Abstract
We demonstrate an intracavity absorption spectroscopy system based on a broadband single-crystal pulsed Fe:ZnSe laser. The laser operates at room-temperature and is continuously tunable in the spectral range of 3.76-5.29 µm. The long-wavelength emission up to 5.29 µm is a record achievement for Fe:ZnSe lasers, to the best of our knowledge. The developed laser system is applied for measurements of gaseous absorption inside the laser resonator. We demonstrate sensitive detection of (i) CO2 isotopes in the atmosphere and in human breath, (ii) CO in breath (after cigarette smoking) and in the smoke of a smoldering paper, and (iii) N2O in a gas flow. The achieved detection limits are: 0.1 ppm for 12CO2 and 13CO2, 3 ppm for CO, and 1 ppm for N2O. The sensitivity of the current system is primarily limited by the short pump-pulse duration of 40 ns. Possibilities for sensitivity enhancement by up to a factor of 107 are discussed.
Highlights
The mid-infrared (MIR) spectral range currently attracts a growing attention due its high potential for numerous applications
We demonstrate an intracavity absorption spectroscopy system based on a broadband single-crystal pulsed Fe:ZnSe laser
In this work we report a broadband roomtemperature (RT) pulsed Fe:ZnSe laser tailored for highly-sensitive spectroscopic applications using the intracavity absorption spectroscopy (ICAS) technique [1], sometimes called intracavity laser spectroscopy (ICLS), or intracavity laser absorption spectroscopy (ICLAS)
Summary
The mid-infrared (MIR) spectral range currently attracts a growing attention due its high potential for numerous applications. ICAS was employed in a wide range of hostile environments, including simultaneous concentration measurements of various molecular species in flames [4,5], identification and specification of chemical reactions in flames [6,7], simultaneous determination of temperature, pressure, and concentrations of gaseous samples in shock-tubes [8], measurements of absorption cross-sections of gas-phase FeO in a shock tube [9], monitoring of single transient processes in plasmas with microsecond time resolution [10], as well as simultaneous analysis of several isotopes of CO2 in human breath [11] Despite these promising results achieved with ICAS in the visible and near-infrared in the recent years, there is still a great but largely unused potential for significant progress in this field, namely the advancement into the MIR spectral range, where the fundamental vibrational transitions of many species are located [12]. Highly-sensitive ICAS measurements of several of these species are demonstrated in this work
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