Conjugating precision and acquisition time in a Doppler broadening regime by interleaved frequency-agile rapid-scanning cavity ring-down spectroscopy.
J Chem Phys
; 147(13): 134201, 2017 Oct 07.
Article
em En
| MEDLINE
| ID: mdl-28987101
ABSTRACT
We propose a novel approach to cavity-ring-down-spectroscopy (CRDS) in which spectra acquired with a frequency-agile rapid-scanning (FARS) scheme, i.e., with a laser sideband stepped across the modes of a high-finesse cavity, are interleaved with one another by a sub-millisecond readjustment of the cavity length. This brings to time acquisitions below 20 s for few-GHz-wide spectra composed of a very high number of spectral points, typically 3200. Thanks to the signal-to-noise ratio easily in excess of 10 000, each FARS-CRDS spectrum is shown to be sufficient to determine the line-centre frequency of a Doppler broadened line with a precision of 2 parts over 1011, thus very close to that of sub-Doppler regimes and in a few-seconds time scale. The referencing of the probe laser to a frequency comb provides absolute accuracy and long-term reproducibility to the spectrometer and makes it a powerful tool for precision spectroscopy and line-shape analysis. The experimental approach is discussed in detail together with experimental precision and accuracy tests on the (30 012) â (00 001) P12e line of CO2 at â¼1.57 µm.
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MEDLINE
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En
Ano de publicação:
2017
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Article