Inelastic Decay of Electrons in the Shockley-type Metal-Organic Interface States

We present a theoretical study of lifetimes of interface states (IS) on metal-organic interfaces PTCDA/Ag(111), NTCDA/Ag(111), PFP/Ag(111), and PTCDA/Ag(100), describing and explaining the recent experimental data. By means of unfolding the band structure of one of the interfaces under study onto the Ag(111) Brillouin zone we demonstrate, that the Brillouin zone folding upon organic monolayer deposition plays a minor role in the phase space for electron decay, and hence weakly affects the resulting lifetimes. The presence of the unoccupied molecular states below the IS gives a small contribution to the IS decay rate mostly determined by the change of the phase space of bulk states upon the energy shift of the IS. The calculated lifetimes follow the experimentally observed trends. In particular, we explain the trend of the unusual increase of the IS lifetimes with rising temperature.Comment: 8 pages, 5 figure

Analysis of the Flow Behaviors of Corn Meal during Extrusion

Food extrusion can be used to make many products we consume today, including pasta, cereals and more. The ability to predict the characteristics of the final product from an extruder using raw material characteristics and operating conditions is vital to the extrusion process. In order to answer this need, the flow behavior of corn meal was measured in a lab viscometer (off-line) and compared to the flow behaviors from an extruder (in-line) at three different moisture contents (32.5%, 35%, 37.5% wet basis). The extruder and product are heated through the friction of the corn meal passing through the barrel not external heaters. Feed rate, RPM, and moisture content are the inputs considered to compare the die temperatures, shear rates, and shear stresses. Behaviors of extruder outputs based on RPMs, moisture contents, and feed rates have been recorded and compared. A method called super-positioning was used to compare the off-line and in-line data. Previous results have been not conclusive. Our methodology can be used to take lab results and predict extruder flow behaviors. The results can also be used in predicting operating conditions for various sizes of extruders. The super-positioning methodology will be able to be applied to other extruders and advance a flow model for the current extruder

Beam lead technology

Beam lead technology for microcircuit interconnections with applications to metallization, passivation, and bondin

Quantum Rotor Engines

This chapter presents autonomous quantum engines that generate work in the form of directed motion for a rotor. We first formulate a prototypical clock-driven model in a time-dependent framework and demonstrate how it can be translated into an autonomous engine with the introduction of a planar rotor degree of freedom. The rotor plays both the roles of internal engine clock and of work repository. Using the example of a single-qubit piston engine, the thermodynamic performance is then reviewed. We evaluate the extractable work in terms of ergotropy, the kinetic energy associated to net directed rotation, as well as the intrinsic work based on the exerted torque under autonomous operation; and we compare them with the actual energy output to an external dissipative load. The chapter closes with a quantum-classical comparison of the engine's dynamics. For the single-qubit piston example, we propose two alternative representations of the qubit in an entirely classical framework: (i) a coin flip model and (ii) a classical magnet moment, showing subtle differences between the quantum and classical descriptions.Comment: Chapter of the upcoming book "Thermodynamics in the Quantum Regime - Recent Progress and Outlook

Book Reviews

Reviews of the following books: The Lobster Coast: Rebels, Rusticators, and the Struggle for Forgotten Frontier by Colin Woodard; Writing on Stone: Scenes from a Maine Island Life by Christina Marsden Gillis; photographs by Peter Ralston and Forward by Philip Conkling; Owascoag, Black Poynt, Mayne: History of Black Point (Scarborough) Maine, ca. 1600-1800: A Narrative by Patricia Bowden Corey; Continental Liar from the State of Maine: James G. Blaine by Neil Rolde; No Flies on Bill : The Story of an Uncontrollable Old Woman, My Grandmother, Ethel Billie Gammon by Darcy Wakefield; An Upriver Passamaquoddy by Allan J. Sockabasin; Rug Hooking in Maine, 1838 - 1940 by Mildred Cole Peladea

Click chemistry in ultra-high vacuum - tetrazine coupling with methyl enol ether covalently linked to Si(001)

The additive-free tetrazine/enol ether click reaction was performed in ultra-high vacuum (UHV) with an enol ether group covalently linked to a silicon surface: Dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate molecules were coupled to the enol ether group of a functionalized cyclooctyne which was adsorbed on the silicon (001) surface via the strained triple bond of cyclooctyne. The reaction was observed at a surface temperature of 380 K by means of X-ray photoelectron spectroscopy (XPS). No indications for tetrazine molecules which bind directly to the Si(001) surface via the nitrogen atoms were detected. A moderate energy barrier was deduced for this click reaction in vacuum by means of density functional theory based calculations, in good agreement with the experimental results. This UHV-compatible click reaction thus opens a new, flexible route for synthesizing covalently bound organic architectures

Relevance of π-Backbonding for the Reactivity of Electrophilic Anions [B12X11]− (X=F, Cl, Br, I, CN)

Electrophilic anions of type [B12X11]− posses a vacant positive boron binding site within the anion. In a comparatitve experimental and theoretical study, the reactivity of [B12X11]− with X=F, Cl, Br, I, CN is characterized towards different nucleophiles: (i) noble gases (NGs) as σ-donors and (ii) CO/N2 as σ-donor-π-acceptors. Temperature-dependent formation of [B12X11NG]− indicates the enthalpy order (X=CN)>(X=Cl)≈(X=Br)>(X=I)≈(X=F) almost independent of the NG in good agreement with calculated trends. The observed order is explained by an interplay of the electron deficiency of the vacant boron site in [B12X11]− and steric effects. The binding of CO and N2 to [B12X11]− is significantly stronger. The B3LYP 0 K attachment enthapies follow the order (X=F)>(X=CN)>(X=Cl)>(X=Br)>(X=I), in contrast to the NG series. The bonding motifs of [B12X11CO]− and [B12X11N2]− were characterized using cryogenic ion trap vibrational spectroscopy by focusing on the CO and N2 stretching frequencies (Formula presented.) and (Formula presented.), respectively. Observed shifts of (Formula presented.) and (Formula presented.) are explained by an interplay between electrostatic effects (blue shift), due to the positive partial charge, and by π-backdonation (red shift). Energy decomposition analysis and analysis of natural orbitals for chemical valence support all conclusions based on the experimental results. This establishes a rational understanding of [B12X11]− reactivety dependent on the substituent X and provides first systematic data on π-backdonation from delocalized σ-electron systems of closo-borate anions. © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH Gmb

Feasibility tests of transmission x-ray photoelectron emission microscopy of wet samples

We performed feasibility tests of photoelectron emission spectromicroscopy of wet samples in the water window (285-532 eV) soft x-ray spectral region. Water was successfully confined in an ultrahigh vacuum compatible compartment with x-ray transparent sides. This water cell was placed in the MEPHISTO spectromicroscope in a transmission geometry, and complete x-ray absorption spectra of the water window region were acquired. We also show micrographs of test samples, mounted outside of the compartment, and imaged through the water. This technique can be used to study liquid chemistry and, at least to the micron level, the microstructure of wet samples. Possibilities include cells in water or buffer, proteins in solution, oils of tribological interest, liquid crystals, and other samples not presently accessible to the powerful x-ray photoelectron emission spectromicroscopy technique

Synthesis of a rhodium(III) dinitrogen complex using a calix[4]arene-based diphosphine ligand

The synthesis and characterisation of the rhodium(III) dinitrogen complex [Rh(2,2’-biphenyl)(CxP2)(N2)]+ are described, where CxP2 is a trans-spanning calix[4]arene-based diphosphine and the dinitrogen ligand is projected into the cavity of the macrocycle