Direct Probing of Vibrational Interactions in UiO-66 Polycrystalline Membranes with Femtosecond Two-Dimensional Infrared Spectroscopy

[Image: see text] UiO-66 is a benchmark metal–organic framework that holds great promise for the design of new functional materials. In this work, we perform two-dimensional infrared measurements on polycrystalline membranes of UiO-66 grown on c-sapphire substrates. We study the symmetric and antisymmetric stretch vibrations of the carboxylate groups of the terephthalate linker ions and find that these vibrations show a rapid energy exchange and a collective vibrational relaxation with a time constant of 1.3 ps. We also find that the symmetric vibration of the carboxylate group is strongly coupled to a vibration of the aromatic ring of the terephthalate ion. We observe that the antisymmetric carboxylate vibrations of different terephthalate linkers show rapid resonant (Förster) energy transfer with a time constant of ∼1 ps

Extreme ultraviolet photoelectron spectroscopy on fluorinated monolayers: Towards nanolithography on monolayers

The semiconductor industry plans to keep fabricating integrated circuits, progressively decreasing there features size, by employing extreme ultraviolet lithography (EUVL). With this method, new designs and concepts for photoresist materials need to be conceived. In this work, we explore an alternative concept to the classic photoresist material by using an organic self-assembled monolayer (SAM) on a gold substrate. The monolayer, composed of a richly fluorinated thiol sensitive to low-energy electrons, is adsorbed on the Au substrate which acts as main EUV-absorber and as the source of photoelectrons and secondary electrons. We investigate the stability of the SAM adsorbed on gold towards EUV radiation by means of in-situ photoelectron spectroscopy. The photoelectron spectra indicate that the monolayer attenuates a significant amount of primary electrons generated in the gold layer. The spectral evolution upon EUV irradiation indicates that the SAM loses a significant amount of its initial fluorine content (ca. 40% at 200 mJ/cm2). We attribute these chemical changes mostly to the interaction with the electrons generated in the thiol/Au system

Enhanced Grain-boundary Emission Lifetime and Additive Induced Crystal Orientation in One-Step Spin-Coated Mixed Cationic (FA/MA) Lead Perovskite Thin Films Stabilized by Zinc Iodide Doping

Mixed cationic lead perovskites containing formamidinium and methylammonium can be stabilized by incorporating ZnI2 as an “internal desiccant”. Next to prolonged stability under ambient conditions we show with XRD that the use of an additive, 3-chloropropyl ammonium chloride, influences crystal formation by orienting the crystals. These ~500 nm crystals show individual photoluminescent behavior in thin films and have a longer photoluminescence lifetime at the grain boundaries as compared to the center of the crystal or relative to un-doped materials without the additive made under identical conditions. Charges recombine slower at the edges of the crystals as observed with confocal laser scanning microscopy. The material can also be prepared as a black precursor powder by a solid-solid reaction under ambient conditions