Measurement of Mean Life of Cadmium 2^3p1 by Thermal Motion of Excited Atoms during Life Time

Since the experiments of Dunoyer in 1914 some interest has developed in an experiment to show the diffusion of excited atoms in various types of resonance lamps. None of these have been successful due to the short life time of the excited states in the vapors selected. Since experiments made in this laboratory indicate a long life for the Cadmium 23P1 state, an attempt was made to measure the life of this state by the motion of the excited atoms in a unidirectional beam shot from a gun of the boiler type, and excited by passing through a narrow beam of light from a Cadmium discharge. The resonance radiation was photographed, a shield hiding the part of the beam in which the atoms were being excited from the camera. Radiation was observed above the shield edge. Below the shield - the edge near the gun - no radiation was observed indicating that the effect above was not due to secondary resonance. The results indicate a mean life for the Cadmium 23P1 state in excess of 10-6 seconds