Faint Lines in the Arc Spectrum of Iron (Fe I)

A search for new faint iron lines has been made on spectrograms taken with an arc-in-air as source. The range of observations is from 2102 to 8679 A. The reciprocal dispersion of the spectrographs used for the various spectral regions varies from 1 A/mm to 3 A/mm. Twelve new energy levels have been found, resulting in a total of 121 classified lines. A table containing 698 classified lines includes many lines whose wavelengths had been predicted as combinations among the known energy levels, and found in the solar spectrum in earlier work. Their reality has been confirmed in the present work. A list containing 1,102 newly measured unclassified lines is included. Many of the lines listed in the tables have been reported by other observers with varying degrees of accuracy. All such reference sources are indicated in the tables. As a result of the new measurements, these lines may safely be attributed to Fe I. A comparison of the new lines with the solar spectrum has resulted in the identification of 306 solar lines of Fe I unblended, and of 85 as blends to which Fe I is a contributor.