DFWM spectroscopy as a tool to detect products from low-density discharges and nozzle expansions

Konz, E.; Fabelinsky, V. I.; Marowsky, G.; Rubahn, H.-G.

doi:10.1016/s0009-2614(95)01240-0

Cited by 8 publications

(7 citation statements)

References 15 publications

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“…14. The O concentration increases up to 90 W and saturates beyond. That type of saturation of the discharge efficiency was already observed by several authors [8,46,47].…”

Section: Concentration Measurementssupporting

confidence: 70%

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Atomic oxygen detection using two-photon degenerate four wave mixing

Picard

Grisch

Attal‐Trétout

et al. 1997

Z Phys D - Atoms, Molecules and Clusters

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We report a new application of Forward Degenerate Four Wave Mixing to the two-photon transition 2pP3p of atomic oxygen. This spectroscopy has been used to detect oxygen atoms produced in a microwave discharge. The possibility to determine number densities over a range of microwave plasma parameters is investigated. In contrast to conventional linear techniques, quantitative data are relatively easy to obtain even for environments with high background luminosity, limited optical access and inhomogeneous quenching.

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“…14. The O concentration increases up to 90 W and saturates beyond. That type of saturation of the discharge efficiency was already observed by several authors [8,46,47].…”

Section: Concentration Measurementssupporting

confidence: 70%

“…Using TPDFWM is particularly useful for in-situ detection of atomic species in media in which LIF is difficult to implement. For example, when probe volumes are located close to intense source of radiation such as hot nozzles [47] or near hot substrates like in chemical vapor deposition [48].…”

Section: Resultsmentioning

confidence: 99%

Atomic oxygen detection using two-photon degenerate four wave mixing

Picard

Grisch

Attal‐Trétout

et al. 1997

Z Phys D - Atoms, Molecules and Clusters

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“…It displays the simplicity of single beam operation, excellent discrimination against other interfering species, and high sensitivity, characteristics that have been demonstrated elsewhere as being advantageous for the detection of NO generated in an air-acetylene flame [18], where it is apparent that phase matching is achieved even in extreme environments. Our results compare favorably with detection using degenerate four-wave mixing [1,19] and other resonance enhanced nonlinear techniques. In the case of SPFWM, a greater pump power is required to achieve a comparable sensitivity.…”

Section: (Received 27 May 1997)mentioning

confidence: 55%

Infrared Seeded Parametric Four-Wave Mixing for Sensitive Detection of Molecules

et al. 1997

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We have developed a sensitive resonant four-wave mixing technique based on two-photon parametric four-wave mixing with the addition of a phase matched "seeder" field. Generation of the seeder field via the same four-wave mixing process in a high pressure cell enables automatic phase matching to be achieved in a low pressure sample cell. This arrangement facilitates sensitive detection of complex molecular spectra by simply tuning the pump laser. We demonstrate the technique with the detection of nitric oxide down to concentrations more than 4 orders of magnitude below the capability of parametric four-wave mixing alone, with an estimated detection threshold of 10 12 molecules͞cm 3 . [S0031-9007(97) PACS numbers: 42.65. Ky, 33.20.Lg, 39.30. + w Trace species detection using electronic transitions in the visible and ultraviolet is advantageous due to the strong resonance enhancement of the interaction cross section. Detection of molecules in the ultraviolet can be achieved with many different techniques, the suitability of which is application dependent. Pulsed lasers offer a great deal of versatility, providing broad tunability over the visible and ultraviolet as well as high spectral intensities suitable for nonlinear techniques. Resonance enhanced degenerate four-wave mixing is one such technique which has received much attention due to its high sensitivity and highly collimated coherent signal output [1]. Coherent techniques are particularly applicable to remote sensing applications where there are restrictions to optical access. Currently all nonlinear diagnostic techniques that generate a coherent signal beam require the use of multiple beams satisfying complicated phase matching geometries, and many are susceptible to spectral interference from other molecular species.In this Letter we demonstrate a new resonance enhanced nonlinear technique useful for detecting molecular species in trace amounts, which only requires a single beam, is automatically phase matched, and provides excellent species discrimination. The technique, named seeded parametric four-wave mixing (SPFWM), is based on two-photon resonant parametric four-wave mixing (PFWM) [2,3], with the addition of an extra "seeder" field. Both techniques generate coherent signals at wavelengths different from that of the pump, uniquely determined by the interacting species (see Fig. 1) and which travel collinearly with the pump beam. The addition of a phase matched seeder field to the PFWM process serves to increase the sensitivity by many orders of magnitude. The seeder field is simply provided by PFWM in a high gain (high pressure) cell containing the molecule of interest; the signal fields travel collinearly with the pump, and the unwanted component is removed using a filter. Therefore, SPFWM will automatically provide a phase matched seeder field over the entire extent of a molecular spectrum and so is suitable for use with tunable pulsed dye lasers for detecting complex molecular spectra. We demonstrate the potential of SPFWM using a recently rep...

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“…1,2 Both techniques have been used with great success in probing absorptions of dissociative or transient species and decay dynamics of excited molecular states. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Being absorption based coherent nonlinear processes, DFWM and TC-LIG have numerous advantages over other spectroscopic techniques. For example, coherence in the signal beam offers theoretically background free detection for a judiciously designed optical arrangement.…”

Section: Introductionmentioning

confidence: 99%

Degenerate four wave mixing of pyridazine from a slit nozzle

Kong

1998

The Journal of Chemical Physics

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Polarization and probe delay effect on degenerate four wave mixing of pyrazine Using a pulsed supersonic slit nozzle, the nonfluorescing *←n transition of pyridazine was investigated. The degenerate four wave mixing ͑DFWM͒ spectra showed numerous vibrational bands over a 1200 cm Ϫ1 region. Most of these bands were parallel transitions with a strong Q branch and weaker but observable P and R branches. Based on our previous model ͓H. Li and W. Kong, J. Chem. Phys. 107, 3774 ͑1997͔͒, these transitions were simulated with success. The polarization dependence of the rotational branching ratios suggested that primary contributions to the DFWM signal were from large spaced gratings formed by ground state molecules. The lack of contributions from excited state gratings and small spaced gratings was attributed to the fast internal conversion process on the S 1 surface of pyridazine ͑0.3-3 ns͒, the wash-out time due to movements of the sample in a molecular beam, and the duration time of the excitation laser ͑7 ns͒. Two vibrational bands showed unexpected enhancement in the P or R branch, but for each band, one adjustment factor was sufficient to reproduce the spectra recorded under all different polarization combinations. Perturbations were observable from the rotationally resolved spectra, however in most cases, rotational progressions did not seem to be affected by the perturbation in terms of both line positions and intensities. A more detailed analysis of the supersonically cooled spectra, together with data from a room temperature gas cell and ab initio calculations, will be necessary to completely interpret the spectroscopy of pyridazine. This paper demonstrates that with the increased sensitivity achievable through a slit nozzle, DFWM is an effective technique for detailed spectroscopic studies, particularly for nonfluorescing species.

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DFWM spectroscopy as a tool to detect products from low-density discharges and nozzle expansions

Cited by 8 publications

References 15 publications

Atomic oxygen detection using two-photon degenerate four wave mixing

Atomic oxygen detection using two-photon degenerate four wave mixing

Infrared Seeded Parametric Four-Wave Mixing for Sensitive Detection of Molecules

Degenerate four wave mixing of pyridazine from a slit nozzle

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