Measured dispersion curves and the Rabi energies. The dispersion curves of the four samples having 1 mg SR101 (solid gray circles), 2 mg (solid black circles), 3 mg (empty red circles), and 4 mg (solid red circles) measured by D1 (a) and D2 (b). Empty black circles represent the dispersion relation for the sample without SR101 molecule measured at D1. Solid black horizontal lines are the SR101 absorption maximum and the absorption shoulder energies. The insets show the low (a) and high (b) energy splits as a function of (absorbance)1/2 with linear fits. Black dots correspond to D1, and red dots correspond to D2. Each curve corresponds to a single measured sample, and the error bars represent the estimated uncertainty of the measurement instruments (goniometric tool scale reading and wavelength determination).