Sensitive analytical gas spectroscopy based on free-electron laser and multistage tunable Fabry-Perot interferometer

Summary form only given. New method of sensitive analytical gas spectroscopy based on terahertz free-electron laser (THz NovoFEL) and multistage tunable mesh Fabry-Perot interferometers (MST-FPI) is proposed. In the method a molecule is identified by a spectral position of its individual separate narrow absorption lines. Required tunable narrow laser line can be produced by THz NovoFEL and MST-FPI in spectral range of 90-240 μm (1.2-3.3 THz). Balanced lock-in detection of the line absorption increases sensitivity of the method.