ABSTRACT
AH and / are the linewidth and intensity of the ESR signal) and from a cali bration sample of l,l-diphenyl-2-picrylhydrazyl (DPPH), yielding the curves for the temperature-dependent susceptibility \(T ) shown in Fig. 36 [69]. All insu lating fibers exhibit an increase in \CO with decreasing T at low temperatures and a constant x at high temperatures. On the other hand, the C6 6F does not exhibit any temperature dependence of the susceptibility, indicating contribu tions only from the conduction electrons, which exhibit a Pauli temperature dependence of the susceptibility
where p# and p ^ ) are the Bohr magneton and the density of states at the Fermi level, respectively. On the other hand, the insulating CXF fibers in Fig. 36 have contributions to xCO from both conduction electrons [equation (31)] and local ized electrons. These localized electrons exhibit a Curie law temperature de pendence of the susceptibility:
Table 4 Various ESR Characterization Parameters for CXF Fibers
x in CXF 6.6 4.5 3.8 3.6 3.1 Ro (kU/o)a 0.7 74.7 403 895 1853 X r t (10-8 emu g_1)a 1.1 1.22 1.24 1.31 1.85 a (1CT8 emu g_1)b 1.10 1.12 1.12 1.13 1.72 0 (10-8 emu • K g’1)” -0 17.8 32.0 34.3 42.1 N/C ( X 10 4)c -0 0.97 1.62 1.77 2.27 Pfir (p-U • m)a 0.64 41 215 476 1000 Stage 2 1 1 1 1
9.096 5.521 5.295 5.32 5.535 xps A d a ; 9.95 4.88 3.81 3.45 2.87 S (|xm)f 4.15 33.2 76.1 113.2 164.2 AHPP (G f 1.5 1.5 2.0 1.05 1.5 T2 (ns)h 44 44 33 60 44 T, (ns)h — 0.64 — 1.15 Source: Ref. 69. aThe in-plane resistivity p*r, sheet resistance RD, and magnetic susceptibility Xrt are all at 300 K. bThe parameters a and 0 describe the magnetic susceptibility according to Eq. (34). CN is the number of localized spins per C atom. d/ c is the c-axis repeat distance for the intercalation compound. cA c/Af is the the XPS ratio of line intensities of carbon to fluorine. f8 is the skin depth for the microwave signal in the ESR experiment. 8AHpp is the linewidth of the ESR signal. hTx and T2 are, respectively, the spin-lattice and spin-spin relaxation times.
