The possibility of creating a frequency standard at the forbidden transition 23S-11S(62.6 nm) of a helium atom using stimulated Raman scattering has been shown. The singlet state 11S is the ground state and the metastable state 23S (He*) has the lowest energy in the spectrum triplet part. The standard can be used to measure frequencies in the region of extreme ultraviolet and, possibly, X-ray radiation.
- frequency comb, extreme ultraviolet
- frequency standard
- stimulated Raman scattering
- frequency comb
- extreme ultraviolet