Assembly and decomposition of building blocks to analyze polymer NEXAFS spectra

Pettersson, Lars; Ågren, Hans; Schürmann, Britta L.; Lippitz, Andreas; Unger, Wolfgang

doi:10.1002/(sici)1097-461x(1997)63:3<749::aid-qua16>3.3.co;2-o

Cited by 18 publications

(24 citation statements)

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“…However, as already observed in previous investigations on NEXAFS spectra of substituted benzene molecules, [16][17][18][19] the excitations at the C atom directly connected to the substituent are the only ones that show a remarkable chemical shift. For the other C atoms belonging to the phenyl ring, only limited energy shifts with 2͒ and calculated C 1s NEXAFS spectra of glycine, phenylalanine, histidine, tyrosine, and tryptophan.…”

Section: B Phenylalaninesupporting

confidence: 60%

A theoretical study of the near-edge x-ray absorption spectra of some larger amino acids

Carravetta¹,

Plashkevych

Ågren

1998

The Journal of Chemical Physics

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Section: B Phenylalaninesupporting

confidence: 60%

A theoretical study of the near-edge x-ray absorption spectra of some larger amino acids

Carravetta¹,

Plashkevych

Ågren

1998

The Journal of Chemical Physics

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“…25,61,62 A theoretical study of Mn K edge NEXAFS based on TDDTF by Jaszewski et al 25 proposes a "low" Mn oxidation state evolution, where the Mn 4 ator gauge invariance in a full basis set, which leads to "good quality" oscillator strengths also for limited basis sets -a major advantage for property calculations using TD methods. However, for core excitations the situation is completely different, something that follows from two neglected effects in TD methods: lack of orbital relaxation, which breaks the final state rule for NEXAFS, 63 and, in the case of DFT, the electron self-interaction error, which is very large for core electrons.…”

Section: Nexafs K Edge Spectra Of Models Of the Mn 4 Complexmentioning

confidence: 99%

“…It is now possible to correlate specific X-ray features with functional groups and even individual bonds, such that the total spectrum can be considered as a linear combination of elementary spectra -the "building block principle". [1][2][3][4][5] In addition to applications of this principle and other thumb rules, the general development in simulation technology has made it possible to address ever larger systems with complex X-ray spectra, such as biological molecules. Thus, computational studies of the near edge X-ray absorption fine structure (NEXAFS) spectra of amino acids and polypeptides in solution or on surfaces have become common practice.…”

Section: Introductionmentioning

confidence: 99%

Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II

2012

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The Mn 1s Near Edge Absorption Fine Structure (NEXAFS) has been computed by means of transition potential gradient corrected Density Functional Theory (DFT) on four Mn 4 Ca clusters modeling the successive S 0 to S 3 steps of the oxygen evolving complex (OEC) in photosystem II (PSII). The model clusters were obtained from a previous theoretical study where they were determined by energy minimization. They are composed of Mn(III) and Mn(IV) atoms, progressing from Mn(III) 3 Mn(IV) for S 0 , to Mn(III) 2 Mn(IV) 2 for S 1 , to Mn(III)Mn(IV) 3 for S 2 , and to * To whom correspondence should be addressed † Uppsala University ‡ Stockholm University ¶ Royal Institute of Technology 1 Mn(IV) 4 for S 3 , implying an Mn centered oxidation during each step of the photosynthetic oxygen evolution. The DFT simulations of the Mn 1s absorption edge reproduce the experimentally measured curves quite well. Using the half-height method, the theoretical IPE's are shifted by 0.93 eV for the S 0 to S 1 transition, by 1.43 eV for the S 1 to S 2 transition, and by 0.63 eV for the S 2 to S 3 transition. The IPE shifts depend strongly on the method used to determine them, and the most interesting result is that the present clusters reproduce the shift in the S 2 to S 3 transition obtained both with the half-height and with the second derivative methods, thus giving strong support to the previously suggested structures and assignments.

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“…Considering that the near-edge fine structure can provide a "fingerprint" for several types of chemical bonding or of functional groups (e. g. π* and σ* bonding in C containing materials), the building-block principle (BBP) was established as one approach to interpret the ELNES in terms of LDOS [14]. Direct comparison with spectra from known standards is often all that is required for conclusive identification of the bonding state, i.e., it is not necessary to model the LDOS of these complex materials to be able to interpret the ELNES and NEXAFS spectra.…”

Section: Introductionmentioning

confidence: 99%

Chemical Bonding in Low-k Dielectric Materials for Interconnect Isolation: Characterization using XAS and EELS

Schmeißer¹

2006

AIP Conference Proceedings

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In chemical vapor deposited (CVD) organosilicate glasses (OSG), which are used as interlayer dielectric (ILD) materials, the substitution of oxygen in SiO 2 by methyl groups (-CH 3 ) reduces the permittivity significantly. However, plasma processing for resist stripping, trench etching and post-etch cleaning removes C and H containing molecular groups from the nearsurface layer of OSG. Therefore, compositional analysis and chemical bonding characterization of structured ILD films with nanometer resolution is necessary for process optimization. OSG thin films as-deposited and after plasma treatment are studied using X-ray absorption spectroscopy (XAS) and electron energy loss spectroscopy (EELS). In both techniques, the fine structure near the C-K absorption or energy loss edge, respectively, allows to differentiate between C-H, C-C, and C-O bonds, and consequently, between individual low-k materials and their modifications. Examination of the C-K near-edge structures reveal a modified bonding of the remaining C atoms in the plasma-treated sample regions.

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Assembly and decomposition of building blocks to analyze polymer NEXAFS spectra

Cited by 18 publications

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A theoretical study of the near-edge x-ray absorption spectra of some larger amino acids

A theoretical study of the near-edge x-ray absorption spectra of some larger amino acids

Modeling Near-Edge Fine Structure X-ray Spectra of the Manganese Catalytic Site for Water Oxidation in Photosystem II

Chemical Bonding in Low-k Dielectric Materials for Interconnect Isolation: Characterization using XAS and EELS

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