• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.728-734
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• 1996

To obtain the relation in the electrochemical reduction of $CO_2$ in aqueous $KHCO_3$ colution between an activity for the product and the nature of Cu electrode, the electrode surface was characterized by using two methods: X-ray photoelectron spectroscopy (XPS) and photoelectron emission (PE) measurement. Electrolyses were performed with Cu electrodes pretreated in several ways. The distribution of the products changed drastically with electrolysis time and the pretreatment method. The features in XPS spectra were closely connected with the product distribution. The oxide film at the electrode surface was gradually reduced to bare Cu metal with electrolysis time, resulting in a variation of the product distribution. PE was measured by verying the wavelength of incident light at several temperatures. The dependence of PE on the measurement temperature changed greatly before and after electrolysis.

• Journal of Information Display
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• v.6 no.1
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• pp.28-32
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• 2005

The electronic structures of Al/RbF/tris-(8-hydroxyquinoline)aluminium ($Alq_3$) and $Al/CaF_2/Alq_3$interfaces were investigated using x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). For both systems, the UPS showed a significant valence band shift following the deposition of the thin fluoride layers on $Alq_3$. However, the formation of gap state in valence region and the extra peak N 1s core level spectra showed different trends, suggesting that the alkali fluoride and alkali-earth fluoride interlayer have different reaction mechanisms at the interface between Al cathode and $Alq_3$. In addition, the deposition of Al has considerably less effect on the valence band shift compared to the deposition of both RbF and $CaF_2$. These results suggest that the charge transfer across the interface and the resulting gap state formation may have lesser effect on the enhancement of organic light-emitting device performance than the observed valence band shift, which is thought to lower the electron injection barrier.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.31-36
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• 2006

By analyzing the Ge 34 core-level photoelectron spectrum, we studied the structure of the $Li/Ge(111)-3\times1$ surface. Two surface related components tying on either side of the main bulk peak were identified in the Ge 3d spectrum. The existence and the position of the two surface components in the core-level spectrum from $Li/Ge(111)-3\times1$ is similar to those of the $Li/Ge(111)-3\times1$, suggesting the similarities in structure of the two surfaces. The core-level photoelectron spectra of the Li-induced $Li/Ge(111)-3\times1$ surface are well consistent with the honeycomb-chain-channel model, which was proposed as the structure of the $Si/Ge(111)-3\times1$ induced by alkali metals.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.149.1-149.1
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• 2013

Noble metal silicides are widely used in silicon based microelectronic and optoelectronic devices. Among them, as compared to other silicides, structural and electronic properties of platinum silicide (PtSi) are found to be less sensitive to change in its dimensions. PtSi is known to overcome the junction spiking problems of Al-Si contacts. Present study is regarding the spatial evolution of platinum silicide in Pt/SiOx/Si. Scanning photoelectron emission microscopy (SPEM) was used for this purpose. SPEM images were obtained for pristine samples and after an annealing at $500^{\circ}C$ for 1 hr. Core-level spectra were recorded at different points in SPEM images contrasted by the intensity of Pt 4f7/2. Both Pt 4f and Si 2p spectra reveal the formation of PtSi after annealing. However, in contrast to earlier reports, PtSi formation is found to be non-uniform confirmed by the SPEM images and from the core level spectra taken at different intensity points.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3217-3220
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• 2010

The electronic structures and bonding configuration of histidine on Ge(100) have been investigated with various sample treatments using core-level photoemission spectroscopy (CLPES). Interpretation of the Ge 3d, C 1s, N 1s, and O 1s core level spectra being included in these systems revealed that both the imino nitrogen in the imidazole ring and the carboxyl group in the glycine moiety concurrently participate in the adsorption of histidine on a Ge(100) surface at 380 K. Moreover, we could clearly confirm that the imino nitrogen with a free lone pair in the imidazole group adsorbs on Ge(100) more strongly than the carboxyl group in the glycine moiety by examining systems annealed at various temperatures.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.215-215
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• 2011

