EUROISMAR 2019

Recently, the function of proteins is much more attract attention and measurement of high-pressure NMR about proteins showed many remarkable results in this field. We reported zero-field splitting (ZFS) parameter D term was increased depending on load pressure raise that used the hemin as a model compound of metalloprotein using ESR employing terahertz light and high–pressure (HP–THz ESR). On the other hand, g_z value was shown significant decreases in especially almost 0 to 1 GPa region, inversely. However, calibration of pressure in this system is not enough and estimated pressure value from the outer load is conceiving with containing some volume of errors. Because due to the pressure standard marker like as DPPH as magnet field marker was not reported. Hence, we considered that the ability and usability of Tutton's salt (TS) as a pressure standard marker. TS could understand from simple crystal field theory and precise ZFS parameters of various TS could be got from recent reports of Prof. Rudowicz group. A TS with Fe²⁺ ion (also called Mohr's salt, S=2) was measured in the region of up to 1.8 GPa and 0.4 THz. The result showed significant pressure dependence of E term (H//y) as increase of E = 3.7782 (0 GPa) to E = 4.8345 (1.8 GPa). This increase of E term had assigned from the decrease of symmetry of orthorhombic crystal structure depending pressure rise. Especially, referencing similar study without pressure, increase of E term conclude as decrease of symmetry along x- and y-axis direction. Similarly, we also evaluated TS salt containing with Ni²⁺ ion (S=1). In the presentation of the day, we will show the result in detail.