instrument was designed to be installed on a high altitude aircraft, as a part of a composite payload for atmospheric aerosol studies. The instrument design criteria are discussed and the expected performances are compared with results of laboratory and field operation. Due to the high chemical activity of HNO3, that makes difficult to use a reference cell, a fast sweep detection of direct absorption was used for the measurement. An absorption sensitivity of about 2 x 10(-4) was achieved with an integration time of 2.5 s, corresponding to a concentration of about 4 ppb of HNO3 in the cell and 0.1 ppb in the external aerosol. The data acquisition and processing techniques, based on the full molecular lineshape fitting are also shown and discussed. including some examples of the data acquired during the scientific flights. (C) 2002 Elsevier Science Ltd. All rights reserved.

Journal/Review: OPTICS AND LASERS IN ENGINEERING

Volume: 37 (5)      Pages from: 459  to: 480

More Information: This work was funded by the European Commission under the EU contracts ENV4 CT95 0039 (APE-CVI) and ENV4 CT97 00533 (APE-THESEO). The test campaigns were also funded by the Italian Space Agency (ASI) and by the Italian Project for Antarctic Research (PNRA). The APE-THESEO campaign occurred also in the frame of the European Science Foundation ESF APE programme. The authors are very grateful to Mr. Francesco Castagnoli, of IROE-CNR, for the mechanical design and construction of the TDL and of the whole CVI instrument, to Mr. Mauro Pucci, of IEQ-CNR, for the construction of all the TDL optical components, and to Mr. Pasquale Poggi of INOA, for his support for the instrument electronics. The hard work of Dr. Stefano Balestri, of APE Srl, in organising the test and scientific campaigns is also greatly acknowledged. We also wish to thank Dr. Kevin Noone and Dr. Johan Ström of the University of Stockholm for the construction of the sampling system and of the CVI probe.
KeyWords: Aerosols; Atmospheric measurements; Infrared spectrometers; Laser tuning; Measurement by laser beam; Semiconductor lasers; Spectrochemical analysis; Stratosphere; Absorption spectroscopy; Aircraft; Atmospheric aerosols; Clouds; Data acquisition; Laser beams; Laser tuning; Light emission; Nitric acid; Semiconductor lasers; Sensitivity analysis; Upper atmosphere; Water, Diode laser spectrometers, Infrared spectrometers
DOI: 10.1016/S0143-8166(01)00134-8

Citations: 10
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