UV continuum emission and diagnostics of hydrogen-containing non-equilibrium plasmas

For the first time the emission of the radiative dissociation continuum of the hydrogen molecule ($a^{3}\Sigma_{g}^{+} \to b^{3}\Sigma_{u}^{+}$ electronic transition) is proposed to be used as a source of information for the spectroscopic diagnostics of non-equilibrium plasmas. The detailed analysis of excitation-deactivation kinetics, rate constants of various collisional and radiative transitions and fitting procedures made it possible to develop two new methods of diagnostics of: (1) the ground $X^{1}\Sigma_{g}^{+}$ state vibrational temperature $T_{\text{vib}}$ from the relative intensity distribution, and (2) the rate of electron impact dissociation (d[\mbox{H_{2}}]/dt)_{\text{diss}} from the absolute intensity of the continuum. A known method of determination of $T_{\text{vib}}$ from relative intensities of Fulcher-$\alpha$ bands was seriously corrected and simplified due to the revision of $d \to a$ transition probabilities and cross sections of $d \gets X$ electron impact excitation. General considerations are illustrated with examples of experiments in pure hydrogen capillary-arc and H$_{2}$+Ar microwave discharges.Comment: REVTeX, 25 pages + 12 figures + 9 tables. Phys. Rev. E, eprint replaced because of resubmission to journal after referee's 2nd repor

Optimal values of rovibronic energy levels for triplet electronic states of molecular deuterium

Optimal set of 1050 rovibronic energy levels for 35 triplet electronic states of $D_2$ has been obtained by means of a statistical analysis of all available wavenumbers of triplet-triplet rovibronic transitions studied in emission, absorption, laser and anticrossing spectroscopic experiments of various authors. We used a new method of the analysis (Lavrov, Ryazanov, JETP Letters, 2005), which does not need any \it a priory \rm assumptions concerning the molecular structure being based on only two fundamental principles: Rydberg-Ritz and maximum likelihood. The method provides the opportunity to obtain the RMS estimates for uncertainties of the experimental wavenumbers independent from those presented in original papers. 234 from 3822 published wavenumber values were found to be spurious, while the remaining set of the data may be divided into 20 subsets (samples) of uniformly precise data having close to normal distributions of random errors within the samples. New experimental wavenumber values of 125 questionable lines were obtained in the present work. Optimal values of the rovibronic levels were obtained from the experimental data set consisting of 3713 wavenumber values (3588 old and 125 new). The unknown shift between levels of ortho- and para- deuterium was found by least squares analysis of the $a^3\Sigma_g^+$, $v = 0$, $N = 0 \div 18$ rovibronic levels with odd and even values of $N$. All the energy levels were obtained relative to the lowest vibro-rotational level ($v = 0$, $N = 0$) of the $a^3\Sigma_g^+$ electronic state, and presented in tabular form together with the standard deviations of the empirical determination. New energy level values differ significantly from those available in literature.Comment: 46 pages, 9 picture

Spectroscopical diagnostics of molecular microwave plasmas

The paper presents a review of recent results of emission (UV/visible) and absorption (visible and IR) spectroscopical investigations in molecular tube and planar microwave discharges. As a new approach by emission spectroscopy seven band systems of the hydrogen molecule have been analysed to investigate H2 radiative characteristics and to determine the gas temperature completed by Doppler broadening measurements of Hα, Dα and H2 spectral lines. H2 dissociation continuum was used for an estimation of the radiative dissociation rate/degree. By absorption spectroscopy the populations of 4s ArI levels and concentrations of hydrocarbons (e.g. CH3, C2H2, CH4) were determined. In particular, investigations were focused on spatial distributions of plasma parameters.La publication présente un aperçu de nouveaux résultats de mesures de spectroscopie démission (UV/visible) et d'absorption (visible et Infrarouge) dans des décharges microondes moléculaires dans des tubes et en structure plane. La nouveauté consiste en l'analyse de l'émission de système à sept bandes de la molécule d'hydrogène. On étudie ainsi les caractéristiques radiatives de H2 et on détermine la température du gaz par des mesures d'élargissement Doppler des lignes spectrales de Hα, Dα et H2. Le continuum de dissociation de H2 est utilisé pour estimer le degré de dissociation radiative. Les populations des niveaux 4s de l'Ar I et les concentrations des hydrocarbures (par exemple CH3, C2H2, CH4) sont déterminés par spectroscopie d'absorption. En particulier on s'est intéressé à la distribution spatiale des paramètres du plasma

Verbundprojekt: Grundlagenuntersuchungen zu neuartigen Füllungen für Hochdrucklampen und Wechselwirkung mit Gefäßwänden, Teilvorhaben: Experimentelle und Modelluntersuchungen zur Molekülstrahlung : Schlußbericht ; Laufzeit: 01.08.98 - 31.01.02

[no abstract available