کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5423155 | 1507952 | 2010 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Relative reactivities of amino and ethenyl groups in allylamine on Si(100)2Â ÃÂ 1: Temperature-dependent X-ray photoemission and thermal desorption studies of a common linker molecule
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
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چکیده انگلیسی
The room-temperature adsorption and thermal evolution of allylamine on Si(100)2Â ÃÂ 1 have been investigated by using temperature-dependent X-ray photoelectron spectroscopy (XPS) and thermal desorption spectrometry (TDS). The presence of a broad N 1Â s feature at 398.9Â eV, attributed to a NâSi bond, indicates NâH dissociative adsorption. On the other hand, the presence of C 1Â s features at 284.6Â eV and 286.2Â eV, corresponding to CâC and CâN, respectively, and the absence of the SiâC feature expected at 283.2Â eV shows that [2Â +Â 2] CâC cycloaddition does not occur at room temperature. These XPS data are consistent with the unidentate staggered and eclipsed allylamine conformer adstructures arising from NâH dissociation and not [2Â +Â 2] CâC cycloaddition. The apparent conversion of the N 1Â s feature for SiâN(H)âC at 398.9Â eV to that for SiâN(H) at 397.7Â eV and the total depletion of C 1Â s feature for CâN at 286.2Â eV near 740Â K indicates cleavage of the CâN bond, leaving behind a SiâN(H) radical. Furthermore, the CâC C 1Â s feature at 284.6Â eV undergoes steep intensity reduction between 740Â K and 825Â K, above which a new C 1Â s feature at 283.2Â eV corresponding to SiC is found to emerge. These spectral changes suggest total dissociation of the ethenyl fragment and the formation of SiC. Moreover, while the total N 1Â s intensity undergoes a minor reduction (24%) upon annealing up to 1090Â K, a considerable reduction (43%) is found in the overall C 1Â s intensity. This observation is consistent with our TDS data, which shows the desorption of C-containing molecules including propene and ethylene at 580Â K and of acetylene at 700Â K. The lack of N-containing desorbates suggests that the dissociated N species are likely bonded to multiple surface Si atoms or diffused into the bulk. Interestingly, both the staggered and eclipsed NâH dissociative adstructures are found to have a less negative adsorption energy than the [N, C, C] tridentate or the [2Â +Â 2] CâC cycloaddition adstructures by our DFT calculations, which suggests that the observed formation of NâH dissociative adstructures is kinetically favored on the Si(100)2Â ÃÂ 1 surface.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface Science - Volume 604, Issues 13â14, 15 July 2010, Pages 1073-1081
Journal: Surface Science - Volume 604, Issues 13â14, 15 July 2010, Pages 1073-1081
نویسندگان
A. Radi, M. Ebrahimi, K.T. Leung,