Abstract

Gas phase diagnostics with multispecies diatomic spectra is discussed. Analyses of spectra from the A 3ΠiX 3Σ- system of NH and the C 3ΠuB 3Πg second-positive system of N2 are presented. Multispecies spectroscopy is applied to experimental spectra obtained from laser-induced breakdown plasmas in anhydrous ammonia gas and a low-pressure discharge lamp.

© 1998 Optical Society of America

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References

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  1. J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “On the use of line strengths in applied diatomic spectroscopy,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 196–198.
  2. J. O. Hornkohl, C. Parigger, “Angular momentum states of the diatomic molecule,” Am. J. Phys. 64, 623–633 (1996).
    [CrossRef]
  3. J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Computation of synthetic diatomic spectra,” in Laser Applications to Chemical Analysis, Vol. 5 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 234–237.
  4. A. P. Thorne, Spectrophysics, 2nd ed. (Chapman & Hall, London, 1988), Table 11.1.
    [CrossRef]
  5. J. A. Nelder, R. Mead, “A Simplex method for function minimization,” Comput. J. 7, 308–313 (1965).
    [CrossRef]
  6. J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Temperature measurements from CN spectra in a laser-induced plasma,” J. Quant. Spectrosc. Radiat. Transfer 46, 405–411 (1991).
    [CrossRef]
  7. C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Spectroscopic temperature measurements in a decaying laser-induced plasma using the C2 Swan system,” J. Quant. Spectrosc. Radiat. Transfer 52, 707–711 (1994).
    [CrossRef]
  8. C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Temperature measurements using first-negative N2+ spectra produced by laser-induced multiphoton ionization and optical breakdown of nitrogen,” Appl. Opt. 34, 3331–3335 (1995).
    [CrossRef] [PubMed]
  9. C. R. Brazier, R. S. Ram, P. F. Bernath, “Fourier transform spectroscopy of the A3Π–X3Σ- transition of NH,” J. Mol. Spectrosc. 120, 381–402 (1986).
    [CrossRef]
  10. K. J. Rensberger, J. B. Jefferies, R. A. Copeland, K. Kohse-Höinghaus, M. L. Wise, D. R. Crosley, “Laser-induced fluorescence determination of temperatures in low pressure flames,” Appl. Opt. 28, 3556–3566 (1989).
    [CrossRef] [PubMed]
  11. F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2: analysis of the (0-0), (0-1), (0-2), and (0-3) bands of the C3Πu–B3Πg system,” Can. J. Phys. 67, 143–147 (1989).
    [CrossRef]
  12. F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2 violet emission: extensive analysis of the C3Πu–B3Πg system,” J. Mol. Spectrosc. 158, 270–277 (1993).
    [CrossRef]
  13. S. Gordon, B. J. McBride, “Computer program for calculation of complex equilibrium compositions, rocket performance, incident and reflected shocks, and Chapman-Jouguet detonations,” Interim Revision NASA Rep. SP-273 (NASA Lewis Research Center, Cleveland, Ohio, 1976).
  14. C. Parigger, J. W. L. Lewis, D. H. Plemmons, J. O. Hornkohl, “Nitric oxide optical breakdown spectra and analysis by the use of the program NEQAIR,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 85–87.
  15. C. Parigger, J. W. L. Lewis, D. H. Plemmons, G. Guan, J. O. Hornkohl, “Hydroxyl measurements in air-breakdown microplasmas,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 82–84.
  16. S. Yalçin, D. R. Crosley, G. P. Smith, W. Faris, “Spectroscopically determined temperatures and electron densities in laser produced sparks,” presented at the 1995 OSA Annual Meeting/ILS-XI Program, Portland, Oregon, September 1995.

