This article reviews recent developments in tests of fundamental physics using atoms and
molecules, including the subjects of parity violation, searches for permanent electric dipole …

We have performed two-photon ultraviolet direct frequency comb spectroscopy on the 1S-3S
transition in atomic hydrogen to illuminate the so-called proton radius puzzle and to …

The neutron-rich He 6 and He 8 isotopes exhibit an exotic nuclear structure that consists of a
tightly bound He 4-like core with additional neutrons orbiting at a relatively large distance …

At the core of the “proton radius puzzle” is a four–standard deviation discrepancy between
the proton root-mean-square charge radii (rp) determined from the regular hydrogen (H) and …

The spectroscopic hyperfine constants for all the alkali atoms are reported. For atoms from
lithium to cesium, only the long lived atomic isotopes are examined. For francium, the …

We report a new measurement of the positronium (Ps) 2 S 3 1→ 2 P 3 0 interval. Slow Ps
atoms, optically excited to the radiatively metastable 2 S 3 1 level, flew through a microwave …

The 2 S 3–2 P 3 transition of He 4 was measured by comb-linked laser spectroscopy using a
transverse-cooled atomic beam. The centroid frequency was determined to be 276 736 495 …

We investigate the 2 S 1 3–2 PJ 3 (J= 0, 1, 2) transitions in Li+ 6 using the optical Ramsey
technique and achieve the most precise values of the hyperfine splittings of the 2 S 1 3 and …

Nuclear charge radius differences in the silver isotopic chain have been reported through
different combinations of experiment and theory, exhibiting a tension of two combined …

We present absolute frequency measurements of the 1 P 1← 1 S 0 (229-nm) and 3 P 1← 1
S 0 (326-nm) transitions for all naturally occurring isotopes of cadmium. The isotope shifts …