Cavity enhanced plasma self-absorption spectroscopy

Walsh, Anton J.; Linnartz, H.

doi:10.1063/1.4748125

Cited by 5 publications

(6 citation statements)

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“…These weak features are due to self-absorption of light emitted by the plasma, enhanced by the optical cavity. The underlying process, cavity-enhanced plasma self-absorption spectroscopy (CEp-SAS), has been described in detail in ref 79. The plasma background removed transmission of light through the cavity while the plasma is running, I−BG plasma , is shown in Figure 4.…”

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confidence: 99%

Optomechanical Shutter Modulated Broad-Band Cavity–Enhanced Absorption Spectroscopy of Molecular Transients of Astrophysical Interest

et al. 2013

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We describe a sensitive spectroscopic instrument capable of measuring broad-band absorption spectra through supersonically expanding planar plasma pulses. The instrument utilizes incoherent broad-band cavityenhanced absorption spectroscopy (IBBCEAS) and incorporates an optomechanical shutter to modulate light from a continuous incoherent light source, enabling measurements of durations as low as ∼400 μs. The plasma expansion is used to mimic conditions in translucent interstellar clouds. The new setup is particularly applicable to test proposed carriers of the diffuse interstellar bands, as it permits swift measurements over a broad spectral range with a resolution comparable to astronomical observations. The sensitivity is estimated to be better than 10 ppm/pass, measured with an effective exposure time of only 1 s.

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Section: Resultsmentioning

confidence: 99%

Optomechanical Shutter Modulated Broad-Band Cavity–Enhanced Absorption Spectroscopy of Molecular Transients of Astrophysical Interest

et al. 2013

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“…The potential of CESAS is demonstrated on the example of an in situ detection of low concentration transients in expanding plasma in real time. 5 In regular CES-based methods, an absorption sample is placed inside an optical cavity formed by two high reflectivity (HR) mirrors, commonly with R > 99.99%, that are mounted on high precision alignment tools. Light from an external light source, such as a dye laser, super continuum laser, or Xe-arc lamp, is incident on the front mirror of the cavity.…”

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confidence: 99%

“…More details on the derivation of this formula are available from Ref. 5. The method works both for pulsed and continuous light sources as signal is only recorded when light is actually emitted, concurrent with the absorbing species.…”

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Note: Cavity enhanced self-absorption spectroscopy: A new diagnostic tool for light emitting matter

Walsh

Zhao

Linnartz

2013

Review of Scientific Instruments

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We introduce the concept of Cavity Enhanced Self-Absorption Spectroscopy (CESAS), a new sensitive diagnostic tool for analyzing light-emitting samples. The technique works without an additional light source and its implementation is straight forward. In CESAS, a sample (plasma, flame, or combustion source) is located in an optically stable cavity consisting of two high reflectivity mirrors, and here it acts both as light source and absorbing medium. A modest portion of the emitted light is trapped inside the cavity, making 10(4)-10(5) cavity round trips while crossing the sample and an artificial augmentation of the path length of the absorbing medium occurs as the light transverses the cavity. Light leaking out of the cavity simultaneously provides emission and absorption features. The performance is illustrated by CESAS results on supersonically expanding pulsed hydrocarbon plasma. We expect CESAS to become a generally applicable analytical tool for real time and in situ diagnostics.

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“…The large majority of studies carried out with linear (two-) mirror cavities focus on 39 the detection of gas phase species (see section 4), mostly employing setups where the cavity 40 is enclosed by a flow [38][39][40] or static cells [8,41,48] at high or modest pressures, or by vac-41 uum chamber for low pressure regime [37,45,75]. In some atmospheric applications open-42 path configurations were also used ( Figure 3.1(a.i)), e.g.…”

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confidence: 99%