Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/15175
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- Title
- Detection of trace gases by rapidly-swept continuous-wave cavity ringdown spectroscopy : pushing the limits of sensitivity
- Related
- Applied physics B : lasers and optics, Vol. 85, Issue 2-3, p.355-364
- DOI
- 10.1007/s00340-006-2371-2
- Publisher
- Springer Verlag
- Date
- 2006
- Author/Creator
- He, Y
- Author/Creator
- Orr, B. J
- Description
- Cavity ringdown (CRD) absorption spectroscopy enables spectroscopic sensing of gases with a high sensitivity and accuracy. Instrumental improvements result in a new highperformance continuous-wave (cw) CRD spectrometer using a rapidly-swept cavity of simple design. It employs efficient data-acquisition procedures, high-reflectivity mirrors, a low adsorption flow cell, and various compact fibre-optical components in a single-ended transmitter-receiver configuration suitable for remote sensing. Baseline noise levels in our latest cw-CRD experiments yield a competitive noise-equivalent absorption limit of ~ 5×10⁻¹⁰ cm⁻¹Hz⁻¹/², independent of whatever molecules are to be detected. Measurements in the near-infrared wavelength range of 1.51–1.56 μm yield subppmv (i.e., ppbv or better) sensitivity in the gas phase for several representative molecules (notably CO₂, CO, H₂O, NH₃, C₂H₂, and other hydrocarbons). By measuring spectroscopic features in the 1.525 μm band of C₂H₂ gas, we realise detection limits of 19 nTorr (2.5×10⁻¹¹ atm) of neat C₂H₂ (Doppler-limited at low pressure) and 0.37 ppbv of C₂H₂ in air (pressure-broadened at 1 atm). Our cw-CRD spectrometer is a high-performance sensor in a relatively simple, low-cost, compact instrument that is amenable to chemical analysis of trace gases in medicine, agriculture, industry, and the environment.
- Description
- 10 page(s)
- Subject Keyword
- remote sensing
- Subject Keyword
- trace gases
- Subject Keyword
- spectrum analysis
- Subject Keyword
- absorption spectra
- Subject Keyword
- analytic chemistry
- Resource Type
- journal article
- Organisation
- Macquarie University. Dept. of Physics
- Organisation
- Macquarie University. Centre for Lasers and Applications
- Identifier
- http://hdl.handle.net/1959.14/15175
- Identifier
- ISSN:1432-0649
- Identifier
- mq-rm-2006005517
- Language
- eng
- Reviewed
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