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  1. Article ; Online: Spectroscopic study of N2(b1Πu, ν = 8) by atmospheric-pressure resonant-enhanced multiphoton ionization and fluorescence detection.

    Adams, Steven F / Williamson, James M

    The journal of physical chemistry. A

    2013  Volume 117, Issue 50, Page(s) 13535–13542

    Abstract: A spectroscopic analysis of the strongly perturbed N2(b(1)Πu, ν = 8) state has been conducted, accounting for b(1)Πu(ν = 8) ← X (1)Σg(+)(ν = 0) transitions, for the first time, up to J' = 20. A novel laser spectroscopy technique, using a combination of ... ...

    Abstract A spectroscopic analysis of the strongly perturbed N2(b(1)Πu, ν = 8) state has been conducted, accounting for b(1)Πu(ν = 8) ← X (1)Σg(+)(ν = 0) transitions, for the first time, up to J' = 20. A novel laser spectroscopy technique, using a combination of resonant-enhanced multiphoton ionization and fluorescence detection at atmospheric pressure, avoids the severe effects of perturbation reported in past extreme vacuum ultraviolet absorption experiments that produced weak and unusable spectra for the ν = 8 level. The R, Q, and P branches of the three-photon absorption transition b(1)Πu(ν = 8) ← X(1)Σg(+)(ν = 0) were fit, allowing rotational term energy assignment up to J' = 20 and molecular constants to be determined. Evidence of the previously suspected perturbation in b(1)Πu(ν = 8) is clear in this data, with significant Λ-type doubling at higher J' along with an anomalous negative value determined for the centrifugal distortion coefficient.
    Language English
    Publishing date 2013-12-19
    Publishing country United States
    Document type Journal Article
    ISSN 1520-5215
    ISSN (online) 1520-5215
    DOI 10.1021/jp407412t
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Oxygen rotational temperature determination using empirical analyses of C(3)Π(v' = 2) ← X(3)Σ(v'' = 0) transitions.

    Adams, Steven F / Wu, Yue / Zhang, Zhili

    Applied spectroscopy

    2015  Volume 69, Issue 9, Page(s) 1036–1041

    Abstract: The spectra of molecular oxygen through C(3)Π(v' = 2) ← X(3)Σ(v'' = 0) transitions have been obtained by coherent microwave Rayleigh scattering (radar) from resonance-enhanced multiphoton ionization (REMPI). Measurements of rotational temperatures of ... ...

    Abstract The spectra of molecular oxygen through C(3)Π(v' = 2) ← X(3)Σ(v'' = 0) transitions have been obtained by coherent microwave Rayleigh scattering (radar) from resonance-enhanced multiphoton ionization (REMPI). Measurements of rotational temperatures of molecular oxygen have been demonstrated based on the empirical analyses of the O2 spectra without the requirement of highly resolved rotational features. Three methods, including (1) linewidth fitting, (2) linear fitting, and (3) area fitting have been investigated for temperature measurements within pure oxygen, ambient air, and H2-air and CH4-air flame environments. The first two methods were applied in a moderately low temperature environment with measurement uncertainties less than 11% and 26%, respectively. The area fitting method covered a wider temperature range, from room temperature (~300 K) to flame temperature (~1700 K), with minimal dependence on the fine structures of the O2 spectra. Less elaborate than Boltzmann plot analyses of ultrafine rotational lines from congested upper rotational energy levels in O2(C(3)Π(v' = 2)), these empirical analyses are predictably sensitive to the thermal distribution of molecular oxygen and have been successfully demonstrated as simple and quick methods for remote gas-phase temperature measurement.
    Language English
    Publishing date 2015-09
    Publishing country United States
    Document type Journal Article
    ISSN 1943-3530
    ISSN (online) 1943-3530
    DOI 10.1366/14-07772
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Reduction of breakdown threshold by metal nanoparticle seeding in a DC microdischarge.

    Sawyer, Jordan / Abboud, Jacques / Zhang, Zhili / Adams, Steven F

    Nanoscale research letters

    2015  Volume 10, Page(s) 15

    Abstract: Significant reduction of the breakdown threshold in a DC microdischarge via seeding metal nanoparticles has been demonstrated. Compared to standard Paschen curves in dry air, reductions in the breakdown voltage of 5% to 25% were obtained for PD values ( ... ...

    Abstract Significant reduction of the breakdown threshold in a DC microdischarge via seeding metal nanoparticles has been demonstrated. Compared to standard Paschen curves in dry air, reductions in the breakdown voltage of 5% to 25% were obtained for PD values (the product of pressure and electrode gap distance) ranging from 20 to 40 Torr-cm by seeding aluminum and iron nanoparticles with mean sizes of 75 nm and 80 nm, respectively. No secondary energy source was required to achieve this breakdown threshold reduction. From high-speed chemiluminescence imaging of the discharge evolution, breakdown was shown to be initiated at reduced voltages. Following breakdown, the increase in temperature ignited some of the nanoparticles near the cathode. Results suggest that possible charging of the nanoparticles within the gap may reduce the effective transient distance, leading to the threshold reduction.
    Language English
    Publishing date 2015-01-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2253244-4
    ISSN 1556-276X ; 1931-7573
    ISSN (online) 1556-276X
    ISSN 1931-7573
    DOI 10.1186/s11671-014-0709-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Flame temperature measurements by radar resonance-enhanced multiphoton ionization of molecular oxygen.

    Wu, Yue / Sawyer, Jordan / Zhang, Zhili / Adams, Steven F

    Applied optics

    2012  Volume 51, Issue 28, Page(s) 6864–6869

    Abstract: Here we report nonintrusive local rotational temperature measurements of molecular oxygen, based on coherent microwave scattering (radar) from resonance-enhanced multiphoton ionization (REMPI) in room air and hydrogen/air flames. Analyses of the ... ...

    Abstract Here we report nonintrusive local rotational temperature measurements of molecular oxygen, based on coherent microwave scattering (radar) from resonance-enhanced multiphoton ionization (REMPI) in room air and hydrogen/air flames. Analyses of the rotational line strengths of the two-photon molecular oxygen C(3)Π(v=2)←X(3)Σ(v'=0) transition have been used to determine the hyperfine rotational state distribution of the ground X(3)Σ(v'=0) state. Rotationally resolved 2+1 REMPI spectra of the molecular oxygen C(3)Π(v=2)←X(3)Σ(v'=0) transition at different temperatures were obtained experimentally by radar REMPI. Rotational temperatures have been determined from the resulting Boltzmann plots. The measurements in general had an accuracy of ~±60 K in the hydrogen/air flames at various equivalence ratios. Discussions about the decreased accuracy for the temperature measurement at elevated temperatures have been presented.
    MeSH term(s) Algorithms ; Fires ; Ions/analysis ; Microwaves ; Oxygen/analysis ; Photons ; Radar ; Scattering, Radiation ; Spectrum Analysis/methods ; Temperature ; Thermodynamics ; Thermometry/instrumentation ; Vibration
    Chemical Substances Ions ; Oxygen (S88TT14065)
    Language English
    Publishing date 2012-10-01
    Publishing country United States
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1539-4522
    ISSN (online) 1539-4522
    DOI 10.1364/AO.51.006864
    Database MEDical Literature Analysis and Retrieval System OnLINE

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