The multi-step resonance laser ionization is the most efficient and universal method used
to achieve the highest purity of ion beams delivered by isotope separators.
At ISOLDE on-line isotope separation facility, the Resonance Ionization Laser Ion Source
(RILIS) is the most commonly used ion source due to its unmatched combination of selectivity and efficiency.
A set of wavelength-tunable dye and Ti:Sapphire lasers, complemented by frequency mixing devices,
provides a vast opportunity for optimal choice of atomic transitions to build efficient ionization schemes.
By present time, ion beams of 48 elements have been produced at ISOLDE using RILIS.
The ion source configuration has evolved from a simple tubular hot cavity to advanced options such as
the Laser Ion Source and Trap (LIST) and the Versatile Arc Discharge and Laser Ion Source (VADLIS).
With these capabilities, the RILIS performance can be tailored for efficiency, selectivity or versatility,
depending on the requirements of the experiment. The RILIS application appears to be a must for the
absolute majority of physics experiments carried out at ISOLDE.
In addition, it is used as a high-sensitive instrument for probing the isotope shifts and hyperfine structure
of atomic transitions in unstable isotopes via so-called in-source laser spectroscopy.
This method is effectively applied for study the nuclear shape evolution via measuring the nuclear charge radii,
magnetic and quadrupole moments of isotopes far from stability.
The effects of shape coexistence and deformation onset are being studied in the gold-astatine region of the nuclear chart.
In the talk, the main features and capabilities of RILIS will be presented and illustrated by the nuclear and atomic
physics results obtained using the in-source spectroscopy method.