Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Single-electron wavefunctions, or orbitals, are the mathematical constructs used to describe the multi-electron wavefunction of molecules. Because the highest-lying orbitals are responsible for chemical properties, they are of particular interest. To observe these orbitals change as bonds are formed and broken is to observe the essence of chemistry. Yet single orbitals are difficult to observe experimentally, and until now, this has been impossible on the timescale of chemical reactions. Here we demonstrate that the full three-dimensional structure of a single orbital can be imaged by a seemingly unlikely technique, using high harmonics generated from intense femtosecond laser pulses focused on aligned molecules. Applying this approach to a series of molecular alignments, we accomplish a tomographic reconstruction of the highest occupied molecular orbital of N2. The method also allows us to follow the attosecond dynamics of an electron wave packet.

Tomographic imaging of molecular orbitals

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

The replacement of hydrogen atoms with fluorine substituents in organic substrates is of great interest in synthetic chemistry because of the strong electronegativity of fluorine and relatively small steric footprint of fluorine atoms. Many sources of nucleophilic fluorine are available for the derivatization of organic molecules under acidic, basic, and neutral conditions. However, electrophilic fluorination has historically required molecular fluorine, whose notorious toxicity and explosive tendencies limit its application in research. The necessity for an electrophilic fluorination reagent that is safe, stable, highly reactive, and amenable to industrial production as an alternative to very hazardous molecular fluorine was the inspiration for the discovery of selectfluor. This reagent is not only one of the most reactive electrophilic fluorinating reagents available, but it is also safe, nontoxic, and easy to handle. In this Review we document the many applications of selectfluor and discuss possible mechanistic pathways for its reaction.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/anie.200400648

Selectfluor: mechanistic insight and applications.

Photoemission spectroscopy is commonly applied to study the band structure of solids by measuring the kinetic energy versus angular distribution of the photoemitted electrons. Here, we apply this experimental technique to characterize discrete orbitals of large π-conjugated molecules. By measuring the photoemission intensity from a constant initial-state energy over a hemispherical region, we generate reciprocal space maps of the emitting orbital density. We demonstrate that the real-space electron distribution of molecular orbitals in both a crystalline pentacene film and a chemisorbed p-sexiphenyl monolayer can be obtained from a simple Fourier transform of the measurement data. The results are in good agreement with density functional calculations.

https://physik.uni-graz.at/~pep/Publications/Puschnig2009a.pdf

Reconstruction of molecular orbital densities from photoemission data.

The spherically averaged electron density distribution of the highest occupied molecular orbital (HOMO) for the amino acid glycine has been determined by multichannel electron momentum spectroscopy. Comparison of the measured HOMO electron momentum distribution with near-Hartree-Fock limit and density functional theory (DFT) calculations for the Boltzmann-weighted sum of the eight predicted stable conformers indicates that electron correlation effects must be included in order to adequately reproduce the experimental results for glycine. The best-fitting DFT calculation determined with the Becke-Perdew gradient-corrected exchange-correlation functional was used to generate HOMO electron density maps for oriented glycine conformers. The result is shown for the most stable conformer.

https://science.sciencemag.org/content/sci/270/5237/786.full.pdf

Imaging the electron density in the highest occupied molecular orbital of glycine

Experimental momentum profiles (orbital images) corresponding to the electron density distribution in the outer valence shell of gaseous glycine have been obtained by electron momentum spectroscopy measurements conducted over the binding energy range of 6−27 eV at an impact energy of 1200 eV + binding energy. The experimental data are compared with theoretical momentum profiles calculated using Hartree−Fock and Kohn−Sham density functional theories. The calculated momentum profiles correspond to a Boltzmann weighted sum of the five dominant conformers predicted to be present at the experimental temperature of 165 °C. The importance of basis set size and flexibility is investigated in the case of the Hartree−Fock results by performing calculations using a series of basis sets ranging from minimal (STO-3G) to the near-Hartree−Fock limit (aug-cc-pVTZ). The sensitivity of the density functional theory calculations to the type of exchange-correlation potential energy functional is investigated by comparing res...

Glycine Valence Orbital Electron Densities: Comparison of Electron Momentum Spectroscopy Experiments with Hartree−Fock and Density Functional Theories

Imaging of orbital electron densities by electron momentum spectroscopy – a chemical interpretation of the binary (e,2e) reaction

Unexpected and previously unexplained behaviour showing appreciable intensity at low momenta in previously published binary (e, 2e) cross sections for ionization from atomic orbitals including Xe 4d, Zn 3d and Cd 4d is investigated. Similar effects have also been observed recently in binary (e, 2e) studies of metal hexacarbonyls for the least tightly bound molecular orbitals which are dominated by metal character. The finite cross sections at low momenta (i.e. non-nodal behaviour) are not predicted by plane-wave calculations for atomic targets, but can be accounted for using distorted-wave theory. These distortion effects at low momenta appear to be due to a high- effect and the even-parity nature of atomic orbitals.

https://iopscience.iop.org/article/10.1088/0953-4075/31/5/003/pdf

Distorted-wave effects at low momentum in binary (e, 2e) cross sections for d-orbital ionization

The differential scattering cross sections and the generalized oscillator strengths of the 1${\mathrm{}}^{1}$S\ensuremath{\rightarrow}2${\mathrm{}}^{1}$S and 1${\mathrm{}}^{1}$S\ensuremath{\rightarrow}2${\mathrm{}}^{1}$P transitions of helium have been measured by angle-resolved electron-energy-loss spectroscopy with an incident electron energy of 1500 eV and within the range 2\ifmmode^\circ\else\textdegree\fi{}--11.5\ifmmode^\circ\else\textdegree\fi{} of scattering angles. The corrections for angular factors and density effects have also been made for the experimental results. The differential cross sections and generalized oscillator strength values are absolute and are the first to be measured at such a high impact energy. The experimental results are compared with other measurements and theoretical calculations in the literature. \textcopyright{} 1996 The American Physical Society.

Y. Zheng

Papers

Imaging the electron density in the highest occupied molecular orbital of glycine

Glycine Valence Orbital Electron Densities: Comparison of Electron Momentum Spectroscopy Experiments with Hartree−Fock and Density Functional Theories

Imaging of orbital electron densities by electron momentum spectroscopy – a chemical interpretation of the binary (e,2e) reaction

Distorted-wave effects at low momentum in binary (e, 2e) cross sections for d-orbital ionization

Absolute generalized oscillator strengths of 2 1 S and 2 1 P excitations of helium measured by angle-resolved electron-energy-loss spectroscopy