Hyperfine Structure of Thallium Iodide and an Upper Limit for the Electric Hexadecapole Moment of the Iodine Nucleus

Abstract

The hyperfine structure of thallium iodide has been studied in the J = 3J=3 and J = 4J=4 rotational states in an attempt to observe a nuclear electric hexadecapole effect. This study was carried out on a high‐resolution molecular‐beam electric resonance spectrometer at very weak electric and magnetic fields. The molecule is well described by the usual five hyperfine interaction constants which are (in kilohertz) 205Tl127I203Tl127IeqQ−438916.3±0.5−438917.3±1.0c13.05±0.053.09±0.1c234.65±0.1534.36±0.3c3−2.48±0.1−2.59±0.2c4−6.67±0.05−6.57±0.1. No evidence for a hexadecapole interaction constant as large as 500 Hz was found; this result is interpreted as setting an upper limit of ∼ 10−47 cm4 for the nuclear electric hexadecapole moment of 127I.