HYPERFINE-STRUCTURE AND ISOTOPE SHIFT OF THE 640.2 AND 626.6 NM LINES OF NEON

A tunable single mode laser was used to excite the lambda equals 640. 2 and 626. 6 nm lines of **2**0Ne, **2**1Ne and **2**2Ne. Using the velocity selective optical pumping method, the hyperfine structures and isotopic shifts of these lines were measured obtaining the following values for the **2**1Ne hyperfine structure constants of the 2p//9 level: A(2p//9) equals minus 142. 5 plus or minus 1. 5 MHz, B(2p//9) equals minus 113 plus or minus 8 MHz. Isotope shifts were also measured and obtained values in good agreement with the mass-shift formula.