Diode laser-based gas analyser for the simultaneous measurement of CO<sub>2</sub> and HF in volcanic plumes

Abstract

Abstract. A portable analyser is described for simultaneous detection of CO 2 and HF emitted by volcanoes and fumaroles. The system is based on two fibre-coupled distributed feedback lasers and only one multipass cell, and provides the absolute concentration values of the two gases, without requiring a calibration procedure, at a maximum rate of 4 Hz. The spectrometer can operate both in a closed-cell configuration and in an open-cell set-up, with the latter mitigating problems associated with chemisorption of the HF molecule. The concept, practical realization and laboratory performance of the device are presented, together with results from a first test campaign measuring volcanic gases emitted from the crater of Vulcano, Italy. We obtained an in-field sensitivity of 320 ppb for CO 2 and 20 ppb for HF at 2 s integration time.

Identification and Control Method of Temperature and Pressure Control System in Methane Isotope Measurement System

“…instruments, scholars at home and abroad are constantly improving the detection limit and stability of measurement, and have done a lot of research on the influence of temperature and pressure on measurement accuracy [13][14][15][16]. At present, the manufacturers who can provide spectral measurement instruments include ABB of Canada [17][18] and Picarro of the United States [19][20][21][22], whose products cover all kinds of greenhouse gas detection in various industries. In China, Hangzhou Focused Photonics Inc, Anhui Institute of Optics and Precision Machinery of the Chinese Academy of Sciences and Ningbo Haierxin Optoelectronic Technology Co., Ltd. can provide TDLAS gas analysis instruments in small batches.…”

Dioxin and Related Compound Detection: Perspectives for Optical Monitoring

“…Typically, narrow laser sources are used for spectroscopy of simple molecules in gas phase, like CO2, H2S, CO, HF with a large variety of experimental setups [43,44,45,46,47,48,49].…”

Ground-Based Remote Sensing and Imaging of Volcanic Gases and Quantitative Determination of Multi-Species Emission Fluxes

“…At volcanoes hot lava can be used as source of radiation (e.g., [36], see below), which-according to our definition-would be classified as passive absorption spectroscopy. (b) Tunable Diode laser spectroscopy (TDLS), which (e.g., [37][38][39]) is a variety of dispersive spectroscopy where a narrow-band emitting light source (i.e., a semiconductor laser) is rapidly wavelength modulated in order to sweep across an absorption line of the gas to be measured. The original, rather unreliable lead salt diodes are now replaced by much more stable (though still expensive) quantum cascade laser diodes [40,41].…”