The Jungfraujoch hosts a new laser system to discern the level ofhuman activity on greenhouse gasses.

Caption: Measuring chamber: The gas sample to be evaluated is introduced continuously (up to 10 liters/minute) and is measured through the absorption of the laser beam (visible in red on this image).

The experiment, conducted at high altitude, allows for the first time the continuous measurement of the isotopic signature of CO₂ characteristic of the main sources of carbon dioxide. This continuous ‘stream measurement’ is now possible because of a newly developed quantum cascade laser, which was developed by the Neuchâteloise company Alpes Lasers, a partner in the National Centre of Competence in Research – Quantum Photonics (NCCR-QP).

Transportable apparatus allows for continuous ‘real-time’ measurement:
Empa has created a robust and transportable apparatus to house this laser, which allows for continuous measurement on site with results automatically read and processed remotely in ‘real time’. "We can evaluate our measurements made at Jungfraujoch at anytime from our laboratory situated in Zurich," said Lukas Emmenegger, a researcher at Empa. "The research we conduct will be useful to climatologists and researchers worldwide, who until now have had to rely on limited individual samples and tedious laboratory analysis. The continuous measurement of all major CO₂ isotopes measurement was not possible before this new measurement technology was developed."

Assembly and adjustment of the optical system.

Jungfrau unique:
As for choosing the Jungfrau as the field location for this dexterous invention, Emmenegger states that there were two advantages: first, measurements at high altitude reflect the anthropogenic or biogenic activity on a large scale because the air mass being measured has traveled across the continent; and second, the Jungfrau already serves as a station for the National Network for Monitoring Air Pollutants (NABEL) and for the Atmospheric Research of the Global Atmosphere Watch (GAW) of the World Meteorological Organization (WMO).

The laser beam must be guided towards the measuring chamber, and then the signal is turned towards the detector.

Discerns isotopic signatures:
Carbon dioxide is the main gas responsible for climate change. As CO₂ is emitted by various sources – both man-made and biogenic (e.g. bacterial, animal and plant respiration) – an accurate understanding of the quantity produced by different sources is essential to developing measures to reduce emissions.

Fortunately, nature provides us with a valuable, although relatively enigmatic tool: the isotopic signature. Depending on its origin, the isotopic composition of CO₂ is slightly altered. Plants and bacteria are able to "filter" certain isotopes of carbon or oxygen in CO₂ during photosynthesis or respiration. This "selection" is also found in oil and other fossil fuels and therefore in the CO₂ produced in burning these fuels. The instrument developed by Lukas Emmenegger’s group of researchers at Empa jointly with a commercial partner in the U.S. (Aerodyne Research), is capable of measuring this minute difference. Since 2007, five units have already been sold by Aerodyne research. The Empa team is also maintaining a close collaboration with Professor Leuenberger of the University of Bern who has been analyzing the isotopic composition of individual samples of CO₂ at Jungfraujoch for several years. The project was supported financially by the National Centre of Competence in Research - Quantum Photonics, Alpes Lasers SA, and the Federal Office of Environment (FOEN).