The K␣ 1,2 and K␤ 1,3 emission spectra of the 3d transition metals Cr, Mn, Fe, Co, Ni, and Cu were measured, employing a single-crystal diffractometer optimized for minimal instrumental broadening. The high-accuracy diffractometer, and the interferometrically calibrated silicon crystal employed ensure absolute wavelengths in the metric scale to a sub-part-per-million accuracy. An accurate analytic representation of each line, obtained by a fit to a minimal set of Lorentzians, is presented. The absolute energies, linewidths, and indices of asymmetry, derived from the data, agree well with previous measurements. So do also the intensity ratios K␣ 2 /K␣ 1 and K␤ 1,3 /K␣ 1,2 , which are, however, slightly, but consistently, higher than previous values. Possible origins for the observed Z-dependent trends are discussed. ͓S1050-2947͑97͒03012-6͔PACS number͑s͒: 32.30. Rj, 32.80.Hd, 31.30.Jv II. EXPERIMENT A. Measurement setupThe measurements were performed using a high-precision single-crystal spectrometer ͓11͔ in the classical Bragg geometry. The instrument is of a high mechanical stability. Its

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