Shear Stress Effect on the Absorption Spectra of Organic Thin Films Under High Pressure.

The effects of shear stress on the absorption spectra of a thin film of one-dimensional bis(diphenylglyoximato)platinum(II), Pt(dpg) 2 have been studied under high pressure. The color of the thin film turns from red-brown at ambient pressure to green at 0.4 GPa. Then, one sapphire anvil is rotated by applied force in order to generate shear stress at 0.4 GPa. The color of the thin film at the outer part on the anvil changes remarkably from green to yellow, but the color at the center is green. The absorption spectra of Pt(dpg) 2 have simultaneously been measured under shear deformation and non-hydrostatic conditions. The absorption intensity of the visible band decreases sharply at outer part, and this absorption peak abruptly shifts to the near-infrared region. The powder x-ray diffraction profiles of the thin film of Pt(dpg) 2 at center and outer parts have been studied under shear deformation. The 110 and 200 lines at outer part markedly shift to the lower d-value region. In contrast, both diffraction lines at the center part are insensitive to shear stress. This behavior corresponds to the shift of the absorption band at outer part. [ABSTRACT FROM AUTHOR]