The bonding configuration and adsorption stability of alanine and leucine adsorbed on Ge(100)-2${\times}$1 surface were investigated and compared using core-level photoemission spectroscopy (CLPES) and density functional theory (DFT) calculations. The bonding configuration, stability, and adsorption energies were evaluated for two different coverage levels. In both cases, the C 1s, N 1s, and O 1s core-level spectra at a low coverage (0.30 ML) indicated that the carboxyl and amine groups participated in bonding with the Ge(100) surface in an "O-H dissociated-N dative bonded structure". At high coverage levels (0.60 ML), both this structure and an "O-H dissociation bonded structure" were present. As a result, we found that alanine adsorbs more easily (lower adsorption energy) than leucine on Ge(100) surfaces due to less steric hindrance of side chain.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.189-194
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• 2002

Two-photon resonant third photon ionization of atomic bromine $(4p^5\;^2P_{3/2}\;and\;^2P_{1/2})$ has been studied using a photoelectron imaging spectroscopy in the wavelength region 250 - 278 nm. The technique has yielded simultaneously both relative branching ratios to the three levels of $Br^+(^3P_2,\;^3P_{0.1}\;and^1D_2)$ with $4p^4$ configuration and the angular distributions of outgoing photoelectrons. The product branching ratios reveal a strong propensity to populate particular levels in many cases. Several pathways have been documented for selective formation of $Br^+(^3P_2)$ and $Br^+(^3P_{0.1})$ ions. In general, the final ion level distributions are dominated by the preservation of the ion core configuration of a resonant excited state. Some deviations from this simple picture are discussed in terms of the configuration interaction of resonant states and the autoionization in the continuum. The photoelectron angular distributions are qualitatively similar for all transitions, with a positive $A_2$ anisotropy coefficient of 1.0-2.0 and negligible $A_4$ in most cases, which suggests that the angular distribution is mainly determined by the single-photon ionization process of a resonant excited state induced from the third photon absorption.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.51-56
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• 1996

Structural properties of rf sputtered boron nitride films were studied as a function of deposition parameters such as nitrogen pressure, substrate temperature and substrate bias using X-ray photoelectron spectroscopy and Auger electron spectroscopy. Composition and information on chemical bonding of resultant films was determined by XPS. XPS core level spectra showed that ratio of boron to nitrogen varied from 3.11 to 1.45 with respect to partial nitrogen pressure. Curve fitting of XPS spectra revealed three kinds of bonding mechanism of boron in the films. XPS peak positions of both B 1s and N 1s shifted to higher energy with higher nitrogen pressure as well as increase in substrate bias voltage. AES was used to see possible contamination of films by carbon or oxygen as well.

• Bulletin of the Korean Chemical Society
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• v.17 no.12
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• pp.1154-1157
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• 1996

The growth and electronic properties of ultrathin silver films deposited onto Pt(211) surface were studied using Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and x-ray photoelectron spectroscopy. The AES and LEED results indicate that the silver grows by a layer by layer growth followed by three dimensional islands growth. The XPS results show that the Ag 3d core-level binding energy of Ag overlayers on Pt(211) shifts toward lower binding energy relative to the bulk value at lower Ag coverage. This negative binding energy shift of the Ag 3d core level is explained by the reduced coordination number of the overlayer atoms and the resulting initial state band narrowing effect suggested by Wertheim and Citrin [Phys. Rev. Lett. 1978, 41, 1425].

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.17-20
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• 2003

We have studied magnetic and structural properties of ultrathin Ni films grown on PI(lII) surface using in situ surface magneto-optic Kerr effect and X-ray photoelectron spectroscopy. Perpendicular magnetic anisotropy was absent, and longitudinal Kerr signal was only detectable for Ni films thicker than 6 monolayers. Enhancement in longitudinal Kerr signal by 30% was achieved by post-annealing at temperatures below 800K, but upon annealing at 820K, surface alloy was formed. By using core-level binding-energy shifts, the composition was determined to be Ni 70 at. %.