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  • 1
    Electronic Resource
    Electronic Resource
    Measurements of rotational energy transfer and quenching in OHA 2 σ +,υ′ = 0 at elevated temperature (1994)
    Springer
    Applied physics 58 (1994), S. 447-457 
    Details
    ISSN: 1432-0649
    Keywords: 34.00
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Total rotational energy transfer rates have been measured at 1330 K for specific rotational levels in the OHA 2 σ +,υ′ = 0 state in collisions with H2O. Rotational levels ranging fromN′ = 0 to 15 were studied. Measurements were performed in the post-flame region of a stoichiometric H2/O2/He flame operating at 25 mbar. Quenching rates following excitation of individual upper rotational states were also measured. The RET and quenching rates both exhibit monotonic decreases with increasing rotational quantum number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01081075
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  • 2
    Electronic Resource
    Electronic Resource
    State-specific rotational energy transfer in OH (A 2Σ+, v′=0) by some combustion-relevant collision partners (1992)
    Springer
    Applied physics 55 (1992), S. 305-310 
    Details
    ISSN: 1432-0649
    Keywords: 34.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract State-to-state rotational energy transfer (RET) co-efficients were determined for inelastic collisions of OH (A 2Σ+, v′=0) with N2, CO2, and H2O at 300 K. The experimental procedure described previously allows the direct evaluation of state-specific RET coefficients from time-resolved laser-induced fluorescence (LIF) measurements without any assumptions on the RET. The results show strikingly different RET behaviour for the three collision partners. The data can serve as a basis for a comparison with dynamic collision models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333071
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  • 3
    Electronic Resource
    Electronic Resource
    State-to-state rotational energy transfer in OH (A 2Σ+, υ′=1) (1993)
    Springer
    Applied physics 56 (1993), S. 249-258 
    Details
    ISSN: 1432-0649
    Keywords: 34.00
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract State-to-state rotational energy transfer (RET) coefficients for thermal collisions of OH (A 2Σ+, υ′=1) with He, Ar, N2, CO2, and H2O at 300K were determined from time-resolved laser-induced fluorescence (LIF) measurements. The RET coefficients are very similar in both qualitative behaviour and absolute magnitude to those measured previously for OH (A 2Σ+, υ′=0).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325212
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  • 4
    Electronic Resource
    Electronic Resource
    Atomic hydrogen concentration profiles at filaments used for chemical vapor deposition of diamond (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 571-573 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The quantitative determination of atomic hydrogen concentrations cH in the vicinity of hot filaments is performed with two-photon laser-induced fluorescence. The measurements yield atomic hydrogen concentration profiles up to 28 mm from the filament surface with a spatial resolution of about 0.5 mm. The nonequilibrium nature of the hydrogen dissociation on the filament surface results in a saturation of hydrogen concentration profiles cH(r) for gas pressures above 10 mbar. Atomic concentrations in immediate vicinity of the filament are significantly lower than expected from thermodynamical calculations and depend on the filament diameter. Addition of methane results in a decrease of cH by more than 30% near the filament and a steeper cH(r) dependence, demonstrating the accelerated consumption of H atoms by the presence of hydrocarbon species. H concentration profiles for Ta, Ir, and W filaments show a dependence on filament materials which might be taken into account when selecting filament materials for chemical vapor deposition of diamond.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104590
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  • 5
    Electronic Resource
    Electronic Resource
    Laser-induced fluorescence determination of flame temperatures in comparison with CARS measurements (1990)
    Springer
    Applied physics 50 (1990), S. 513-518 
    Details
    ISSN: 1432-0649
    Keywords: 82.40Py ; 33.50Dq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Temperature profiles in several premixed low pressure H2/O2/N2 flames and in an atmospheric pressure CH4/air flame were determined by laser-induced fluorescence (LIF) and by CARS experiments. In the LIF study, temperatures were derived from OH excitation spectra, CARS temperatures were deduced from N2 Q-branch spectra. The present study is the first quantitative comparison of these two methods for temperature determination in flames burning at pressures up to 1 bar. The resulting temperatures showed good agreement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408777
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  • 6
    Electronic Resource
    Electronic Resource
    A detailed rate equation model for the simulation of energy transfer in OH laser-induced fluorescence (1996)
    Springer
    Applied physics 62 (1996), S. 583-599 
    Details
    ISSN: 1432-0649
    Keywords: 34.00
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A rate equation model (the LASKIN program packet) has been developed for the detailed computation of energy transfer in Laser-Induced Fluorescence (LIF). Calculations of this type are necessary for analysis of the influence of energy transfer processes [e.g., electronic quenching and Rotational Energy Transfer (RET)] on the fluorescence signal. The model has been utilized to examine linear LIF in the OHA 2Σ+-X 2 Π (0, 0) band. Available data on quenching, RET and spontaneous emission rates for the (A, v′ = 0) state have been reviewed, and models for the state-specific RET and quenching rates have been developed. The accuracy of the calculations has been confirmed by comparison with experimental data, and the LASKIN program has been applied to the analysis of potential error sources in the widely applied two-line LIF temperature-measurement technique. Extensions of the model to the examination of saturated LIF, OHA–X (1, 0) and (3, 0) excitation and LIF of other species (e.g., O2 and NO) are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01081697
