NMR investigations of solid (CH3)3CCOOH (trimethylacetic acid) and (CH3)3CCOOD

摘要: (CH3)3CCOOH (trimethylacetic or pivalic acid) and (CH3)3CCOOD have been investigated in the plastic brittle modifications by pulsed continuous wave proton magnetic resonance methods between 77 °K melting point (310 °K). For low‐temperature phase of (CH3)3CCOOD, second moment spin–lattice relaxation time (T1) protons are agreement with a combination methyl group (C3) t‐butyl (C3′) reorientations having activation energies (Ea) 2.35±0.15 4.00±0.25 kcal/mole, respectively. In high‐temperature above transition at 280 °K, overall molecular tumbling an Ea 6.0±0.6 kcal/mole governs T1, self‐diffusion 12±2 is evident from rotating frame (T1ρ). Also, it found that T1ρ falls significantly below T1 30° just transition. The deviation increases to as much order magnitude temperature approached, being about threefold...