High lying configurations in the spectrum of three times ionized indium (In IV)

•High resolution spectrum of In excited in vacuum spark was recorded below 700 Å.•Transitions from highly lying configurations in In IV are identified.•Energy levels are derived from identified In IV wavelengths.•Configuration interaction calculations are made for interpretation of In IV spectrum.

Using the high resolution vacuum normal and grazing incidence spectrographs the spectrum of three times ionized indium has been studied in the wavelength region 250-700 Å. Previously unknown transitions 4d95s-4d85s5p and 4d95p-4d98s were investigated resulting in the identification of 146 spectral lines and location of 55 levels of the 4d85s5p configuration and all four levels of the 4d98s configuration. The number of identified lines involving the 4d97s, 4d96p, 4d97p, 4d96d, 4d94f and 4d95f configurations was significantly increased. Previously found levels of these configurations were confirmed except two 4d96d levels which were corrected. Overall 210 new lines were identified in In IV.