OSA's Digital Library

Journal of the Optical Society of America

Journal of the Optical Society of America

  • Vol. 55, Iss. 2 — Feb. 1, 1965
  • pp: 174–177

Absorption of 3.39-Micron Helium—Neon Laser Emission by Methane in the Atmosphere

BYRON N. EDWARDS and DARRELL E. BURCH  »View Author Affiliations


JOSA, Vol. 55, Issue 2, pp. 174-177 (1965)
http://dx.doi.org/10.1364/JOSA.55.000174


View Full Text Article

Acrobat PDF (499 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

The paper describes an experiment on the absorption of the 3S2-3P4 helium—neon laser emission at 2947.903 cm-1 (3.39µ) by methane. The emission frequency coincides closely to one of the components of the P(F+) branch of the ν3 band of methane. Methane and nitrogen in different mixing ratios were introduced into an absorption cell and the transmittance as a function of pressure was determined. By relating the measured absorption coefficient with the known interaction of collision and Doppler effects on the broadening of the absorption line, the separation of the emission line and the nearest absorption line was deduced to be 0.003±0.002 cm-1.

The collision broadened full-width at half-maximum of the absorption line was determined to be 0.13±0.04 cm-1 at atmospheric pressure. At 1 atm in the earth’s atmosphere, the transmittance can be calculated to be T = exp (-1.1 L) by using the published value of the concentration of methane where L is the path length in kilometers. The effects of the laser emission in several possible cavity modes and of the several absorption lines in the methane group which overlap each other at high pressures are discussed.

Citation
BYRON N. EDWARDS and DARRELL E. BURCH, "Absorption of 3.39-Micron Helium—Neon Laser Emission by Methane in the Atmosphere," J. Opt. Soc. Am. 55, 174-177 (1965)
http://www.opticsinfobase.org/josa/abstract.cfm?URI=josa-55-2-174


Sort:  Author  |  Journal  |  Reset

References

  1. W. R. Bennett, Jr., Appl. Opt. Suppl. 1, 24 (1962).
  2. C. E. Moore, Natl. Bur. Std. (U. S.), Circ. No. 467 (1949).
  3. E. K. Plyler, E. D. Tidwell, and L. R. Blaine, J. Res. Natl. Bur. Std. 64A, 201 (1960).
  4. K. T. Hecht, J. Mol. Spectry. 5, 390 (1960).
  5. E. K. Plyler (private communication).
  6. Bennett1 gives the full Doppler width at half maximum at 1.15 µ to be 800 Mc/sec where ΔνD = 2ν0[(2kT/Mc2) (ln2)]½. This corresponds to 270 Mc/sec at 3.39 µ (0.009 cm-1 at 2947 cm-1).
  7. A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1961).
  8. F. Hjerting, Astrophys. J. 88, 505 (1938).
  9. All widths are "full width at half maximum."
  10. Computed from formula for Doppler width with T =300°K. The Doppler widths of the neon transition and the methane absorption line are, by coincidence, approximately equal.
  11. U. Fink, D. H. Rank, and T. A. Wiggins, J. Opt. Soc. Am. 54, 472 (1964) give the amount of methane in a vertical path from sea level to be 1.11 atm cm (NTP). Since the total air content is 8×105 atm cm (NTP), the fractional concentration by volume of methane is 1.4×10-6 They find their results to be in good agreement with those of other workers for different altitudes and at different geographical locations.

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited