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We study the emission properties of a high quality monolithic microcavity with an embedded ultrathin organic tetrakis(4-methoxyphenyl)porphyrin layer. Spectral and angle-resolved photoluminescence measurements show a well defined polarized doublet at detection angles larger than 15°. The splitting energy ranges up to 70 meV. The usual employed mechanism, based on the mismatch between the center of the mirror stop band and the wavelength of the microcavity, accounts only for a small fraction of the observed splitting. A transfer matrix model taking into account the optical anisotropy of the organic layer, has been employed to reproduce the observed experimental results. The anisotropy of the organic layer, confirmed by optical absorption spectroscopy, origins from a local molecular order as inferred by atomic force microscopy measurements. [ABSTRACT FROM AUTHOR]

Sodium intercalated manganese thiophosphate Na0.62Mn0.69PS3 powders have been synthesized by a two-step ion-exchange process. Dielectric measurements have been performed as a function of both temperature and frequency on the prepared samples in the 20–106 Hz frequency range over the 78–350 K temperature range by using the autobalancing bridge method. The temperature dependence of the dielectric constant imaginary part reveals the presence of a loss peak at the low temperatures together with a strong dispersion at the low frequencies and at the highest investigated temperatures. While the loss peak presence is characteristic for dipolar polarization processes, the strong low frequency dispersion at not very high temperatures, observed also in the dielectric constant real part, is typical for system with hopping charge carriers. A hypothesis about the nature of such carriers has been formulated on the basis of both the ion-exchange intercalation process and the comparison with the dielectric spectra previously observed for cesium intercalated manganese thiophosphate Cs0.46Mn0.77PS3 compounds. [ABSTRACT FROM AUTHOR]

Cesium ions have been intercalated by ion exchange into layered manganese thiophosphate to produce Cs2xMn1-xPS3. Investigations have been conducted by x-ray diffraction analysis, IR absorption spectroscopy, x-ray photoemission spectroscopy (XPS), and dielectric spectroscopy. The XPS spectra, recorded at room temperature and at the Mn, P, and S 2p, Mn 3p, and Cs 3d and 4d core-level regions, indicate that no charge transfer occurs from guest species (Cs+) to pure host lattice (MnPS3). The presence of shake-up satellites at the Mn 2p and 3p core levels suggests that the cesium intercalation does not alter the nature of the Mn–S bond which is mostly ionic. Dielectric measurements, carried out between 260 and 375 K and in the 20 Hz–1 MHz frequency range, classify Cs2xMn1-xPS3 as hopping charge carrier systems. The nature of such carriers can be hypothesized on the basis of both the intercalation process by cationic substitution and the comparison with the observed dielectric response of the pure MnPS3. [ABSTRACT FROM AUTHOR]

We have prepared novel nanohybrid Li2xMn1−xPS3/GO films consisting of graphene oxide (GO) and exfoliated MnPS3nanosheets via an easy mixing protocol at room temperature. These films were investigated by SEM and AFM, as well as XRD, Raman and XPS spectroscopies, obtaining information about the nature of the interaction between MnPS3and GO. In particular, the dark colour of the nanocomposite film and, more to the point, the analysis of (i) the C1s core level XPS spectra, (ii) the interlayer spacing obtained by XRD measurements and (iii) the increment in the intensity ratio ID/IGof the two bands typical of the carbon region of GO Raman spectra, suggest that a partial reduction of GO can be obtained right upon intercalation into Li2xMn1−xPS3. [ABSTRACT FROM PUBLISHER]

Kinetics of the growth of TPPS4 porphyrin J-aggregates slow down in the order H2SO4 ＞ HCl ＞ HBr ＞ HNO3 ＞ HClO4, in agreement with the Hofmeister series. The rate constants and the extent of chirality correlate with the structure-making or breaking abilities of the different anions with respect to the hydrogen bonding network of the solvent. [ABSTRACT FROM AUTHOR]

Li2xMn1-xPS3films have been synthesized by exfoliating MnPS3through the successive intercalations of K+and Li+ions. Their dielectric response has been measured from 80 to 350 K in the frequency range of (102–106) Hz. The obtained data have been analyzed in terms of both complex permittivityε*and theacconductivityσac. The frequency dependence ofσachas been interpreted in terms of the Jonscher’s law, whose exponentndecreases by increasing temperature. Thenvalues lie between 0.479 and 0.501 and are typical of materials in which theacconductivity is due to multiple hops of carriers. By analyzing theσdctemperature dependence, the observed dielectric response has been attributed to the intercalated lithium ions, and the Li2xMn1-xPS3films have been classified ashoppingcharge carrier systems. [ABSTRACT FROM AUTHOR]

A light emitting structure consisting of two coupled microcavities has been realized and studied. One of the two cavities contains a luminescent organic thin film of tetrakis(4-methoxyphenyl)porphyrin, whereas the other microcavity is a dielectric structure coupled to the organic one by means of a LiF/ZnS Bragg mirror. Reflectivity spectra show the presence of two well defined cavity dips. We observe an energy splitting of the two cavity modes. Despite the fact that only one cavity contains the active layer, the photoluminescence spectra display two peaks with comparable intensities at the same energy of the reflectivity dips. These observations indicate the strong coupling of the two cavities. The comparison of the diagonalized effective Hamiltonian with the observed resonances further confirms the strong coupling. [ABSTRACT FROM AUTHOR]