An experimental study of the collisional broadening of the Na-D lines by Ar and N2 perturbers in flames and vapor cells—II. The line wings |
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Authors: | MJ Jongerius Tj Hollander CThJ Alkemade |
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Institution: | Fysich Laboratorium, Rijksuniversiteit Utrecht, Princetonplein 5, 3584 CC Utrecht, The Netherlands |
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Abstract: | In this paper, we report on measurements of the fluorescence-excitation profile of the red Na-D1 line wing from about 1 cm?1 to 1100 cm?1 and of the blue Na-D2 line-wing from about 1 cm?1 to 600 cm?1, with respect to the corresponding line centre. We have also measured the fluorescence-excitation profile of the red Na-D2 and blue Na-D1 inner (overlapping) line wings from 1 cm?1 with respect to the centre of each of the lines. All these wings were measured in several premixed, laminar, shielded H2O2Ar and H2O2N2 flames at 1 atm (1400 K ? T ? 2300 K). We also measured these wings in a vapor cell containing Ar or N2 perturbers (T ~ 480 K, p ~ 0.4 atm) in order to determine the influence of temperature on these wings. Using a tunable CW dye laser as excitation source, we determined the fluorescence-excitation profiles by measuring the total fluorescence intensity while tuning the laser wavelength. In order to specify the contributions that the different kinds of major flame perturbers (Ar, N2, H2O) make to the wings, we compared the wing profiles measured in various flames of different flame-gas compositions. In this comparison, the wing profiles were normalized with respect to the line-centre. We compared our measurements of far red Na-D1 and blue Na-D2 line-wings () specified to Ar perturbers (at T = 500 K and T = 2000 K) with the results derived from quasi-static theory using available interaction potential data. In the case of Ar perturbers at T = 500 K, we observed a satellite at about 8 cm?1 from the line-centre on the red Na-D1 wing: this satellite was absent at T = 2000 K. The position of this red satellite was explained with the help of a set of “modified” potentials, which were constructed for interpreting the collisional Na-D broadening- and shift-rates deduced from our line-core observations and which were reported in Part I of this paper. |
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