Deep laser cooling of atoms, ions, and molecules facilitates the study of fundamental physics as well as applied research. In this work, we report on the narrow-line laser cooling of thulium atoms at the wavelength of $506.2\mathrm{nm}$ with the natural linewidth of $7.8\mathrm{kHz}$, which widens the limits of atomic cloud parameters control. Temperatures of about $400\mathrm{nK}$, phase-space density of up to $3.5\times {10}^{-4}$ and $2\times {10}^6$ number of trapped atoms were achieved. We have also demonstrated formation of double cloud structure in an optical lattice by adjusting parameters of the $506.2\mathrm{nm}$ magneto-optical trap. These results can be used to improve experiments with BEC, atomic interferometers, and optical clocks.

A scheme is proposed for the third stage of laser cooling of thulium atoms at a wavelength of 506.2 nm, and a system for stabilising the laser radiation frequency is described, which provides the required characteristics. The transition at a wavelength of 506.2 nm is detected in a magneto-optical trap with the employment of the developed laser setup. The value of hyperfine splitting of the transition upper level is measured, and the single-dimension cooling at this wavelength is observed for the first time.

In this paper, we demonstrate the interaction of 674 nm laser radiation with a clock quadrupole transition in high-energy ⁸⁸Sr⁺ ions obtained by laser ablation. The results of the spectrometry of the clock and the pump transitions are presented. We describe the parameters of the experimental setup and the protocol of the clock transition spectroscopy and analyze various line broadening mechanisms.

We demonstrate a simple and efficient readout procedure of the 1.14^m clock transition excitation efficiency in neutral thulium atoms. Our method utilizes additional but short clock n-pulse to measure number of atoms excited by spectroscopic clock pulse, that allows to determine excitation probability insensitive to fluctuation of number of atoms in the trap. It is important that this method can be used for both hyperfine components of the clock transition and does not require any additional lasers in the setup.