J dependence of predissociation rates and hyperfine constants as measured by high resolution laser spectroscopy

Highly excited rotational states in electronically excited bromine molecules are measured with full hyperfine resolution, by means of sub-Doppler polarization spectroscopy. The dependence of molecular parameters such as predissociation rates and hyperfine coupling constants on the rotational quantum number is extracted, and found to be proportional to the rotational energy J(J+1), extending previous data to much higher rotational states. By fitting a large set of hyperfine resolved rotational spectra from one vibrational band to a single set of parameters, very small dependencies may be extracted. The predissociation rates measured here in the frequency domain are compared to previous measurements in the time domain, and found to be smaller by more than an order of magnitude. We show that extracting decay times from lines of unresolved hyperfine structure may be misleading, and attribute this discrepancy to dephasing due to interferences between hyperfine components