Spin-lattice relaxation in liquid phosphorus tribromide

Abstract

The 31P spin-lattice relaxation time has been measured at 9 Mhz and 18 Mhz in liquid PBr3 as a function of temperature from -80°c to +180°c. The relaxation time T 1ρ in the rotating frame has also been measured from -80°c to room temperature at a Larmor frequency of 14·3 Mhz and a rotating field strength of 5·4 gauss. The 31P spin-lattice relaxation time is controlled by the spin-rotation interaction at high temperatures and a scalar interaction with the bromine at low temperatures which endows T 1 with a frequency dependence. Both a maximum and a minimum in T 1 are found at 9 Mhz. The relaxation time T 1ρ is controlled entirely by the scalar interaction over the whole temperature range. From the results we have separated the contributions to T 1 as a function of temperature from the three relaxing mechanisms, the direct dipolar, the spin-rotation and the scalar interaction and their corresponding correlation times. The correlation time for the scalar interaction is the bromine spin-lattice relaxation tim...