Ayako Kai

Electron spin resonance of bloodstains and its application to the estimation of time after bleeding

The degradation of blood constituents in unheparinized dry blood was studied with electron spin resonance (ESR) at various temperatures. The intensity of ESR signals of methemoglobins, non-heme irons and organic radicals in dried human blood increases with time. Considering the kinetics of the signal growth, the formation mechanism of the paramagnetic species was discussed. The ESR signal (g = 4.3) of non-heme iron is usable in estimating the time after bleeding or injury using bloodstains.

Electron spin resonance of sulfite radicals in irradiated calcite and aragonite

Abstract Radiation-induced radicals in sulfite-doped calcite and aragonite were characterized by ESR. Among the many ESR signals produced, only four signals are dependent on the SO2-3 concentration; an axial signal (g⊥=2.0038 and g|=2.0024) in calcite, and an orthorhombic signal (g1=2.0042, g2=2.0038 and g3=2.0025), an isotropic signal (g=2.0034) and an isotropic signal (g=2.0060) in aragonite. The former two signals exhibit hyperfine structures arising from 33S (I= 3 2 , 0.75% natural abundance), and are attributed to SO-3 radicals. The isotropic signal at g=2.0034 in aragonite is considered to be due to rotating SO-3 radicals. Rotating or tumbling molecules (probably SO-2) produced by thermal decomposition of SO2-3 seem to be responsible for the isotropic signal at f=2.0060.

Sulfite radicals in irradiated calcite

Radiation-induced radicals in calcite doped with SO32-, SO42- or PO43- were investigated with electron spin resonance (ESR). An axially symmetric ESR signal (g⊥=2.0038 and g//=2.0024) was enhanced by doping with SO32-. We suggest that SO3- radical ions are responsible for the signal.

ESR dating of teeth, bones and eggshells excavated at a Paleolithic site of Douara Cave, Syria

Abstract Teeth, bones and eggshells excavated at a Paleolithic site, Douara Cave in Syria were measured with electron spin resonance (ESR) in their natural state without destructive sample pre-treatment. The total dose of natural radiation (TD) was estimated using the ESR signals of CO33− radicals (g⊥ = 2.0024, g∥ = 1.9977) for teeth and bones and those of radicals (g∥ = 2.0016, g⊥ = 1.9981) for eggshells. Microwave saturation behaviour and thermal annealing of eggshells are studied in detail.

ESR dating of saline sediments using NaHCO3 and NaCl

Abstract Age estimates of NaCl and NaHCO3 in the sediments at Searles Lake, California have been obtained using electron spin resonance (ESR). ESR signals are identified as H+Ca2+CO33− or H+CO2− electron type and hole CO3− type centres, stabilized by impurities in NaHCO3 and in NaCl. The total dose of natural radiation (TD) and the tentative ESR ages were determined using these signals based on U, Th and K analyses assuming uranium series disequilibrium for a simple infinite medium. Although ESR ages are concordant with the stratigraphy, radiation assessment considering the loss and incorporation of radioactive elements must be made to get reliable absolute ages.

Spatial Variation of CO2- and SO3- Radicals in Massive Coral as Environmental Indicator

Electron spin resonance (ESR) signal intensities of a massive coral colony from the Great Barrier Reef are measured-along the growth direction with a microwave scanning ESR imaging system. The annual high intensity regions of CO2- radicals are the same as the skeletal high density regions. Those of SO3- radicals are the same as the yellow-green fluorescent bands which correlate with summer. A long-range fluctuation which has a 12-year cycle is also observed in the intensities of these two radicals. Thus, the ESR signal intensities of coral can be used as an indicator of past environmental changes.

ESR dating of organic substances utilizing paramagnetic degradation products

Abstract Most biological and organic materials degrade by various reactions forming paramagnetic degradation products. We have studied the paramagnetic degradation products in dried blood and some organic materials with electron spin resonance (ESR). The intensity of ESR signals of oxidized irons with g -values of 6 and 4.3 increases, as the time increases. These signals are usable for dating ofn biological materials which initially contain hemoproteins. The error of estimated ages is mainly caused by the ambiguity in the assessment of environmental conditions, especially temperature. We propose a hybrid ESR dating method using two signals for reduction of the ambiguity in the temperature assessment.