Core excitation, decay, and fragmentation in solid benzene as studied by x-ray absorption, resonant Auger, and photon stimulated desorption

Abstract

For condensed benzene ice layers, core photoabsorption near edge structure (x-ray absorption; recorded by Auger electron yield measurements), decay electron spectra for resonant and nonresonant excitation, and fragmentation as evident in yields of hydrogen and other ions, have been measured in the C1s region. The absorption spectrum is better resolved than most previously published spectra, exhibits some new features, and shows a high degree of parallelity to the spectrum of isolated molecules. Interestingly, the hydrogen ion yield indicates a particular dissociativeness of a certain core excitation resonance, X, which in the molecule has previously been assigned to a Rydberg state. This selective dissociation suggests that the responsible excitation is strongly antibonding for the carbon–hydrogen bond, while the degenerate Rydberg states broaden into a conduction band in the solid; and that the bond breaking probably occurs or at least starts in the core-excited state, thus proceeding on an extremely short time scale, similarly to observations for other hydrogen-containing molecules. The decay spectra are analyzed in terms of autoionization vs normal Auger decay and indicate that, apart from the first strong π resonance (which leads to pure autoionization) and the X resonance, the core resonances partly or fully ionize before core decay takes place. For the X resonance, the decay spectrum contains a contribution which cannot be assigned to intact benzene; this is taken as additional evidence for ultrafast dissociation, i.e., competitive with core decay. We use these results for a discussion of the influence of condensation on excitation, decay, and fragmentation.

Low frequency noise analysis on organic thin film transistors

“…18 For RR-P3HT, the interchain-stack distance is 3.8 Å in the lamella plane but 17 Å between lamellae separated by the alkyl side chains. These stacks can be either out-of-plane ͑oop͒ stacking in which the plane of the thiophene rings are approximately perpendicular to the film plane, or in-plane ͑ip͒ stacking in which they are nearly parallel to the plane.…”

Bond polarization and image-potential screening in adsorbed C6F6 on Cu(111)

“…On Cu(1 1 1), benzene adsorbs with its aromatic ring almost parallel to the surface [11] while in the second layer, the molecules are perpendicular to the underlayer [12] leading to a 'T' geometry. But at higher coverages, the molecules are oriented randomly [13] due to weak intermolecular (van der Waals type) interaction. For C 6 F 6 , crystallinity in the solid has been reported [14].…”

Solvent Effects on Chain Orientation and Interchain π‐Interaction in Conjugated Polymer Thin Films: Direct Measurements of the Air and Substrate Interfaces by Near‐Edge X‐ray Absorption Spectroscopy

“…[27] However, smallmolecule analogues in the condensed phase, such as Th and benzene, tend to adopt a highly staggered herringbone motif in which the hydrogen atoms are disposed over the center of neighboring aromatic rings, and the C_C distance is correspondingly longer, which may explain the absence of strong p-p effects. [14,28] The calculations therefore predict that stronger p-interactions led to smaller R values. Hence rreg-P3HT chain segments at the substrate interface appeared to p-stack better than at the air interface.…”