Optical properties of azo (EO) chromophore (DR1) doped in poly amic acid (PAM)
In this work, we studied the effects of annealing on the structural and optical properties of an azo electro optic (EO) polymer, Disperse Red1 (DR1), doped in Poly Amic Acid (PAM). Thin films were deposited on glass substrates by spin coating technique. The films were annealed at 195°C. The Structural and optical properties of the doped films were investigated by using UV-VIS spectra, Atomic Force Microscopy (AFM) and Prism Coupling technique. The number of modes, angles of coupling, thickness and refractive index were compared before and after annealing. The experimental results, showed 24nm blue shift in the photon absorption peak and number of modes and surface roughness of thin films decreased after annealing. Thickness was reduced about 1um and refractive index was increased by 0.03.
Degradation study on structural and optical properties of annealed Rhodamine B doped poly(vinyl) alcohol films
Abstract We report the observations on optical and structural properties of thermally treated undoped and doped poly(vinyl) alcohol (PVA) films as a function of doping and annealing temperature. The crystalline peaks of both PVA and Rhodamine B are seen in the X-ray diffraction (XRD) of the as prepared samples where the crystallinity of Rhodamine B increases with doping. At 2 wt% doping, Rhodamine B crystals segregate and are seen at the surface. However, after annealing only PVA peaks remain and Rhodamine B becomes amorphous as seen from XRD and micro-Raman measurements. It is shown how the thermal energy imparted to host PVA and dopant Rhodamine B molecules results in the movement of molecules, breaking the bonds inside the material. The intensity and frequency of Raman active modes is observed to be modified with increasing temperature due to structural changes in polymer bonds. It is also observed that thermal annealing leads to a shift in the optical absorption edge towards lower energies. This is attributed to the modified electronic states. The overall results are interpreted in terms of modifications in structural and optical properties.
NMR characteristics of intracellular K in the rat salivary gland: a 39K NMR study using double-quantum filtering.
Intracellular K of the perfused rat mandibular salivary gland was measured by 39K NMR spectroscopy at 8.45 T. Multiple-quantum NMR arising from multiple-exponential decay was used to eliminate the resonance due to extracellular K in the perfused gland at 25 degrees C. The resonance due to intracellular K consisted of two Lorentzian signals stemming from the [spin 1/2 to -1/2] coherence (sharp resonance) and the [spin -1/2 to -3/2], [spin 3/2 to 1/2] coherences (broad resonance). The transverse relaxation time (T2) corresponding to the [spin 1/2 to -1/2] coherence was ca. 2.5 ms, and that corresponding to the [spin -1/2 to -3/2], [spin 3/2 to 1/2] coherences was ca. 0.4 ms. The relaxation time of the double-quantum coherence of rank 3 (originating from product operators like Ix2Iz) was determined to be ca. 0.2 ms. These results suggest the possibility of the presence of a single homogeneous population of intracellular K with a correlation time of ca. 2.5 x 10(-8) s and a quadrupolar coupling constant of ca. 1.4 MHz.