Untersuchungen von Relaxationserscheinungen an Quecksilberatomen im metastabilen 6³ P ₂-Zustand mit einem Impulsverfahren

Abstract

The decay of rf signalsδm=±1 between the Zeeman sublevels of mercury atoms in the metastable 6³ P ₂ state was investigated by means of a sampling method. The density matrix of the state was expanded in terms of irreducible tensor operators. By solving the appropriate differential equations, we were able to show that the time constant of the decay obtained from the measurements is the relaxation time for the longitudinal component of the mean electric quadrupole moment (alignment) of the metastable atoms. The linewidths of the rf resonances reflect the relaxation rates of the transverse components however. From the decay time, the cross sectionσ ₀=(1,80±0,11) · 10⁻¹⁴ cm² for depolarizing collisions between metastable mercury atoms (even isotopes) and ground state atoms was derived. A comparison ofσ ₀ with the value which was previously determined from the linewidths of rf resonances, indicates that the relaxation process in a weak magnetic field is essentially isotropic.