Muon spin relaxation experiments were carried out on samples
of solid, pure nitrogen using conventional time-differential
transverse field (TF) techniques.
In the low temperature phase a large muonium signal
and a smaller diamagnetic muon signal together account
for virtually all the muon polarization.
In -N2 and -N2 some of the diamagnetic fraction
appears as an additional fast-relaxing signal (with initial
asymmetry and relaxation rate )
and all the asymmetries are temperature dependent.
The total asymmetry therefore has the form
The slowly-relaxing diamagnetic asymmetry and muonium asymmetry obtained are shown in Fig. 4.11. The most striking feature in the temperature dependence of these is the obvious anticorrelation between them at temperatures near T,suggesting the presence of competing processes in which the stopping muon either captures an electron to form muonium, or eventually becomes incorporated into a molecular ion. Since only half of the muonium asymmetry is experimentally observable, (the other half oscillating too fast to be resolved - see Appendix A) loss of some of the diamagnetic species to muonium formation results in an increase in the muonium asymmetry half as large. The total is nearly temperature independent. Since the free electron mobility in -N2 increases with temperature below T like the muonium fraction, this strongly suggests that transport of electrons through the lattice is involved in muonium formation in solid nitrogen. The electron mobility measured in solid nitrogen by Loveland et al. is shown in Fig. 4.12. From 63 K down to 53 K the mobility is constant at about 1.710-3 cm2s-1V-1; it then decreases gradually to half this value at T. The available mobility data below Tdoesn't reveal the trend in -N2 but it does indicate that the mobility is sharply increased to about in the phase. Over this range in T the muonium asymmetry changes by about the same fraction as the electron mobility, at least in the phase.