signature=62974444db9a7a29c7b622b84389c12c,Photoacoustic sensor for short-chained hydrocarbon isotop...

摘要：

The measurement of short-chained hydrocarbon concentrations and their isotopic composition is essential to many applications from environmental research to natural gas exploration. For instance, the isotopic signature of methane (13CH4 : 12CH4) allows tracing the gas back to its ecological or anthropogenic source and can help constrain atmospheric models [1]. Concerning natural gas exploration, the 13C-isotope ratio of hydrocarbons provides information about the gas type (i.e. bacterial, thermogenic or mixed) and its maturity [2]. In addition, observed "isotopic reversal" in shale gas can be an indication of a high-production well [3]. Measurements of methane at natural isotopic abundance have been previously performed with high resolution [4]. We report, to our knowledge, first time photoacoustic measurements of methane (13CH4), ethane (13C12CH6, 13C2H6) and propane isotopologues (13C12C2H8) using two distributed feedback interband cascade lasers (DFB ICLs). The lasers operate in continuous mode at room temperature in the spectral regions around 3333 nm and 3380 nm, respectively. They feature a spectral linewidth below 10 MHz allowing ultra-high resolution of characteristic absorption features. [1] Rigby M, Manning AJ, Prinn RG, J. Geophys. Res., 117, D12312 (2012). [2] Ellis L, Brown A, Schoell M, Uchytil S, Oil Gas J., 101 (21), 32-41 (2003). [3] Zumberge J, Ferworn K, Brown S, Mar. Petrol. Geol., 31 (1), 43-52 (2012). [4] Wolff M, Rhein S, Bruhns H, Nhle L, Fischer M, Koeth J, Sens. Actuator B Chem., 187, 574-577 (2013).

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