Ultraviolet solar identifications based on extended absorption series observed in the laboratory spectrum of Si I

The absorption spectrum of Si I in the wavelength region 1500-1900A has been photographed at high resolution. The silicon vapour was produced in a 122 cm long King furnace at 1800-23000C. Forty-two Rydberg series have been observed from the ground state terms 3p23P and 1D to terms associated with the 3 pns and 3pnd configurations. All of the series from these configurations with J<4 have been extended with the 3pnd3D30 levels reaching n=56. Numerous perturbations have been observed. This laboratory work has provided the basis for extending the identification of silicon lines in the solar spectrum. Nearly all lines found in the laboratory spectrum are also found in rocket spectrograms of the solar chromosphere. More than 300 lines have been attributed to Si I. The excellent correlation between laboratory and solar Si I lines is illustrated. (Auth.)