The -RA Verb Form in Spain

Rosenberg, S. L. Millard; Wright, Leavitt O.

doi:10.2307/470022

Cited by 2 publications

(3 citation statements)

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“…67,68 Correlating experimental measurements of energy barriers to photoemission with new and evolving theoretical models that account for these variables will be critical to develop a foundational understanding of phenomena responsible for spin-selective transmission, ionization, and chiral-selective chemistries. 69,70…”

Section: Discussionmentioning

confidence: 99%

Spin-Dependent Ionization of Chiral Molecular Films

et al. 2019

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Spin selectivity in photoemission from ferromagnetic substrates functionalized with chiral organic films was analyzed by ultraviolet photoelectron spectroscopy at room temperature. Using radiation with photon energy greater than the ionization potential of the adsorbed molecules, photoelectrons were collected that originated from both underlying ferromagnetic substrates and the organic films, with kinetic energies in the range of ca. 0-18 eV. We investigated chiral organic films composed of self-assembled monolayers of α-helical peptides and electrostatically adsorbed films of the protein, bovine serum albumin, with different α-helix and β-sheet content. Ultraviolet photoelectron spectral widths were found to depend on substrate magnetization orientation and polarization, which we attribute to helicity-dependent molecular ionization cross sections by photoelectron impact, possibly resulting in spin-polarized holes. These interactions between spinpolarized photoelectrons and chiral molecules are physically manifested as differences in the measured photoionization energies of the chiral molecular films. Substrate magnetizationdependent ionization energies and work function values were deconvoluted using surface charge neutralization techniques, permitting the measurement of relative spin-dependent energy barriers to transmission through chiral organic films.

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Section: Discussionmentioning

confidence: 99%

Spin-Dependent Ionization of Chiral Molecular Films

et al. 2019

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“…44 This strong spin polarization was attributed to the higher density and more uniform orientation of helical molecules in films compared to dilute molecular vapors. 45,46 Importantly, asymmetric scattering probabilities have been shown to depend on electron kinetic energies; the de Broglie wavelength of photoelectrons must be commensurate with the length of the molecular helices, 47 suggesting lower likelihood of spin selectivity in photoemission for low kinetic energy electrons transmitted through short DNA strands (i.e., one to two helical turns). However, incorporation of high-Z species into the helical framework should enhance the scattering rate via relativistic effects, thus amplifying asymmetry induced by the chiral environment.…”

Section: -43mentioning

confidence: 99%

“…This was expected, considering that these DNA hairpins were composed of only 12 hybridized bases (Figure 2a), and therefore likely support too few helical turns to allow for detectable spin-selective effects. 44,47 The measured values of I for SAMs of 1MM with and without Hg 2+ are presented in Figure 3f. Differences in ionization energy between 0MM and 1MM samples were attributed to nucleobase substitution; adenine has a lower ionization energy than thymine, in DNA.…”

Section: -43mentioning

confidence: 99%

Differential Charging in Photoemission from Mercurated DNA Monolayers on Ferromagnetic Films

et al. 2020

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Spin-dependent and enantioselective electron-molecule scattering occurs in photoelectron transmission through chiral molecular films. This spin selectivity leads to electron spin filtering by molecular helices, with increasing magnitude, concomitant with increasing numbers of helical turns. Using ultraviolet photoelectron spectroscopy, we measured spin-selective surface charging accompanying photoemission from ferromagnetic substrates functionalized with monolayers of mercurated DNA hairpins that constitute only one helical turn. Mercury ions bind specifically at thymine-thymine mismatches within self-hybridized single-stranded DNA, enabling precise control over the number and position of Hg 2+ along the helical axis. Differential charging of the organic layers, manifested as substrate magnetization-dependent photoionization energies, was observed for DNA hairpins containing Hg 2+ ; no differences were measured for hairpin monolayers in the absence of Hg 2+ . Inversion of the DNA helical secondary structure at increased metal loading led to complementary inversion in spin selectivity. We attribute these results to increased scattering probabilities from relativistic enhancement of spin-orbit interactions in mercurated DNA.

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The -RA Verb Form in Spain

Cited by 2 publications

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Spin-Dependent Ionization of Chiral Molecular Films

Spin-Dependent Ionization of Chiral Molecular Films

Differential Charging in Photoemission from Mercurated DNA Monolayers on Ferromagnetic Films

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