1996 (1)

J. O. Hornkohl, C. Parigger, “Angular momentum states of the diatomic molecule,” Am. J. Phys. 64, 623–633 (1996).
[CrossRef]

1995 (1)

1994 (1)

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Spectroscopic temperature measurements in a decaying laser-induced plasma using the C2 Swan system,” J. Quant. Spectrosc. Radiat. Transfer 52, 707–711 (1994).
[CrossRef]

1993 (1)

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2 violet emission: extensive analysis of the C3Πu–B3Πg system,” J. Mol. Spectrosc. 158, 270–277 (1993).
[CrossRef]

1991 (1)

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Temperature measurements from CN spectra in a laser-induced plasma,” J. Quant. Spectrosc. Radiat. Transfer 46, 405–411 (1991).
[CrossRef]

1989 (2)

K. J. Rensberger, J. B. Jefferies, R. A. Copeland, K. Kohse-Höinghaus, M. L. Wise, D. R. Crosley, “Laser-induced fluorescence determination of temperatures in low pressure flames,” Appl. Opt. 28, 3556–3566 (1989).
[CrossRef] [PubMed]

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2: analysis of the (0-0), (0-1), (0-2), and (0-3) bands of the C3Πu–B3Πg system,” Can. J. Phys. 67, 143–147 (1989).
[CrossRef]

1986 (1)

C. R. Brazier, R. S. Ram, P. F. Bernath, “Fourier transform spectroscopy of the A3Π–X3Σ- transition of NH,” J. Mol. Spectrosc. 120, 381–402 (1986).
[CrossRef]

1965 (1)

J. A. Nelder, R. Mead, “A Simplex method for function minimization,” Comput. J. 7, 308–313 (1965).
[CrossRef]

Bernath, P. F.

C. R. Brazier, R. S. Ram, P. F. Bernath, “Fourier transform spectroscopy of the A3Π–X3Σ- transition of NH,” J. Mol. Spectrosc. 120, 381–402 (1986).
[CrossRef]

Brazier, C. R.

C. R. Brazier, R. S. Ram, P. F. Bernath, “Fourier transform spectroscopy of the A3Π–X3Σ- transition of NH,” J. Mol. Spectrosc. 120, 381–402 (1986).
[CrossRef]

Copeland, R. A.

Crosley, D. R.

K. J. Rensberger, J. B. Jefferies, R. A. Copeland, K. Kohse-Höinghaus, M. L. Wise, D. R. Crosley, “Laser-induced fluorescence determination of temperatures in low pressure flames,” Appl. Opt. 28, 3556–3566 (1989).
[CrossRef] [PubMed]

S. Yalçin, D. R. Crosley, G. P. Smith, W. Faris, “Spectroscopically determined temperatures and electron densities in laser produced sparks,” presented at the 1995 OSA Annual Meeting/ILS-XI Program, Portland, Oregon, September 1995.

Faris, W.

S. Yalçin, D. R. Crosley, G. P. Smith, W. Faris, “Spectroscopically determined temperatures and electron densities in laser produced sparks,” presented at the 1995 OSA Annual Meeting/ILS-XI Program, Portland, Oregon, September 1995.

Gordon, S.

S. Gordon, B. J. McBride, “Computer program for calculation of complex equilibrium compositions, rocket performance, incident and reflected shocks, and Chapman-Jouguet detonations,” Interim Revision NASA Rep. SP-273 (NASA Lewis Research Center, Cleveland, Ohio, 1976).

Guan, G.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, G. Guan, J. O. Hornkohl, “Hydroxyl measurements in air-breakdown microplasmas,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 82–84.

Hornkohl, J. O.

J. O. Hornkohl, C. Parigger, “Angular momentum states of the diatomic molecule,” Am. J. Phys. 64, 623–633 (1996).
[CrossRef]

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Temperature measurements using first-negative N2+ spectra produced by laser-induced multiphoton ionization and optical breakdown of nitrogen,” Appl. Opt. 34, 3331–3335 (1995).
[CrossRef] [PubMed]

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Spectroscopic temperature measurements in a decaying laser-induced plasma using the C2 Swan system,” J. Quant. Spectrosc. Radiat. Transfer 52, 707–711 (1994).
[CrossRef]

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Temperature measurements from CN spectra in a laser-induced plasma,” J. Quant. Spectrosc. Radiat. Transfer 46, 405–411 (1991).
[CrossRef]

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “On the use of line strengths in applied diatomic spectroscopy,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 196–198.

