INFRARED PHOTOREFRACTIVE COMPOSITES BASED ON POLYIMIDE AND J-AGGREGATES OF CYANINE DYE

Photorefractive composites sensitive to 1064 nm on a base of an aromatic polyimide containing J-aggregates of a thiacarbocyanine dye are presented. The molecules of the dye form the nanocrystalline J-aggregates that are responsible for photoelectric sensitivity at 1064 nm and nonlinear third-order optical properties. The net gain coefficient 266 cm-1 and the response time 0.09 s were achieved at an external electric field of about 15 V/μm.

Das lichtelektrische Verhalten des Kaliums im festen und flüssigen Zustand

Massive potassium -layers are deposited by evaporation in ultrahigh vacuum upon a glasssubstrate. The photoelectric sensitivity of these very pure layers, which are polycrystalline, liquid or monocrystalline (solidified from melt), is measured in the spectral range from 380 nm to the threshold wavelength. From this the work function is determined by the Fowler-theory. The adaptation of the experimental points to the theoretical Fowler-curve succeed also in the short wave region of the spectrum, if the photoelectric sensitivity is referred to the light energy absorbed within the exit dephts of photoelectrons. The Fowler equation is also available to the liquid phase. At the phase-change liquid-solid and solid (solidified)-liquid, respectively, no measurable alteration of the work function am ounting to 2.30 ± 0.02 eV occurs. A significantly higher work function of 2.39 ± 0.01 eV, however, is obtained on polycrystalline potassiumlayers. consisting of (110)-planes. The quantum yields and the quantity constant of about 2.3 · 10-11 electrons/(photon degree2) calculated from the Fowler-equation do not show any discontinuity at the melting point. Within the measuring accuracy they are also independent of the crystalline constitution of the potassium.