<i>K</i>-edge near-edge x-ray-absorption fine structure of oxygen- and carbon-containing molecules in the gas phase

Sham, Tsun‐Kong; Yang, Bingxin; Kirz, Janos; Tse, John S.

doi:10.1103/physreva.40.652

Cited by 108 publications

(92 citation statements)

References 72 publications

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“…Furthermore, the functional and other subgroups in such large compositions are regarded as independent units. But each of these units has its ionization point at another energy, as known from the literature (Francis and Hitchcock 1992;Hitchcock 1987, 1988;Sham et al 1989;Stöhr 1992;Kikuma and Tonner 1996). Thus, due to a mix of chemistries leading to chemical shifts of the core level, the arctangent for large and complex molecules like environmental samples would be very broad, and thereby dominate the fit of the spectra and submerging the Gaussian curves, see Fig.…”

Section: Analysis Of the Spectramentioning

confidence: 99%

“…However, as seen from NEXAFS spectra of small, well-understood molecules Hitchcock 1987, 1988;Sham et al 1989;Cooney and Urquhart 2004;Kolczewski et al 2006;Bâldea et al 2007;Solomon et al 2009), shifts of peak positions and absorption edges occur, depending on, e.g., the chemical environment, the substrate, or the state of aggregation. Furthermore, the functional and other subgroups in such large compositions are regarded as independent units.…”

Section: Analysis Of the Spectramentioning

confidence: 99%

“…At first, NEXAFS was used to characterize small, wellknown molecules (Francis and Hitchcock 1992;Ishii and Hitchcock 1987, 1988, Sham et al 1989, Stöhr 1992 and their orientation and bond lengths. Soon, more complex samples from polymer science were investigated using NEXAFS spectroscopy, see for example Kikuma and Tonner (1996); Urquhart and Ade (2002).…”

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confidence: 99%

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Characterization of refractory organic substances by NEXAFS using a compact X-ray source

et al. 2011

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Purpose We present the characterization of environmental samples using near-edge X-ray absorption fine structure (NEXAFS) spectra recorded with an in-house device. We want to point out the feasibility of such an easily accessed complementary technique, if not sometimes alternative to NEXAFS studies performed with synchrotron radiation, as the number of compact setups is increasing. Materials and methods The experiments were carried out using a laser-driven plasma source. We studied heterogeneous samples like refractory organic substances to demonstrate the potential of NEXAFS spectra, achieved by such an instrument, concerning specimens of high chemical complexity.Results and discussion From the respective resonance peaks in the spectra, the presence of certain functional groups, such as aromatic or carbonyl groups, is verified, and the elemental composition is estimated. The results of the reference samples are consistent with the literature. For the environmental samples, external influences of the extraction solvent or fertilizers can be determined from the spectra. Conclusions This could provide the possibility to perform test experiments with samples, which are later studied in more detail with synchrotron light and might as well give an impulse on the broader spread of the application of NEXAFS spectroscopy.

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Section: Analysis Of the Spectramentioning

confidence: 99%

Section: Analysis Of the Spectramentioning

confidence: 99%

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Characterization of refractory organic substances by NEXAFS using a compact X-ray source

et al. 2011

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“…Ionization energies for OCS are 540.3 eV for O 1s [18], 295.5 eV for C 1s [19], and 170.3 and 171.6 eV for S 2p 3=2 and 2p 1=2 , respectively [19]. About 7.2 eV below the O 1s threshold lies the O 1s !…”

