A diode laser spectrometer for the in situ measurement of the HNO3 content of polar stratospheric clouds

Year: 1999

Authors: Toci G., Mazzinghi P., Vannini M.

Autors Affiliation: Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze, Italy; Instituto di Elettronica Quantististica, Firenze, Italy

Abstract: A new instrument realized for measuring the HNO3 concentration in air is described. The device is a midinfrared absorption spectrometer based on a tunable diode laser and a multipass absorption cell. The instrument is specifically designed for airborne operation on board the M-55 Geophysica, in the frame of the Airborne Polar Experiment project, taking into account all the related environmental and operational constraints. The device is part of a complete measurement package for the measurement of the chemical content of the polar stratospheric clouds and other atmospheric aerosols. Furthermore, it can be used as a stand-alone detector of molecular trace gases. The primary purpose of the instrument is to perform in situ diagnostic measurements in the upper troposphere-lower stratosphere. Design criteria include a new optical setup, one much less sensitive to the vibration and thermal stresses with respect to the conventional diode laser spectrometers.
Furthermore, the authors developed a novel detection scheme for quicker acquisition and better signal-to-noise ratio. This paper reports calibration and testing measurements, including a detection lower limit both for the HNO3 and ammonia. This last gas is used as a wavelength and absorption reference.

Journal/Review: JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY

Volume: 16 (10)      Pages from: 1295  to: 1302

KeyWords: in situ measurement; laser method; nitric acid; polar stratospheric cloud; spectrometer
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