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Optogalvanic laser spectroscopy has been applied to measure the hyperfine structure of 13 spectral lines of Sc I in the wavelength range from 645 to 780 nm. Experimental magnetic dipole hyperfine structure constants A of the isotope 45 Sc have been determined for three levels of even and ten levels of odd parity. For six of these levels the A constants have been measured for the first time. For two further levels the A constants have already been measured but discrepancies between our values and the previous ones are found and discussed. With the new experimental results a parametric analysis of the magnetic dipole hyperfine structure has been performed for the even configuration 3d 2 4s and a very high value for the contact parameter a 10 3d has been found. Additionally, the experimental results for the other even levels are discussed.

Based on the experimental hyperfine structure data given in our previous study, the multi-configuration method has been used to calculate the fine structure of the odd parity configurations 3d4s4p, 4s 2 4p and 3d 2 4p of neutral Scandium taking into account configuration interaction effects. Magnetic dipole hyperfine structure constants are analysed in the effective-operator formalism for the isotope 45 Sc. Relativistic one-electron parameters of the magnetic dipole hyperfine structure a k s k l nl (k s k l = 01, 10, 12) were fitted to the experimental data by a least-squares fit procedure. Theoretical predictions for the magnetic dipole hyperfine structure constants A for all levels of the three configurations are given.

High resolution laser spectroscopy has been applied to study the hyperfine structure of excited levels of Tm I. In the wavelength range from 570 nm to 595 nm 31 transitions were measured using a hollow cathode discharge and a tunable single-mode cw ring dye laser. Precise values for the magnetic dipole hyperfine structure constants A of 24 even and 19 odd levels were determined.

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