Darmstadt 2008 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 25: Laseranwendungen (Spektroskopie)

Q 25.7: Vortrag

Dienstag, 11. März 2008, 18:00–18:15, 3H

Evanescent-field-sensor for detection of CO₂ dissolved in water — •Rozalia Orghici, Ulrike Willer, and Wolfgang Schade — TU Clausthal, Institute of Physics and Physical Technologies, Leibnizstraße 4, 38678 Clausthal Zellerfeld

The increase of the carbon dioxide (CO₂) concentration in the earth atmosphere is considered to be one of the main factors responsible for global warming. Experts agree that one promising approach for the reduction of the CO₂ amount entering the atmosphere is the storage of CO₂ deep underground. A test site is available at Ketzin, Germany, for the study of the sequestration process, its dynamics and the temporal and spatial distribution of CO₂. Carbon dioxide is injected into a saline aquifer at a depth of 800 m, whereas two observation boreholes allow the monitoring of the storage process. Therefore, sensors are needed which are able to monitor the concentration of the dissolved CO₂ in water on-line and in situ. Evanescent-field-spectroscopy is an advantageous spectroscopic technique for detection and analysis of species in places difficult to access and in corrosive, absorbing or highly scattering media. Compared to other spectroscopic methods, which require open optical paths, this sensing method can be attained in an all fiber coupled sensor by using optical fibers as sensing elements as well as for guiding the light to and from the sensor. The sensing region can be inserted into fluids, therefore enabling the real-time determination of the CO₂ content in water. The experimental setup and the sensitivity of the evanescent-field-sensor will be presented.