Oriented thin films of layered perovskite compounds (RNH3)2PbI4, which possess a quantum well structure where a two-dimensional semiconductor layer of PbI4 and an organic ammonium layer of RNH3 are alternately piled up, were found to grow in a self-organizing manner on fused quartz substrates through the simple dual-source vapor deposition of organic ammonium iodide RNH3I and lead iodide PbI2. The perovskite quantum-well films showed strong exciton absorption at around 2.4 eV and sharp exciton emission even at room temperature. Further, the X ray diffraction measurement on the vacuum-deposited films demonstrated that the layer structure of the vacuum-deposited film was oriented parallel to the film plane.

We analyze in the four-generation model the first measurement of the branching ratio of rare kaon decay K + → π + νν, along with the other processes of

463A modified interference model is presented, which relates the direct channel resonance amplitude with the crossed channel Regge pole amplitude. Analyses are made in rcN scattering processes by using this model and then we discuss the relation between the resonance limplitude and background (Regge pole) amplitude in order to clarify the concept of" duality". § l. Introduction It has recently been discussed that a direct channel amplitude and its crossed channel amplitude are not independent but provide two complementary descriptions of a scattering process. 1 > This discussion on the duality concept has been brought about by the investigation of the validity of the interference model. Since the successful analyses of the interference effects in the backward rc-p differential cross section and the difference between total rc-p and rc+ p cross sections by Barger and others, 2 > it has been pursued to explain vadous scattering processes in terms of this model. But Chiu and Stirling 3 ) have shown that there are difficulties in fitting the data of the average of the total n-p and n+p cross section, the n+ p differential cross section and n+ p polarization, although this model is compatible with some other processes.The unified understanding of all cases of nN scattering processes on the basis of the interference model has been disturbed not only on account of nonuniqueness of the quantitative description of the n-p 180° differential cross section but also on account of the larger and constructive contribution of the resonance amplitude in most cases in which the interference model is imcompatible with the experimental results. In particular this model conflicts with the finite energy sum rule on the average of the n±p scattering amplitudes at e = 0, because the imaginary parts of their resonance amplitudes do not oscillate around the background Regge amplitude and always contribute constructively to the background amplitudes.Furthermore the formal suggestion by Schmid 4 ) indicates that the Regge amplitude contains in itself resonance effects, that is to say, the partial wave projection of p-Regge amplitude produces resonance loops on the Argand diagram, and such a loop corresponds to N* resonance, Then it has finally been con-by guest on March 22, 2015 http://ptp.oxfordjournals.org/ Downloaded from

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