Electron Momentum Spectroscopy and Its Applications to Molecules of Biological Interest

Abstract

Articles you may be interested inKinetic processes in supercooled monosaccharides upon melting: Application of dielectric spectroscopy in the mutarotation studies of D-ribose Dissociation of the ground state vinoxy radical and its photolytic precursor chloroacetaldehyde: Electronic nonadiabaticity and the suppression of the H+ketene channel Theoretical investigation of the eight low-lying electronic states of the cis-and trans-nitric oxide dimers and its isomerization using multiconfigurational second-order perturbation theory (CASPT2) Abstract. Energy and wave function are the heart and soul of Schrodinger quantum mechanics. Electron momentum spectroscopy (EMS) so far provides the most stringent test for quantum mechanical models (theory, basis sets and the combination of both) through observables such as binding energy spectra and Dyson orbital momentum distributions. The capability of EMS to measure Dyson orbitals of a molecule as momentum distributions provides a unique opportunity to assess the models of quantum mechanics based on orbitals, rather than on energy dominated (mostly isotropic) properties. Recently, the author introduced a technique called dual space analysis (DSA), which is based on EMS and quantum mechanics to analyze orbital based information in the more familiar position space as well as the less familiar momentum space.In this article, the development of EMS and DSA is reviewed through the applications to molecules of biological interest such as amino acids, nucleic acid bases and recently nucleosides. The emphasis is the applications of DSA to study isomerization processes and chemical bonding mechanisms of these molecules.Keywords: Electron momentum spectroscopy, density functional theory calculations, binding energy spectra, orbital momentum distributions, dual space analysis, atoms in molecules, conformers and tautomers. PACS:31.15.Fx, 31.25.Qmand36.20Kd is the insight into the structure of genetic material, e.g., DNA, at molecular level. Shape (structure) determines whether the atoms that can form bonds to the atoms of another molecule are in close proximity of each other. Properties of related fragments and molecules, such as DNA/RNA fragments CP963, Vol.

Experimental and Theoretical Electron Momentum Spectroscopic Study of the Valence Electronic Structure of Tetrahydrofuran under Pseudorotation

“…[19][20][21][22][23][24][25][26][27] Previous studies have established that EMS is an attractive technique to investigate conformations of organic molecules and small biomolecules. [17][18][19][20][21][28][29][30][31][32][33] It has been demonstrated that the symmetries of the HOMOs with respect to the minimal structures of C s and C 2 on the potential-energy surface (PES) produced by pseudorotation differentiate the conformers of THF. 17 detailed theoretical analysis of the individual valence orbitals of the three important structures, C s , C 2 , and C 1 produced by pseudorotation of THF.…”

Simulating ionization spectra for small biomolecules in inner and valence shells

“…Theoretically, calculations far from trivial are necessary to accurately reveal inner-shell properties and simple models are usually unable to reveal the subtle differences caused by various chemical environment and conformation of biomolecules. For example, tautomers of DNA bases [2,5,7] exhibit only minor differences in energy, but reveal significant configurational changes in the core shell [16,17]. This paper reports recent applications in simulating ionization spectroscopy including synchrotron sourced X-ray spectroscopy and electron momentum spectroscopy (EMS) to study both core and valence structures for biomolecules.Fully optimized geometries are obtained using density functional theory (DFT) B3LYP/aug-cc-pVTZ or B3LYP/6-311G** models incorporated in Gaussian03 [18], followed by vibrational analysis to ensure minimum energy structures.…”