Core electron chemical shifts in conjugated molecules and polymers

AbstractThe conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220–250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states.

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Binding energies and chemical shifts of least bound core electron excitations in cubic ANB8−N semiconductors

physica status solidi (b) ◽

10.1002/pssb.2221070227 ◽

1981 ◽

Vol 107 (2) ◽

pp. 637-651 ◽

Cited By ~ 24

Author(s):

F. Bechstedt ◽

R. Enderleln ◽

R. Wischnewski

Keyword(s):

Chemical Shifts ◽

Binding Energies ◽

Core Electron ◽

Electron Excitations

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Core electron chemical shifts of hydrogen-bonded structures

Chemical Physics Letters ◽

10.1016/j.cplett.2008.12.023 ◽

2009 ◽

Vol 468 (4-6) ◽

pp. 294-298 ◽

Cited By ~ 25

Author(s):

Guangde Tu ◽

Yaoquan Tu ◽

Olav Vahtras ◽

Hans Ågren

Keyword(s):

Chemical Shifts ◽

Core Electron ◽

Hydrogen Bonded

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X-ray photoelectron spectroscopic (XPS) studies of iodine oxocompounds

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19880425 ◽

1988 ◽

Vol 53 (3) ◽

pp. 425-432 ◽

Cited By ~ 7

Author(s):

Zdeněk Bastl ◽

Heidrun Gehlmann

Keyword(s):

Cross Sections ◽

Chemical Shifts ◽

Theoretical Data ◽

Binding Energies ◽

Oxidation States ◽

Core Electron ◽

X Ray ◽

The Core ◽

Quantitative Surface Analysis ◽

Electron Binding Energies

The core electron binding energies of eighteen compounds containing iodine in different oxidation states ranging from (-I) to (VII) have been measured. The observed chemical shifts differ from the literature data. The anticipated existence of hexavalent iodine in certain compounds has not been demonstrated. The relative subshell photoemission intensities of iodine have been determined. Empirically derived atomic sensitivity factors and theoretical photoionization cross-sections have been used to calculate the surface stoichiometry. The concentration ratios obtained via the two methods are compared. In agreement with generally accepted view the results of this comparison imply that, for quantitative surface analysis, empirical values should be used rather than theoretical data.

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