Accuratef‐Values for Ultraviolet Transitions from the 3d{aastex} {amsbsy} {amsfonts} {amssymb} {bm} {mathrsfs} {pifont} {stmaryrd} {textcomp} {portland,xspace} {amsmath,amsxtra} [OT2,OT1]{fontenc} { {wncyr} {wncyss} {OT2} } {}{} {empty} {10}{9}{7}{6} {document} ⁵ {document} ( {aastex} {amsbsy} {amsfonts} {amssymb} {bm} {mathrsfs} {pifont} {stmaryrd} {textcomp} {portland,xspace} {amsmath,amsxtra} [OT2,OT1]{fontenc} { {wncyr} {wncyss} {OT2} } {}{} {empty} {10}{9}{7}{6} {document} ⁶ {document}S)4pLevels in Mn ii

We have measured branching fractions for ultraviolet electric dipole transitions from upper levels belonging to the 3 d 5 ( 6 S )4 p 7 P and 3 d 5 ( 6 S )4 p 5 P terms of Mn II. The levels were excited in a hollow cathode lamp and the spectra were observed with a Fourier transform spectrometer. The high signal-to-noise ratio of the Mn II lines in our spectra permitted the measurement of branching fractions even for the weakest transitions in the ultraviolet, which are of particular astrophysical interest. A comparison with previous measurements revealed that many of these measurements, including the most recent, show systematic distortions that may indicate that they are affected by self-absorption. Absolute oscillator strengths, based on the new branching fraction measurements, were determined using existing experimental lifetime data. The uncertainty of the f -values is less than 5% for strong transitions. Oscillator strengths for several very weak intercombination lines with log gf < -2 are reported for the first time.