Abstract
We have developed a new sapphire-anvil cell to generate shear stress at high pressures. The new cell is similar to a diamond-anvil cell. Bis(diphenylglyoximato)metal(II), M(dpg)2(M = Ni and Pt) are pressure-sensitive one-dimensional metal complexes. By use of this cell we have observed in situ the shear stress effect on a thin film of M(dpg)2 under the microscope. Furthermore, electronic absorption spectra of both complexes have been simultaneously measured under applied shear deformation and non-hydrostatic conditions. When the pressure is increased, the color of a thin film of Pt(dpg)2 turns from red-brown at ambient pressure to green at 0.4 GPa. One sapphire anvil is rotated by applied force in order to generate the shear stress at 0.4 GPa. The color of the thin film changes remarkably from green to yellow at the outer part on the anvil, but the color at the center is green, insensitive to the shear stress. The region changed by the shear stress can be observed with the naked eye. Absorption spectra of the yellow region at the outer part change markedly; the intensity of the d-p band decreases sharply and this peak abruptly shifts to the near-infrared region. On the other hand, electronic spectra at the center part are insensitive to the shear deformation. The similar shear stress effect on the optical spectrum of Ni(dpg)2 is also observed. We have found that electronic states of M(dpg)2 essentially change by applying shear deformation.
(Contributed by Hiroo INOKUCHI, M. J. A., Nov. 12, 2003)
