Optical properties, layered double

A. Bolognesi, C. Botta, and L. Cecchinato, Optical properties and electroluminescence of poly(3-alkylmethoxy-thiophene) single- and double-layer structures, Synth. Met., 111-112 187-189, 2000. 

Further improvement of the structural and optical properties of the PLD Bragg mirrors was achieved by substituting ZnO by yttria stabilized zir-conia (YSZ, with typically 9 at. % Y2O3), as demonstrated in Fig. 7.29. A considerable increase of the maximum reflectivity of the Bragg structures from about 90-99% was realized by doubling the number of YSZ-MgO layer pairs from 5.5 to 10.5 as shown in Fig. 7.29 (top). The experimentally obtained single layer thicknesses of the 5.5 and 10.5 pair structure are given in the caption and show smaller variation compared to the MgO-ZnO structure of Fig. 7.28. Indeed, the SNMS isotope intensity depth profile... 

What are the capacitances, resistances, optical properties, chemical compositions and electronic structures of the hydroxide films as the function of potential and of the electric double layer at che OCP ... 

Figure 13 shows the optical properties of a typical copolymer 34e (PMA-DSB-PBD) and its electroluminescence in a double layer device using PPV as hole-injection layer. The device has good shelf stability and an internal quantum efficiency (0.04%). It begins to emit blue light (475 nm) at a forward bias potential of 17 V (Figure 14). 

Electrochemical-SPR measurements have been used to characterize structural and optical properties involving the analysis of biosensors. The simultaneous approach is logical since both methods are—from an instrumental point of view— highly complementary and have found widespread applications in different research domains, including studies of the electrochemical double layer, the investigation of the electrochemical doping process, as well as electrical field enhanced studies [5, 6]. 

Bewick and Tuxford " have used ac electromodulation reflectance spectroscopy with square wave modulation (stair case) from a potential in the double-layer range to various potentials in the anodic film range. They report the detection of film formation already at Eu = 0.7 V and that the signal associated with the film formation increases until 1.5 V where it levels off. They conclude that the general features of the wavelength dependence of the reflectance spectrum are determined primarily by the wavelength dependence of the optical properties of the Pt substrate and not by the film. 

We have not studied all types of colloidal systems in detail but limited ourselves to suspensions, siufac-tants, emulsions and foams. In terms of properties, the stability and associated concepts (double layer, van der Waals forces, steric effects) as well as the DLVO theory have been presented in detail, while kinetic and especially the optical properties have been discussed more briefly. 

A five-period InGaN/GaN multiple quantum well (MQW) was fabricated on this high-quality GaN hornoepitaxial layer. The XRD profile of the MQW consisted of satellite peaks, where the evaluated well and barrier layer thicknesses were 3.4 and 11.3 nm, respectively. It is noteworthy that the growth rates of InGaN and GaN derived from the well and barrier thicknesses are comparable with those on the (0001) plane. As for the optical properties, we were interested in if the short radiative lifetime observed for the microfacet QWs was preserved. Therefore, TRPL measurements were conducted at 10 K. The excitation pulses were from a frequency-doubled Ti sapphire laser with a wavelength of 380 nm to selectively excite InGaN wells and a power density as low as 470 nj cm. The PL was detected by a streak camera. Figure 14.15... 

In many problems it is necessary to know either the number of particles (flocculation phenomena) or their total surface (double layer problems) or their size and shape (optical properties) ... 

As we have pointed out already, an entity at the surface or in the electrochemical double layer in submonolayer amounts is readily picked up by reflectance spectroscopy only when it is either strongly absorbing (e.g., a dye molecule) or strongly interacting with the substrate (i.e., chemisorbed). In the latter case, the species is then optically detected either as an adsorbate-induced perturbation of the substrate s optical constants or because the interaction with the substrate changes the electronic (and hence optical) properties of the adsorbed species in such a way that it becomes absorptive, even if this species is nonabsorbing in solution (surface complex, surface compound). 

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