文摘
A new method that can chemically discriminate thevisually indistinguishable sapwood from heartwood indiscolored woods is presented in this paper. Discriminating between sapwood and heartwood, which are normallyrecognized by color in cross sections of stems of tress, isimportant in dendrochronological dating, as well as inevaluating qualities of woods such as durability. In tree-ring chronology, the felling date, which affects the construction date of architectures, can be estimated only inwoods that have a recognizable sapwood/heartwood boundary. However, the felling date cannot be estimated indiscolored woods because it has indistinguishable sapwood. Time-of-flight secondary ion mass spectrometry(TOF-SIMS) analysis of specific chemical substancesretained for approximately 1300 years after felling demonstrated the presence of sapwood in a discolored ancientarchitectural wood of Hinoki cypress (Chamaecyparisobtusa). Direct molecular mapping by TOF-SIMS clearlyindicated that the specific substances, hinokinin, hinokiresinol, hinokione, and hinokiol, started to accumulate at the sapwood/heartwood boundary where onlyhinokinin was localized and retained predominantly in rayparenchyma cells. The result allowed the determinationof the felling date of the discolored wood. TOF-SIMS hasshown to be useful for investigating the distribution ofminute amounts of chemical components in woods.