Extension of absolute-frequency measurements to the visible: frequencies of ten hyperfine components of iodine

Abstract

Direct-frequency measurements have been extended into the visible region of the electromagnetic spectrum. The visible frequencies were synthesized by generating the second harmonic of the recently measured 260-THz (20)Ne, 1.15-microm laser with a LiNbO(3) crystal. The absolute frequencies of ten hyperfine components of (127)I(2) near 520 THz are reported.