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Computation of synthetic diatomic spectra,” in Laser Applications to Chemical Analysis, Vol. 5 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 234–237.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, G. Guan, J. O. Hornkohl, “Hydroxyl measurements in air-breakdown microplasmas,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 82–84.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, J. O. Hornkohl, “Nitric oxide optical breakdown spectra and analysis by the use of the program NEQAIR,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 85–87.

Jefferies, J. B.

Kohse-Höinghaus, K.

Lewis, J. W. L.

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Temperature measurements using first-negative N2+ spectra produced by laser-induced multiphoton ionization and optical breakdown of nitrogen,” Appl. Opt. 34, 3331–3335 (1995).
[CrossRef] [PubMed]

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Spectroscopic temperature measurements in a decaying laser-induced plasma using the C2 Swan system,” J. Quant. Spectrosc. Radiat. Transfer 52, 707–711 (1994).
[CrossRef]

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Temperature measurements from CN spectra in a laser-induced plasma,” J. Quant. Spectrosc. Radiat. Transfer 46, 405–411 (1991).
[CrossRef]

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “On the use of line strengths in applied diatomic spectroscopy,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 196–198.

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Computation of synthetic diatomic spectra,” in Laser Applications to Chemical Analysis, Vol. 5 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 234–237.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, J. O. Hornkohl, “Nitric oxide optical breakdown spectra and analysis by the use of the program NEQAIR,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 85–87.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, G. Guan, J. O. Hornkohl, “Hydroxyl measurements in air-breakdown microplasmas,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 82–84.

McBride, B. J.

S. Gordon, B. J. McBride, “Computer program for calculation of complex equilibrium compositions, rocket performance, incident and reflected shocks, and Chapman-Jouguet detonations,” Interim Revision NASA Rep. SP-273 (NASA Lewis Research Center, Cleveland, Ohio, 1976).

Mead, R.

J. A. Nelder, R. Mead, “A Simplex method for function minimization,” Comput. J. 7, 308–313 (1965).
[CrossRef]

Michaud, F.

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2 violet emission: extensive analysis of the C3Πu–B3Πg system,” J. Mol. Spectrosc. 158, 270–277 (1993).
[CrossRef]

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2: analysis of the (0-0), (0-1), (0-2), and (0-3) bands of the C3Πu–B3Πg system,” Can. J. Phys. 67, 143–147 (1989).
[CrossRef]

Nelder, J. A.

J. A. Nelder, R. Mead, “A Simplex method for function minimization,” Comput. J. 7, 308–313 (1965).
[CrossRef]

Parigger, C.

J. O. Hornkohl, C. Parigger, “Angular momentum states of the diatomic molecule,” Am. J. Phys. 64, 623–633 (1996).
[CrossRef]

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Temperature measurements using first-negative N2+ spectra produced by laser-induced multiphoton ionization and optical breakdown of nitrogen,” Appl. Opt. 34, 3331–3335 (1995).
[CrossRef] [PubMed]

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Spectroscopic temperature measurements in a decaying laser-induced plasma using the C2 Swan system,” J. Quant. Spectrosc. Radiat. Transfer 52, 707–711 (1994).
[CrossRef]

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Temperature measurements from CN spectra in a laser-induced plasma,” J. Quant. Spectrosc. Radiat. Transfer 46, 405–411 (1991).
[CrossRef]

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “On the use of line strengths in applied diatomic spectroscopy,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 196–198.

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Computation of synthetic diatomic spectra,” in Laser Applications to Chemical Analysis, Vol. 5 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 234–237.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, J. O. Hornkohl, “Nitric oxide optical breakdown spectra and analysis by the use of the program NEQAIR,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 85–87.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, G. Guan, J. O. Hornkohl, “Hydroxyl measurements in air-breakdown microplasmas,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 82–84.

Plemmons, D. H.

