Accuratef‐Values for Ultraviolet Transitions from the 3d\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $^{5}$ \end{document} ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $^{6}$ \end{document}S)4pLevels in Mnii

Abstract

We have measured branching fractions for ultraviolet electric dipole transitions from upper levels belonging to the 3d5(6S)4p7P and 3d5(6S)4p5P 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.