Synchrotron-radiated X-ray and neutron diffraction study of native cellulose

Precise determination of d-spacings and compositional ratio of cellulose I-alpha and I-beta in various native cellulose samples was successfully carried out by synchrotron-radiated X-ray diffraction and time-of-flight (TOF) neutron diffraction from quasi-powder specimens. X-ray diffraction peaks were separated by the deconvolution method using sig types of profile function: Gaussian, Lorentzian, intermediate Lorentzian, modified Lorentzian, pseudo-Voigt, and Pearson VII. In terms of R-factors, the pseudo-Voigt function gave the best fit with the observation, and was used for determination of d-spacings. The numerical results for Valonia cellulose were: dI(alpha) (100) = 0.613 nm; dI(beta) (1 (1) over bar 0) = 0.603 nm; dI(beta) (1 (1) over bar 0)= 0.535 nm; dI(alpha) (0 1 0)= 0.529 nm; I-alpha content = 0.65. The differences determined between dI(alpha) (1 0 0) and dI(beta) (1 (1) over bar 0) and between dI(beta) (1 1 0) and dI(alpha) (0 1 0) were similar to those previously reported. Comparison between unresolved peaks for the two types of cellulose samples revealed a small but definite difference between dI(alpha) (1 1 0) and dI(beta) (2 0 0). The TOF neutron diffractometry using deuterated samples confirmed this difference.