Photoacoustic CO2 sensor based on a DFB diode laser at 2.7 μm M. Wolff, M. Germer, H. G. Groninga and H. Harde Eur. Phys. J. Special Topics, 153 (2008) 409-413 Published online: 12 March 2008 DOI: 10.1140/epjst/e2008-00473-9