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Temperature measurements using first-negative N2+ spectra produced by laser-induced multiphoton ionization and optical breakdown of nitrogen,” Appl. Opt. 34, 3331–3335 (1995).
[CrossRef] [PubMed]

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Spectroscopic temperature measurements in a decaying laser-induced plasma using the C2 Swan system,” J. Quant. Spectrosc. Radiat. Transfer 52, 707–711 (1994).
[CrossRef]

C. Parigger, J. W. L. Lewis, D. H. Plemmons, J. O. Hornkohl, “Nitric oxide optical breakdown spectra and analysis by the use of the program NEQAIR,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 85–87.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, G. Guan, J. O. Hornkohl, “Hydroxyl measurements in air-breakdown microplasmas,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 82–84.

Ram, R. S.

C. R. Brazier, R. S. Ram, P. F. Bernath, “Fourier transform spectroscopy of the A3Π–X3Σ- transition of NH,” J. Mol. Spectrosc. 120, 381–402 (1986).
[CrossRef]

Rensberger, K. J.

Roux, F.

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2 violet emission: extensive analysis of the C3Πu–B3Πg system,” J. Mol. Spectrosc. 158, 270–277 (1993).
[CrossRef]

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2: analysis of the (0-0), (0-1), (0-2), and (0-3) bands of the C3Πu–B3Πg system,” Can. J. Phys. 67, 143–147 (1989).
[CrossRef]

Smith, G. P.

S. Yalçin, D. R. Crosley, G. P. Smith, W. Faris, “Spectroscopically determined temperatures and electron densities in laser produced sparks,” presented at the 1995 OSA Annual Meeting/ILS-XI Program, Portland, Oregon, September 1995.

Thorne, A. P.

A. P. Thorne, Spectrophysics, 2nd ed. (Chapman & Hall, London, 1988), Table 11.1.
[CrossRef]

Vervloet, M.

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2 violet emission: extensive analysis of the C3Πu–B3Πg system,” J. Mol. Spectrosc. 158, 270–277 (1993).
[CrossRef]

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2: analysis of the (0-0), (0-1), (0-2), and (0-3) bands of the C3Πu–B3Πg system,” Can. J. Phys. 67, 143–147 (1989).
[CrossRef]

Wise, M. L.

Yalçin, S.

S. Yalçin, D. R. Crosley, G. P. Smith, W. Faris, “Spectroscopically determined temperatures and electron densities in laser produced sparks,” presented at the 1995 OSA Annual Meeting/ILS-XI Program, Portland, Oregon, September 1995.

Am. J. Phys. (1)

J. O. Hornkohl, C. Parigger, “Angular momentum states of the diatomic molecule,” Am. J. Phys. 64, 623–633 (1996).
[CrossRef]

Appl. Opt. (2)

Can. J. Phys. (1)

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2: analysis of the (0-0), (0-1), (0-2), and (0-3) bands of the C3Πu–B3Πg system,” Can. J. Phys. 67, 143–147 (1989).
[CrossRef]

Comput. J. (1)

J. A. Nelder, R. Mead, “A Simplex method for function minimization,” Comput. J. 7, 308–313 (1965).
[CrossRef]

J. Mol. Spectrosc. (2)

F. Roux, F. Michaud, M. Vervloet, “High-resolution Fourier spectrometry of 14N2 violet emission: extensive analysis of the C3Πu–B3Πg system,” J. Mol. Spectrosc. 158, 270–277 (1993).
[CrossRef]

C. R. Brazier, R. S. Ram, P. F. Bernath, “Fourier transform spectroscopy of the A3Π–X3Σ- transition of NH,” J. Mol. Spectrosc. 120, 381–402 (1986).
[CrossRef]

J. Quant. Spectrosc. Radiat. Transfer (2)

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Temperature measurements from CN spectra in a laser-induced plasma,” J. Quant. Spectrosc. Radiat. Transfer 46, 405–411 (1991).
[CrossRef]

C. Parigger, D. H. Plemmons, J. O. Hornkohl, J. W. L. Lewis, “Spectroscopic temperature measurements in a decaying laser-induced plasma using the C2 Swan system,” J. Quant. Spectrosc. Radiat. Transfer 52, 707–711 (1994).
[CrossRef]

Other (7)

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “Computation of synthetic diatomic spectra,” in Laser Applications to Chemical Analysis, Vol. 5 of 1994 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1994), pp. 234–237.