Section: P H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 99%

Nearest-Neighbor-Atom Core-Hole Transfer in Isolated Molecules

et al. 2004

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A new phenomenon sensitive only to next-door-neighbor atoms in isolated molecules is demonstrated using angle-resolved photoemission of site-selective core electrons. Evidence for this interatomic coreto-core electron interaction is observable only by measuring nondipolar angular distributions of photoelectrons. In essence, the phenomenon acts as a very fine atomic-scale sensor of nearest-neighbor elemental identity. DOI: 10.1103/PhysRevLett.92.223002 PACS numbers: 33.60.Fy, 33.80.Eh For decades, photoelectron spectroscopy (PES) has been an established method for probing the electronic and chemical structure of matter in both gaseous and condensed phases [1]. Coupled with a tunable light source, such as synchrotron radiation, PES is often done resonantly; e.g., direct photoemission intensity from an outer (valence) orbital or energy level is modified in a narrow wavelength range by interference with resonant excitation of an electron in a deeper-lying (core) orbital. Recently, a new phenomenon, multiatom resonant photoemission (MARPE), was reported in condensed phase MnO [2 -4] in which the core-level photoemission intensity, or cross section, from one element (O) is enhanced upon resonant excitation of a core electron from a different element (Mn) in the solid. The unprecedented core-to-core interaction represented by MARPE is explained as a collective resonant effect from several nearby atoms and has been proposed as a new tool for identifying near-neighbor atoms (within 2 nm) in solids. Reports of MARPE have engendered both interest and skepticism in the photoemission community [5,6]. From an isolated-molecule point of view, MARPE is an unusual form of resonant-Auger decay and can be understood as an interatomic coupling between direct core-electron photoemission from one atom and resonant core-electron excitation of a different atom in the same molecule. Up to now, attempts to find experimental evidence for this MARPE-like effect in small gas-phase molecules by looking for variations in photoemission intensities, whether integrated (cross sections) or differential (angular-distribution parameters), have been in vain.In this Letter we report the first evidence of an interatomic coupling effect in molecular photoemission solely involving core levels. To distinguish it from the relatively longer-range MARPE effect, the inherently short-range (i.e., nearest-neighbor-only) effect in isolated molecules will be referred to as nearest-neighbor-atom core-hole transfer, or NACHT. While solid-state MARPE affects photoemission cross sections, no such intensity variations are observable in the molecular analog; the NACHTeffect is measurable only in the differential cross section, which describes the angular distributions of photoelectrons and is sensitive to the phases of the photoelectrons' continuum wave functions, as well as their magnitudes. Moreover, it is necessary to consider differential-cross-section effects beyond the usual dipole approximation (DA) for interactions between radiation and matter. The electri...

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“…For example, shifts in peak position were used to discern between oxidized black carbon and organic matter adsorbed to black carbon surfaces Liang et al, 2006). Energy calibration is, for example, done using CO 2 for carbon [with characteristic π*, 3 s, and 3 p peaks at 290.7, 292.74, and 294.96 eV, respectively (Sham et al, 1989;Ma et al, 1991)] and oxygen [with characteristic π* and 3 s peaks at 535.0 and 539.3 eV, respectively (Sham et al, 1989), and 535.4 and 539.0 eV ], using N 2 for nitrogen [with a characteristic 1 s → π*(v = 1) peak (second large peak) at 401.10 eV (Sodhi and Brion 1984)], using variscite [2149 eV (Beauchemin et al, 2003)] for phosphorus, and elemental sulfur [2872 eV (Hutchison et al, 2001;Solomon et al, 2003)] or calcium sulfate (2482.5 eV) for sulfur NEXAFS. Careful measurement of standard substances, explicit mentioning of the energy position to which a standard was calibrated is essential to working with and reporting NEXAFS results.…”

Section: Quantification Of Bonds and Compoundsmentioning

confidence: 99%

Synchrotron‐Based Near‐Edge X‐Ray Spectroscopy of Natural Organic Matter in Soils and Sediments

Lehmann

Solomon

Brandes

et al. 2009

Biophysico‐Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems

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SyNCHROTRON-BASED NEAR-EDgE X-RAy SPECTROSCOPy discrete radii indexed by a principal quantum number n = 1,2,3 …, and discrete binding energies for single-electron atoms of E n = −E 0 Z 2 /n 2 , where Z is the atomic number and E 0 = 13.6 eV (see Figure 17.1). When the energy of incident photons is increased to match the binding energy of an electron, the photon absorption probability suddenly increases in what is called an X-ray absorption edge (step function in Figure 17.2, which is at about 290 eV for carbon), so that the electron is completely removed from the atom in an ionization event (absorption edges are also labeled figure 17.1. Atom in the Bohr model. The electrons surround the nucleus. An incoming photon can lift an electron to a not fully occupied, higher orbital or remove it entirely from the atom. Energy (eV)280 285 290 295 300 Normalized absorption Measured ModeledStep functionfigure 17.2. Carbon NEXAFS spectrum of NOM from the Suwannee River (IHSS standard humic acid mounted on indium foil; total electron yield using a dwell time of 200 msec and an exit slit of 50 µm, calibrated to CO at 287.38 eV, Canadian Light Source SgM beamline 11-ID.1) to show pre-edge features and the so-called "edge". The spectrum is deconvoluted using a series of gaussian curves (g) at energy positions of known transitions, along with a step function at the edge as described by .

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K-edge near-edge x-ray-absorption fine structure of oxygen- and carbon-containing molecules in the gas phase

Cited by 108 publications

References 72 publications

Characterization of refractory organic substances by NEXAFS using a compact X-ray source

Characterization of refractory organic substances by NEXAFS using a compact X-ray source

Nearest-Neighbor-Atom Core-Hole Transfer in Isolated Molecules

Synchrotron‐Based Near‐Edge X‐Ray Spectroscopy of Natural Organic Matter in Soils and Sediments

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