Rotation Dependence of Electric Quadrupole Hyperfine Interaction in the Ground State of Molecular Iodine by High-Resolution Laser Spectroscopy

摘要

Doppler-free high-resolution spectroscopy is applied to molecular iodine at 532 nm by Nd:YAG lasers. The main hyperfine components as well as the crossover lines are measured for R(56)32−0 and P(54)32−0 transitions by heterodyne beating of two I2-stabilized lasers. The measured hyperfine splittings including both main and crossover lines are fitted to a four-term Hamiltonian, which includes the electric quadrupole, spin–rotation, tensor spin–spin, and scalar spin–spin interactions, with an average deviation of ∼1 kHz. Absolute values of the electric quadrupole hyperfine constants for both the upper and the lower states are obtained. The rotation dependence of the ground-state (vu22=0) electric quadrupole constant eQqu22 is found to be eQqu22(J)=−2452.556(2)−0.000164(5)J(J+1)−0.000000005(2)J2(J+1)2 MHz.