A. P. Thorne, Spectrophysics, 2nd ed. (Chapman & Hall, London, 1988), Table 11.1.
[CrossRef]

S. Gordon, B. J. McBride, “Computer program for calculation of complex equilibrium compositions, rocket performance, incident and reflected shocks, and Chapman-Jouguet detonations,” Interim Revision NASA Rep. SP-273 (NASA Lewis Research Center, Cleveland, Ohio, 1976).

C. Parigger, J. W. L. Lewis, D. H. Plemmons, J. O. Hornkohl, “Nitric oxide optical breakdown spectra and analysis by the use of the program NEQAIR,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 85–87.

C. Parigger, J. W. L. Lewis, D. H. Plemmons, G. Guan, J. O. Hornkohl, “Hydroxyl measurements in air-breakdown microplasmas,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 82–84.

S. Yalçin, D. R. Crosley, G. P. Smith, W. Faris, “Spectroscopically determined temperatures and electron densities in laser produced sparks,” presented at the 1995 OSA Annual Meeting/ILS-XI Program, Portland, Oregon, September 1995.

J. O. Hornkohl, C. Parigger, J. W. L. Lewis, “On the use of line strengths in applied diatomic spectroscopy,” in Laser Applications to Chemical, Biological and Environmental Analysis, Vol. 3 of 1996 OSA Technical Digest Series (Optical Society of America, Washington, D.C., 1996), pp. 196–198.

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Figures (10)

Fig. 1
Fig. 1

Low-resolution theoretical spectrum that shows the content of our N2 second-positive system line strength file. The calculation was performed for a rotational temperature of 450 K and a vibrational temperature of 4500 K to enhance the vibrational band structure. The Gaussian linewidth of this spectrum is 10 cm-1 FWHM.

Fig. 2
Fig. 2

(a) High-resolution (0.1 cm-1 FWHM) theoretical spectrum of a portion of the N2 second-positive system with T r = T v = 450 K. (b) Experimental spectrum of Roux et al.11 The alternation of intensities produced by nuclear spin statistics can be observed for a Λ-doubled spectrum only when the Λ doublets are resolved. A factor of 2 intensity alternation (i.e., a nuclear spin of 1) can be seen in both Roux et al.’s experimental spectrum and the synthetic spectrum.

Fig. 3
Fig. 3

Nonequilibrium NH–N2 experimental and theoretical spectra with T r = 570 K, T v = 4200 K, and (N2)/(NH) = 4.7.

Fig. 4
Fig. 4

Experimental spectrum and a theoretical spectrum calculated from the parameters resulting from a spectral fit to λ ≥ 338 nm. The theoretical spectrum underpredicts the experiment in the region of the N2 second-positive system. The expected N2 contribution is shown along the bottom of the figure. The Gaussian linewidth of the theoretical spectra is 15.5 cm-1.

Fig. 5
Fig. 5

Fitting only NH to the experimental spectrum causes the theory to underpredict the intensity in the middle of the spectrum, which contains the N2 contribution, and overpredict the intensity in the spectral region, which contains no N2 contribution. The Gaussian linewidth of the theoretical spectra is 15.5 cm-1.

Fig. 6
Fig. 6

Experimental spectrum and a theoretical NH–N2 fit. The theory slightly overpredicts the intensity in the region of the NH 2–2 band (λ ≃ 339.3 nm). The Gaussian linewidth of the theoretical spectra is 15.5 cm-1.

Fig. 7
Fig. 7

Inferred temperatures versus laser-pulse energy absorbed by the optical breakdown plasma: filled circles, 0.5–1.0-μs delay; open squares, 1.0–2.0-μs delay.

Fig. 8
Fig. 8

NH–N2 signal versus laser-pulse energy absorbed by the optical plasma: filled circles, 0.5–1.0-μs delay; open squares, 1.0–2.0-μs delay.

Fig. 9
Fig. 9

Spatially resolved NH–N2 spectra.

Fig. 10
Fig. 10

Inferred temperatures across the optical breakdown plasma.

Equations (2)

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I total = I 1 + RI 2 ,
N 2 0 N 1 0 = R   Q 2 Q 1 ,

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