The electron spin resonance (ESR) detects unpaired electrons, which are trapped and stabilized at lattice defects and impurities in substances. The number of trapped electrons is increased by natural and artificial irradiation of ionizing radiation. In a magnetic field, the unpaired electrons are raised to the excited state by absorbing the microwave energy. The absorbed energy is equivalent to the number of trapped electrons and thus to the radiation dose accumulated over the observed period.
The JEOL FA-100 X-band electron spin resonance (ESR) spectrometer was installed at LIAG, equipped with a variable temperature controller (ES-DVT4) for low-temperature measurements from the room temperature to 103 K. An in-house device for sample irradiation using a Varian VF-50J X-ray tube with the maximum energy of 50 kV and an integrated heating element (100—600°C) has been developed for artificial irradiations and preheats for samples within quartz glass tubes (Oppermann & Tsukamoto, 2015). This device is used to conduct single aliquot equivalent dose (De) measurements (Tsukamoto et al., 2015; 2017). An ESR age is derived by dividing the De by the environmental dose rate for the sample.
Since ESR dating method was introduced to earth sciences in the mid-1970s, it has been applied to a wide range of substances. Calcium carbonate such as mollusc shells, corals or speleothems as well as tooth enamel were successfully dated. Another datable material is quartz. We are currently focusing on the quartz ESR dating for dating sediments, because ESR has a great potential to extend the age range of the luminescence dating. We are also developing the method of ESR thermochronology (King et al., 2016) using quartz to investigate mountain uplift/erosion and fault activity.
Investigating the Deep Roots of Human Behaviour Details
(the Arts and Humanities Research Council project led by Professor Larry Barham (University of Liverpool)
Constraining the role of erosion in feedbacks between tectonics and climate: Quaternary evolution of the Japanese Alps Details
(Swiss National Foundation Ambizione Project by Dr. Georgina King)
Trapped-charge thermochronometry and thermometry: A status review. Chemical Geology, 466, 3 – 17.
2016 KING, G.E., GURALNIK, B., VALLA P.G. & HERMAN, F.
A portable system of X-ray irradiation and heating for electron spin resonance (ESR) dating. Ancient TL, 33, 11 – 15.
2015 OPPERMANN, F. & TSUKAMOTO, S.
Dose recovery and residual dose of quartz ESR signals using modern sediments: Implications for single aliquot ESR dating. Radiation Measurements
in press TSUKAMOTO, S., PORAT, N. & ANKJÆRGAARD, C.
Single aliquot regenerative dose method for ESR dating using X-ray irradiation and preheat. Radiation Measurements, 81, 9 – 15.
2015 TSUKAMOTO, S., TOYODA, S., TANI, A. & OPPERMANN, F.