578 



TABLE 620.— WAVELENGTHS OF FRAUNHOFER LINES (concluded) 



Solar 

 wavelength 



4307.912 



4307.747 



4226.740 t 



4101.748 



3968.492 



3933.682 



3820.436 



3727.634 



3581.209 



3441.019 



3361.193 



3286.772 



3181.276 



3179.342 



3143.996 



3143.764 



3101.895 



3101.574 



3100.682 



3100.325 



3099.987 



3099.896 



3047.614 



3021.077 



3020.656 



3020.490 



2994.436 



Solar 

 intensity 



6 



3 



20d 

 40X 

 700 

 1000 

 25 



4 



30 

 15 



8 



7N 



3 



5d? 



2 



4 



3 



4N 



3 



4N 



3 



3 



35 

 30 

 40 

 20 

 40 



* Band lines due to molecular oxygen in the earth's atmosphere. The wavelength of the first line of 

 the band is recorded here. 



t Laboratory wavelengths listed. He lines are conspicuous in the spectrum of the chromosphere, 

 t Rowland assigns the index letter "g " to this line. 



REFERENCES FOR STANDARD WAVELENGTHS 



177 Trans Int. Union Coop. Solar Res., vol. 2, p. 142, 1907. 



178 Trans. Int. Astron. L'nion, vol. 1, p. 35. 1922. 



178 Proces Verbaux Comite Int. Poids et Mesures, Ser. 2, vol. 12, p. 67, 1927. 



180 Ibid., vol. 17. p. 91, 1935. 



181 Proc. Roy. Soc. London, vol. A186, p. 164, 1946. 



" 2 Journ. Opt. Soc. Amer., vol. 38, p. 7, 1948; vol. 40, p. 545, 1950. Comptes Rendus, vol. 228, p. 



964, 1949. 

 183 Trans. Int. Astron. Union, vol. 5, p. 86, 1935. 

 1M Ibid., vol. 5, p. 87, 1935. 

 188 Ibid., vol. 1, p. 36, 1922. 

 1M Ibid., vol. 3, p. 86, 1928; vol. 4, p. 234, 1932; vol. 6, p. 79, 1938. 



187 Ibid., vol. 5, p. 84, 1935; vol. 7, p. 146, 1949. 

 1M Ibid., vol. 6, p. 80, 1938. 



188 Ibid., vol. 1, p. 41, 1922; vol. 2, p. 42, 1925. 

 1U0 Phys. Rev., vol. 47, p 653, 1935. 



m Trans. Int. Astron. Union, vol. 3, p. 93, 1928; vol. 6, p. 90, 1938. 

 182 Philos. Trans., vol. 177, p. 457, 1886. 



Series relations in atomic spectra. — The analysis of atomic spectra began in 1889 

 when J. R. Rydberg first found that the wave number (number of waves per cm) of a 

 spectral line could be represented as the difference between two numerical quantities that 

 he called spectral terms. From the data of alkali and alkaline-earth spectra Rydberg 



sorted singlet, doublet, and triplet terms that formed sequences of the form ; — ; — rj> 



where R is Rydberg's constant, n is an integer, and n a fraction. Rydberg also distin- 

 guished between sharp, principal, and diffuse terms; the initial letters s, p, and d survive 

 in spectroscopic notation today. To distinguish between successive terms of a series, 

 cardinal numbers (n) were prefixed to the literal symbols, and to distinguish between the 

 components of doublet and triplet terms numerical subscripts were arbitrarily attached. 



SMITHSONIAN PHYSICAL TABLES 



