The static Stark effect was investigated at very high electric fields of up to 690 kV/cm in the near-infrared lines between the levels of the $2s^{2}2p^2(3s,3p)$ configurations in the 742.36–939.28-nm spectral range, allowing us to obtain values of the differences of the scalar polarizabilities $\mathrm{\Delta }{\alpha }_0$. For the investigated lines, values were found to be very small, ranging from 30 to $200\mathrm{kHz}/{(\mathrm{kV}/\mathrm{cm})}^2$, while the tensor polarizabilities ${\alpha }_2$, associated with the splitting of the $\mathrm{\Delta }M$ line components, were found to be very small and not within the capabilities of the current experiment. Based on the most recent available atomic data, the polarizabilities ${\alpha }_0$ and ${\alpha }_2$ have been calculated for the investigated excited states, where significant differences were found with the current experiment. Values that were significantly more precise were obtained by fitting the polarizibility values of each level separately to match the values of the polarizibility differences observed in the experiment. For the experimentally investigated excited states of the $2s^{2}2p^{2}3s$ configuration, the scalar polarizabilities ${\alpha }_0$ were found to be in a range of 77 to $108\mathrm{kHz}/{(\mathrm{kV}/\mathrm{cm})}^2$, and 108 to $308\mathrm{kHz}/{(\mathrm{kV}/\mathrm{cm})}^2$ for the states of the $2s^{2}2p^{2}3p$ configuration. Values for the excited states are one and two orders of magnitude higher than those for the ground state. With the help of these data, predictions of Stark shifts for the remaining lines between the levels of both configurations have been made.

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• Atomic & molecular processes in external fields
• Stark effect
• Polarizability
• Optical spectroscopy