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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 117 (2002), S. 3961-3971 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We used the energy-selected-photoelectron photoion coincidence (ESPEPICO) method to study site-specific fragmentation caused by C:1s photoionization of 1,1,1-trifluoro-2-propanol-d1 [CF3CD(OH)CH3, TFIP-d1] on a Si(100) surface. High-resolution electron energy loss spectroscopy showed that TFIP-d1 is dissociatively chemisorbed like (CF3)(CH3)CDO–Si(100), and different chemical shifts at the three carbon sites were observed by photoelectron spectroscopy. The site-specific fragmentation evident in the ESPEPICO spectra of the sub-monolayer at room temperature indicates that the TFIP-d1 there has an O–Si bond oriented in the trans position with respect to the C–CF3 bond. Here we discuss the fragmentation processes in light of the results obtained with the ESPEPICO method and the Auger-electron photoion coincidence method. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Site-specific fragmentation following Si:2p photoexcitation of (trifluorosilyl) (trimethylsilyl)methane [F3SiCH2Si(CH3)3 (FSMSM)] has been studied by means of photoelectron-photoion and photoion–photoion coincidence techniques. The total photoionization efficiency curve of FSMSM has only one broad peak near the Si:2p core-ionization threshold and no evidence is obtained for the occurrence of selective excitation of each of the two Si atoms. From the results of ab initio calculations of FSMSM, it is found that the magnitude of the Coulomb interaction between the valence electrons and the Si:2p core electrons is very similar at the two Si sites. As a result, the difference in the chemical shift of the 2p core level between the two Si sites is very small. However, the evidence for site-specific fragmentation of the molecule following the Si:2p core-level photoexcitation is obtained by analyzing the photoion–photoion coincidence spectra; the relative yields of H+–SiF+ and CH+n–SiF+3 (n=1–3) ion pairs are enhanced around 104.5 eV, and those of CH+3–F3SiCH2Si(CH3)+2, CH+3–SiCH3F+2, CH+3–Si(CH3)2F+, and H+–SiCH+3 are enhanced around 107 eV. These two thresholds are interpreted to correspond to the 2p core-level photoexcitation at the Si atom bonded to three F atoms and that at the Si atom bonded to three CH3 groups. Ionic fragmentation following excitation of these core electrons occurs selectively around the Si atom where the photoexcitation has taken place. The site-specific fragmentation scheme can be explained on the basis of the valence electron density around the excitation site. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 10751-10755 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We used photoelectron spectroscopy and the energy-selected-photoelectron photoion coincidence method to study site-specific fragmentation following Si:2p photoionization of 1-trifluorosilyl-2-trimethylsilylethane [F3SiCH2CH2Si(CH3)3, FSMSE] condensed on a Au surface. The photoelectron spectrum of FSMSE has two peaks for 2p-electron emission: One for the Si atom bonded to three methyl groups (Si [Me]) and one for the Si atom bonded to three F atoms (Si [F]). H+ and F+ ions are predominantly desorbed coincidentally with the Si[Me]:2p and Si[F]:2p electrons. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0268-2605
    Keywords: Organoaluminum ; photoionization ; synchrotron radiation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dissociation processes of the organoaluminum compounds Al2(CH3)6 and Al2(CH3)3Cl3 have been studied in the range of valence and Al:2p core-level ionization by means of photoelectron-photoion and photoion-photoion coincidence techniques. The double-ionization threshold and the Al:2p core-ionization threshold of Al2(CH3)6 are estimated to be about 30 and 80 eV1 eV = 96.4853 kJ mol-1. respectively. The relative yields of the H+=Al+ and H+=CHm,+ (m′ = 0-3) ion pairs are enhanced around the Al:2p core-ionization threshold of Al2(CH3)6. The photoion-photoion coincidence intensities of Al2(CH3)3Cl3 are negligibly small throughout the energy range studied. The ratio of the relative yield of AlC2H6+ to that of Al+ increases smoothly through the Al:2p core-ionization and/or excitation region of Al2(CH3)3Cl3. The variation of the fragmentation pattern with photon energy is discussed in conjunction with the relevant electronic states.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Ionic fragmentation following 3d core photoexcitation of trimethylgallium has been studied in the vapor phase using synchrotron radiation. The threshold electron spectrum and photoionization efficiency curves are presented and discussed. The Ga+ and GaMe+ ions are predominantly produced following 3d photoexcitation. The fragmentation patterns following the 3d core excitation of trimethylgallium can be explained in terms of the hybrid orbitals constructed from the 3d, 4s, and 4p atomic orbitals.
    Type of Medium: Electronic Resource
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