Ultra-broadband mid-infrared supercontinuum-based spectroscopy for greenhouse gas monitoring at wastewater treatment plants

• DOI: 10.5194/egusphere-egu24-8526
• Publication Date: 2024-03-08T18:18:58Z
• Authors: Roderik Krebbers; Kees van Kempen; Yueyu Lin; Amir Khodabakhsh; Simona Cristescu
• Keywords: Supercontinuum

Ultra-broadband spectroscopy in the mid-infrared (MIR) wavelength range, where most molecular species have strong, distinct absorption features, has a great potential for gas sensing applications. Novel MIR supercontinuum (SC) sources excel their ability to provide broadband light together with high spatial coherence. Using this unique combination of properties, we recently demonstrated SC tailor-made Fourier Transform Spectrometer (FTS) and multipass cell multispecies trace detection [1]. Moreover, novel application is utilize coherence source monitor outdoor (greenhouse) concentrations through free space. In open-path spectroscopy, beam guided over an (outdoor) path, instead sampling cell. The gases interest are integrated which useful detecting greenhouse area or around emission source. Wastewater treatment plants known emissions CO2, CH4, N2O. However, little about fluctuation rates these time relation internal external factors. We developed new, transportable instrument comprises unique, ultra-broad spectrum from 2 – 11.5 µm ~3 W output power custom-built transform spectrometer [2]. sent open path cubic retroreflector, it reflected back FTS. beam, extensive, optical paths can be achieved, while broad enables simultaneous many different species. present results field measurements at wastewater plant monitored concentration (CH4, N2O, CO2) other (e.g., NH3 CO) simultaneously atmosphere surrounding aerobic tank (Figure 1).  will shed on perspective instrumentation monitoring emitting sources, as providing reliable data modelling studies dynamics sources. Figure 1: Satellite image (in red). Left insert: Retrieved methane using black) validation red, measured point marked “x” photo). Right Close-up instrument.   [1] M. A. Abbas, K. E. Jahromi, Nematollahi, R. Krebbers, N. Liu, G. Woyessa, O. Bang, L. Huot, F. J. Harren, Khodabakhsh, "Fourier based high-repetition-rate detection," Opt. Express 29, 22315-22330 (2021). [2] van Kempen, S. Vasilyev, I. Peterse, Lücker, Cristescu, “Ultra-broadband 2–11.5 IDFG-based source”, Optica Open. Preprint. DOI:10.1364/opticaopen.24967692.v1.