THERMOLUMINESCENCE, PHOTOLUMINESCENCE AND OPTICAL-ABSORPTION OF AURAMINE-O UNDER HIGH-PRESSURE

The effect of pressure has been measured on the thermoluminescence, photoluminescence and optical absorption of auramine O both in the crystalline state and dispersed in poly (acrylic acid). The methods used were sensitive to distinct changes in environment and structure of auramine O. In general, in crystalline samples two discontinuous changes were observed. The first discontinuity is seen in the pressure region 0-3 kbar in the photoluminescence and absorption spectra. The second one is mainly seen in the thermoluminescence as a decrease of trap energy for charge carriers. The origin of the discontinuities is discussed in the framework of the relative perturbation of different excited states by pressure as well as of pressure induced structural transformations. Auramine O dispersed in polymer, in contrast to crystalline samples, exhibited only monotonic changes under pressure using any of the three spectroscopies.