Pressure dependence of wall relaxation in polarized 3He gaseous cells

We have observed a linear pressure dependence of longitudinal relaxation time ${T}_{1}$ at 4.2 and 295 K in gaseous $^{3}\mathrm{He}$ cells made of either bare Pyrex glass or Cs- or Rb-coated Pyrex due to paramagnetic sites in the cell wall. The paramagnetic wall relaxation is previously thought to be independent of $^{3}\mathrm{He}$ pressure. We develop a model to interpret the observed wall relaxation by taking into account the diffusion process, and our model gives a good description of the data.