Luminescence spectroscopy of matrix-isolated atomic cadmium

Abstract

The luminescence spectroscopy of atomic cadmium isolated in the solid rare gases is recorded using pulsed synchrotron radiation excitation of the 5p 1P1←5s 1S0 resonance transition. Steady-state and time-resolved analysis of the ultraviolet (UV) emission bands recorded in the Cd/Ne, Cd/Ar, and Cd/Kr systems allows identification of the associated 227.3, 233.4, and the 241/262 nm bands to the singlet fluorescence of atomic cadmium. The origin of the pair of singlet emission bands at 241 and 262 nm in the Cd/Kr system is ascribed to the coexistence of two nondegenerate minima on the 5p 1T1u surface. The weak band present in the Cd/Kr system at 326 nm and the intense pair at 324.4 and 329.6 nm in Cd/Xe all have decay times longer than 1 μs and are associated with the triplet transitions of atomic cadmium. Line shape analysis of the near-UV emission pair in Cd/Xe allows a tentative assignment of the narrow 329.6 nm band to the 5p 3P0→5s 1S0 transition. The intensity of the triplet state emission was observed to be enhanced in the heavier rare gases, being completely absent in Ne and Ar, weak in Kr, and the only emission observed in Xe. The efficiency of intersystem crossing in the Cd/RG systems is very similar to that exhibited by the Zn/RG matrix systems. However, the presence of the 5p 3P0→5s 1S0 emission in Cd/Xe resembles the Hg/RG matrix systems, a reflection of the larger spin-orbit splitting in atomic cadmium compared with zinc.