Cavity Ring‐Down Spectroscopy of Molecular Transients of Astrophysical Interest

Linnartz, H.

doi:10.1002/9781444308259.ch6

Cited by 8 publications

(2 citation statements)

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“…These are recorded in emission through a supersonically expanding plasma. Such plasma expansions have become a standard to generate molecular transients of astrophysical interest and their applications in astronomy have been reviewed recently by Linnartz (2009). The overall aim of this experimental study is to identify possible carriers of the narrow emission features as observed around the Red Rectangle and simultaneously to follow the chemical evolution in the outflows of this proto-planetary nebula.…”

Section: Introductionmentioning

confidence: 99%

C₂emission features in the Red Rectangle

Wehres

Romanzin

Linnartz

et al. 2010

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Context. The Red Rectangle proto-planetary nebula (HD 44179) is known for a number of rather narrow emission features superimposed on a broad extended red emission (ERE) covering the 5000-7500 Å regime. The origin of these emission features is unknown. Aims. The aim of the present work is to search for potential carriers by combining new observational and laboratory data. This also allows to interpret spectral emission features in terms of actual physical conditions like temperature and density constraints and to trace chemical processes in the outflows of the Red Rectangle. Methods. Observational spectra have been obtained with the EMMI-NTT at offsets of 3 , 6 , 7 , 11 , 16 and 20 distance to the central star HD 44179. The spectra are compared to the outcome of a time-gated laser induced fluorescence laboratory study of an expanding acetylene plasma using a special supersonic pin-hole discharge source. With this set-up the hydrocarbon chemistry in the Red Rectangle nebula is simulated under laboratory controlled conditions. The plasma source has the unique feature to generate electronically and vibrationally excited species at low rotational temperatures. The comparison is facilitated by a simple model for fluorescent emission in the nebula. Results. Two of the astronomically observed narrow emission bands can be assigned as originating from unresolved rovibronic progressions within the d 3 Π g → a 3 Π u Swan system of the C 2 radical. The band appearance corresponds to a rotational temperature between 200 and 1000 K. The emission is driven by absorption in the C 2 Phillips bands followed by intersystem crossing from the singlet to the triplet state and pumping in the Swan bands. Conclusions. These observations imply an active (photo)chemistry in the ejecta of the Red Rectangle.

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Section: Introductionmentioning

confidence: 99%

C₂emission features in the Red Rectangle

Wehres

Romanzin

Linnartz

et al. 2010

A&A

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“…High-pressure pulsed planar plasma expansions, have proved to be very successful in producing large abundances of highly reactive molecular transients, such as carbon chain radicals 65,66 and polycyclic aromatic hydrocarbon cations (PAHs). 40,41,67 Slit pulsed discharge nozzles offer an extension to discharge cells, largely pioneered by Oka et al, 68,69 as low rotational temperatures (∼15 K) can be realized in a generally Doppler free environment.…”

Section: Introductionmentioning

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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