A study of water exchange in wood by means of 2D NMR relaxation correlation and exchange

Two-dimensional T-1-T-2 H-1 NMR relaxation correlation spectra and T-2-T-2 relaxation exchange spectra for samples of spruce wood across the full moisture content range from 0% to > 100% are presented. The T-1-T-2 spectra unambiguously identify water in different environments within the wood that overlap in the corresponding and more traditional one-dimensional T-1 or T-2 experiment. The T-2-T-2 spectra unambiguously reveal the presence of water exchange between the lumen and cell wall above the fibre saturation point in sapwood. An estimate is made of the exchange rate: 1/30 to 1/3 ms(-1).