Use of a two-sequential radical reaction scheme to rationalise the high-oxidation-state carbene species detected under confinement conditions for the interactions Fe(5D) + CH4−n Fn (n = 2−4)

Results obtained from CASSCF–MRMP2 calculations are used to explain the carbene products observed under matrix conditions for the interactions Fe(⁵D) + CH_4–nF_n (n = 2–4) in terms of two sequential reactions involving the radical species ·FeF + CH_4–nF_n–1. For the CH₂F₂ and CHF₃ molecules, the first reaction leads to the radical fragments ·FeF + CH₂F (or ·CHF₂). As these species remain trapped in the matrix, they can recombine themselves to form the inserted complex CH₂F–Fe–F (or CHF₂–Fe–F). The carbene H₂C = FeF₂ (or HFC = FeF₂) is reached from the inserted structure by α-migration of an additional fluorine atom to the metal centre. The rebounding reactions can take place along both the quintuplet and triplet asymptotes varying only in the spin of the non-metal fragment. This model explains the triplet compound H₂C=FeF₂ detected for the interaction Fe + CH₂F₂ and allows theoretically assigning as quintuplet the complex HFC=FeF₂ observed for the reaction Fe + CHF₃.     

Chemical mechanisms in C3F8-H2 radiofrequency discharges

Discharges fed with C₃F₈-H₂ mixtures have been studied by means of mass spectrometry in a tubular reactor operated at 0.5 torr and 50 W. Comparison of the results with those obtained with emission actinometry give additional evidence that emission actinometry and mass spectrometry are powerful diagnostic tools to monitor stable and unstable species in discharges utilized for dry etching and polymer depositions. Mechanisms for end product formation and polymer deposition are also discussed.     

Effect of bias and temperature on the bulk and surface properties of gold-containing plasma-polymerized fluorocarbons

Gold-containing plasma-polymerized fluorocarbon thin films have been deposited in an RF glow discharge fed with hexafluoroethane, while a gold target was simultaneously sputtered. Tile temperatureT _s and RF-induced biasU _s of a third electrode, used as a substrate holder, were separately varied. The influence ofT _s andU _s on the plasma and file lihn characteristics were individually studied using actinometric optical emission spectroscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, and measurements of optical transmission and surface contact angles. IncreasingU _s (up to –200 V) andT _s (up to 90°C) resulted in similar effects, namely a higher degree of cross-linking, higher gold concentration, better film stability with time, and increased wettability. A key role of the energy flux of particles impinging on the growing surface has been shown to account far the experimental results.On leave from the Faculty of Mathematics and Physics, Charles University, Praha, Czechoslovakia.     

Enhancing Dual-State Emission in Maleimide Fluorophores through Fluorocarbon Functionalisation

Herein, a library of trifluoroethyl substituted aminomaleimide derivatives are reported with small size and enhanced emissions in both solution and solid-state. A diCH₂CF₃ substituted aminochloromaleimide exhibits the most efficient dual-state emission (Φ_f >50 % in solution and solid-state), with reduced quenching from protic solvents. This is attributed to the reduction of electron density on the maleimide ring and suppressed π-π stacking in the solid-state. This mechanism was explored in-depth by crystallographic analysis, and modelling of the electronic distribution of HOMO-LUMO isosurfaces and NCI plots. Hence, these dual-state dyes overcome the limitations of single-state luminescence and will serve as an important step forward for this rapidly developing nascent field.     

Design of Highly Stable Echogenic Microbubbles through Controlled Assembly of Their Hydrophobin Shell

Dispersing hydrophobin HFBII under air saturated with perfluorohexane gas limits HFBII aggregation to nanometer‐sizes. Critical basic findings include an unusual co‐adsorption effect caused by the fluorocarbon gas, a strong acceleration of HFBII adsorption at the air/water interface, the incorporation of perfluorohexane into the interfacial film, the suppression of the fluid‐to‐solid 2D phase transition exhibited by HFBII monolayers under air, and a drastic change in film elasticity of both Gibbs and Langmuir films. As a result, perfluorohexane allows the formation of homogenous populations of spherical, narrowly dispersed, exceptionally stable, and echogenic microbubbles.