Fourteen new spectral lines of Zr IV lying between 3200 and 4600 Å were observed with a sliding spark discharge and a 10.7-m normal-incidence spectrograph. The lines were classified as transitions between highly excited energy levels of this ion. The measured wavelengths provide improved values for the known energy levels as well as a value for the previously unknown 6h <sup>2</sup>H term. Wavelengths with standard uncertainties varying from ±0.0005 to ±0.0018 Å were determined from the optimized level values for a group of lines between 445 and 1291 Å. An improved ionization energy was determined as 277 602.8±0.5 cm<sup>−1</sup> (34.41837± 0.00006 eV).
© 1997 Optical Society of America
Joseph Reader and Nicolo Acquista, "Long-wavelength transitions and improved energy levels of triply ionized zirconium (Zr IV)," J. Opt. Soc. Am. B 14, 1328-1330 (1997)