Stimulated Raman scattering measurements of V–V transfer in oxygen

Ahn, Tai; Adamovich, Igor V.; Lempert, Walter R.

doi:10.1016/j.chemphys.2005.10.036

Cited by 26 publications

(12 citation statements)

References 25 publications

(63 reference statements)

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“…As expected, O 2 vibrational level populations exceeded those of CO and N 2 (see figure 31). These experimental results are In a related work [90][91][92], stimulated Raman scattering, such as…”

Section: Spontaneous Raman Scattering: Vibrational Populations and Tementioning

confidence: 85%

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

Lempert

Adamovich

2014

J. Phys. D: Appl. Phys.

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The paper provides an overview of the use of coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman scattering for diagnostics of low-temperature nonequilibrium plasmas and nonequilibrium high-enthalpy flows. A brief review of the theoretical background of CARS, four-wave mixing and Raman scattering, as well as a discussion of experimental techniques and data reduction, are included. The experimental results reviewed include measurements of vibrational level populations, rotational/translational temperature, electric fields in a quasi-steady-state and transient molecular plasmas and afterglow, in nonequilibrium expansion flows, and behind strong shock waves. Insight into the kinetics of vibrational energy transfer, energy thermalization mechanisms and dynamics of the pulse discharge development, provided by these experiments, is discussed. Availability of short pulse duration, high peak power lasers, as well as broadband dye lasers, makes possible the use of these diagnostics at relatively low pressures, potentially with a sub-nanosecond time resolution, as well as obtaining single laser shot, high signal-to-noise spectra at higher pressures. Possibilities for the development of single-shot 2D CARS imaging and spectroscopy, using picosecond and femtosecond lasers, as well as novel phase matching and detection techniques, are discussed. 45 I 2

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Section: Spontaneous Raman Scattering: Vibrational Populations and Tementioning

confidence: 85%

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

Lempert

Adamovich

2014

J. Phys. D: Appl. Phys.

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“…The observation of this Q branch suggested that it should be possible to use this very the same scheme in other molecules to access and study excited vibrational states different from the ones initially populated by optical pumping. Raman spectra of transitions from states populated by collisions have been previously observed in several molecules including 14 N 2 itself , but high sample pressures are typically a requirement in these experiments, leading to the observation of Q branches in which the rotational structure cannot be resolved. However, as our results in 14 N 2 prove, the observation of fully resolved Q branches in light molecules should be possible with our setup if a suitable choice of sample pressure and pump‐probe delay is made.…”

Section: Introductionmentioning

confidence: 99%

High resolution stimulated Raman spectroscopy from collisionally populated states after optical pumping: the 3ν₂←2ν₂and ν₂+2ν₄+ν₅←2ν₄+ν₅ Qbranches of¹²C₂H₂and the 3ν₂←2ν₂ Qbranch of¹²C₂D₂.

Martínez

Bermejo

Lonardo

et al. 2016

J. Raman Spectrosc.

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In this work, we demonstrate the combined use of a pump‐probe Raman–Raman technique and the naturally occurring process of vibration‐to‐vibration (V–V) collisional relaxation to populate and obtain high‐resolution Raman spectra of vibrationally excited states that cannot be easily accessed by other means. First, a stimulated Raman pump stage is used to promote population to a vi = 1 excited state. This is followed by a time interval whose length is chosen so that, at the working pressure, significant V–V collisional energy transfer takes place and the quanta of vibrational excitation initially placed in vi = 1 naturally reach other excited states. Finally, after this delay, the probe stage is used to obtain high‐resolution Raman spectra of hot bands departing from these collisionally populated states. The technique has been demonstrated on two isotopologues of acetylene, 12C2H2 and 12C2D2, and has allowed the observation of transitions departing from the 2ν2 ( Σg+) and 2ν4 + ν5 (IΠu) collisionally populated states. Accurate values of the spectroscopic parameters for the v2 = 3 vibrationally excited states for both isotopologues were obtained, for the first time, from the least‐squares analysis of the assigned transitions. In addition, the observation of Q branch lines of v2 = 1, v4 = 2, v5 = 1 (IΠu) ← v4 = 2, v5 = 1 (IΠu) band for 12C2H2 allowed the spectroscopic characterization of the upper state. Copyright © 2016 John Wiley & Sons, Ltd.

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“…However, due to the low pulse energy of the pico-second laser this was found to not be necessary. In addition previous studies have [19][20][21][22] seeded the Raman cell at the first Stokes frequency, Raman pumping cell is not seeded. It was, however, heated in an attempt to induce conductive cooling, but had little effect in the conversion efficiency.…”

Section: Stokes Generationmentioning

confidence: 99%

Simplification of RELIEF Velocimetry Using Picosecond Tagging and Broad Band Interrogation

Webster

Lempert

2008

46th AIAA Aerospace Sciences Meeting and Exhibit

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This work demonstrates the potential for a simplified portable "RELIEF" velocity apparatus, employing the use of a compact, relatively low cost, ~150 pico-second duration Nd:YAG laser to vibrationally excite molecular oxygen in a stimulated Raman scattering, tagging step. The tagged oxygen molecules are interrogated by Laser Induced Fluorescence, utilizing a low cost broadband ArF laser, as a replacement for the injection-seeded ArF laser which has been traditionally employed. The Stokes beam required in the tagging step is generated in both a single and multi-pass Raman Shifting Cell, with the corresponding Raman shift conversion efficiencies reported herein.

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Stimulated Raman scattering measurements of V–V transfer in oxygen

Cited by 26 publications

References 25 publications

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

High resolution stimulated Raman spectroscopy from collisionally populated states after optical pumping: the 3ν₂←2ν₂and ν₂+2ν₄+ν₅←2ν₄+ν₅ Qbranches of¹²C₂H₂and the 3ν₂←2ν₂ Qbranch of¹²C₂D₂.

Simplification of RELIEF Velocimetry Using Picosecond Tagging and Broad Band Interrogation

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Stimulated Raman scattering measurements of V–V transfer in oxygen

Cited by 26 publications

References 25 publications

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

High resolution stimulated Raman spectroscopy from collisionally populated states after optical pumping: the 3ν2←2ν2and ν2+2ν4+ν5←2ν4+ν5 Qbranches of12C2H2and the 3ν2←2ν2 Qbranch of12C2D2.

Simplification of RELIEF Velocimetry Using Picosecond Tagging and Broad Band Interrogation

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High resolution stimulated Raman spectroscopy from collisionally populated states after optical pumping: the 3ν₂←2ν₂and ν₂+2ν₄+ν₅←2ν₄+ν₅ Qbranches of¹²C₂H₂and the 3ν₂←2ν₂ Qbranch of¹²C₂D₂.