High precision description of the rovibronic structure of the I$\mathsf{_2}$ B-X spectrum

Abstract.

A precise description of the B-X spectrum of the I₂ molecule has been developed. All presently available high precision measurements on the B-X spectrum of the I₂ molecule in the visible were introduced into a model based on molecular potentials for the two electronic states involved, the transition frequencies being the differences of the energy eigenvalues for the rovibrational levels in those potentials. This approach allows, depending on the quality of the input data, a prediction of iodine lines with a 2$\sigma$ uncertainty of less than 30 MHz from 514 nm to 815 nm of most bands in that range. In the range between 526 nm to 667 nm, where highly precise systematic measurements exist, a smaller 2$\sigma$ uncertainty of 3 MHz is achieved. Moreover, a precise local model description of selected bands of the B-X spectrum has been derived from high precision measurements of iodine lines in the near infrared between 778 nm and 815 nm. This approach by using a Dunham parameter description allows to predict lines of these bands with a 1$\sigma$ uncertainty of less than 200 kHz. All this information including the systematically studied hyperfine structure can be combined in a computer program for predicting the details of the iodine B-X spectrum with high reliability, serving as a convenient tool in spectroscopic calibration tasks.