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  • 7
    Electronic Resource
    Electronic Resource
    Measurement of vibrational energy transfer of OH (A2Σ+,v′=1→0) in low-pressure flames (1997)
    Springer
    Applied physics 65 (1997), S. 81-91 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 33.50.-j; 34.50.Ez; 82.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: 2 Σ+) was measured in a low-pressure H2/O2 flame for three rotational levels of OH (v′=1). Rate coefficients for collisions with H2O and N2 were determined. At 1600 K, kVET (N2) is (in 10-11 cm3s-1) 10.1±2, 6.1±1.8, and 3.8±1.3 for N′=0, 5, and 13, respectively. The kVET (H2O) is 〈1.1±1.8. The kQ (N2) is 〈2.4±8 for both vibrational levels. The kQ (H2O) in v′=1 is 59.1±6.5, 54.7±6.4, and 54.9±6.6 for N′=0, 5, and 13, respectively, and, determined indirectly, 74.6±10.4, 70.6±10.3, and 63.4±7.3 for N′=0, 5, and 13 in v′=0. A multi-level model of OH population dynamics, which is being developed for the quantitative simulation of experimental LIF spectra, was extended to include VET. It was attempted to simulate state-to-state-specific VET coefficients for N2 collisions. From these simulations it appears that angular momentum conservation does not determine the N dependence of the vibrational relaxation step.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050254
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  • 8
    Electronic Resource
    Electronic Resource
    A scaling formalism for the representation of rotational energy transfer in OH (A2Σ+) in combustion experiments (1996)
    Springer
    Applied physics 63 (1996), S. 403-418 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 34.00
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract.  In order to predict spectra and temporal decays of the OH radical measured by Laser-Induced Fluorescence (LIF), the collisional energy transfer between different quantum states must be taken into account. At the elevated temperatures relevant for combustion studies, the large number of interacting quantum states and corresponding state-to-state energy transfer coefficients precludes the experimental measurement of all necessary information for the appropriate mixtures of colliders. Therefore, a scaling procedure has been devised which allows the representation of the matrix of Rotational Energy Transfer (RET) coefficients on the basis of measured data with four scaling coefficients. The scaling coefficients have been determined by comparison of the calculated RET rates with available measured data. The mathematical formalism for the scaling law – the ECS-EP law – is based on the Energy Corrected Sudden (ECS) law and includes an Exponential Power law (EP) for the representation of the basis coefficients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01828746
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  • 9
    Electronic Resource
    Electronic Resource
    Rate-equation modeling of single- and multiple-quantum vibrational energy transfer of OH (A 2Σ+, v′=0 to 3) (1999)
    Springer
    Applied physics 69 (1999), S. 61-70 
    Details
    ISSN: 1432-0649
    Keywords: PACS: 34.50.Ez; 82.40.Py
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. A computer code based on a kinetic rate-equation model for describing the collisional dynamics of OH (A 2Σ+) in laser-induced fluorescence experiments was developed. In this work, the capabilities of the simulation code are extended to include the vibrational states up to the OH (A 2Σ+, v′=3) level. The calculation of quenching, rotational and vibrational relaxation rate coefficients for different collider species is discussed. Problems that arise for the description of vibrational relaxation include the branching ratio between single- and multiple-quantum steps and the form of the nascent rotational distribution after a vibrational relaxation step. Experimental spectra recorded under a variety of conditions are simulated using a consistent set of model assumptions. The calculations must include vibrational relaxation steps up to Δv=3 to account for the experimental intensity distributions. Effects due to polarized laser excitation become more important for vibrational states with v′〉1. Areas for future work are identified, including determination of experimental rate coefficients for state-changing and depolarizing collisions in the upper vibrational levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003400050771
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  • 10
    Electronic Resource
    Electronic Resource
    Nitrogen atom detection in low-pressure flames by two-photon laser-excited fluorescence (1991)
    Springer
    Applied physics 52 (1991), S. 108-116 
    Details
    ISSN: 1432-0649
    Keywords: 82.40Py ; 33.50Dq
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Nitrogen atoms have been detected in stoichiometric flat premixed H2/O2/N2 flames at 33 and 96 mbar doped with small amounts of NH3, HCN, and (CN)2 using two-photon laser excitation at 211 nm and fluorescence detection around 870 nm. The shape of the fluorescence intensity profiles versus height above the burner surface is markedly different for the different additives. Using measured quenching rate coefficients and calibrating with the aid of known N-atom concentrations in a discharge flow reactor, peak N-atom concentrations in these flames are estimated to be on the order of 1012−5×1013 cm−3; the detection limit is about 1×1011 cm−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00357664
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