We describe the current methods of superhigh-resolution spectroscopy based on interference of atomic states (quantum beats and level crossing) and compare them with the methods of Doppler-free laser spectroscopy. We pay major attention to the quantum-beat method, which has been developed in recent years in connection with progress in the technique of tunable lasers, and also to the phenomenon of alignment of atoms in a gasdischarge plasma. We treat examples of application of these methods for solving problems of superhigh-resolution spectroscopy.

@article{Aleksandrov:1979,
	author = {E. B. Aleksandrov and N. I. Kaliteevskii and M. P. Chaika},
	title = {Superhigh-resolution spectroscopy based on interference of states},
	publisher = {Physics-Uspekhi},
	year = {1979},
	journal = {Phys. Usp.},
	volume = {22},
	number = {9},
	pages = {760-767},
	url = {https://ufn.ru/en/articles/1979/9/f/},
	doi = {10.1070/PU1979v022n09ABEH005611}
}