抄録
Four emissions intrinsic to ruby crystals were studied. Two of them were R1, and R2 lines. One of the other two emissions located at 14,980 cm−1 was ascribed to the transition from the 2F1 state. Another broad emission located at about 16,100 cm−1 was tentatively assigned to the emission corresponding to the U absorption band.
The temperature dependences of the relative intensities of these emissions were measured. Thereby, the population in the emitting states was found to be in apparent thermal equilibrium. A comparison of the quantum yield of these emissions excited by the light in the U band with that by the light in the R lines revealed that a competing process exists against the transition from the 4F2 to the 2E state.
The mechanisms of the excitation of the emissions were analyzed. It was concluded that the three processes, i. e. the transition from an optically excited state to the emitting states, the achievement of the thermal equilibrium of populations in the emitting states, and thermal quenchings of the emissions, are all caused by non-radiative transitions through the 4F2 state.
As a result of the analysis some of the frequency factors for these transitions were determined, which agree fairly well with the results of calculations based on the presently known theories. It was pointed out that the frequency factor for the “spin forbidden” transition is smaller by two orders of magnitudes than that for the non-radiative transition between the states of equal spin multiplicities.
