Browsing by Author "Süzer, Şefik"
Now showing items 1-20 of 116
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AC electrowetting modulation of low-volatile liquids probed by XPS: dipolar vs ionic screening
Aydoğan-Göktürk, Pınar; Ülgüt, Burak; Süzer, Şefik (American Chemical Society, 2019)X-ray photoelectron spectroscopic (XPS) data have been recorded for a low-molecular-weight poly(ethylene glycol) microliter-sized sessile liquid drops sitting on a dielectric covered planar electrode while imposing a ±6 V ... -
Analysis of Fe nanoparticles using XPS measurements under d.c. or pulsed-voltage bias
Süzer, Şefik; Baer, D. R.; Engelhard, M. H. (2010)The impact of solution exposure on the charging properties of oxide coatings on Fe metal-core oxide-shell nanoparticles has been examined by sample biasing during XPS measurements. The Fe nanoparticles were suspended in ... -
Analysis of polymers using evolved-gas and direct-pyrolysis techniques
Fares, M. M.; Yalcin, T.; Hacaloglu, J.; Gungor, A.; Süzer, Şefik (Royal Society of Chemistry, 1994)Thermal analysis of polystyrene, poly(p-methylstyrene) and poly(α-methylstyrene) has been carried out using evolved-gas analysis by infrared and mass spectrometry, and direct-pyrolysis analysis by mass spectrometric ... -
Analysis of surface structures using XPS with external stimuli
Ertaş, Gülay; Süzer, Şefik (Springer, Dordrecht, 2006)X-ray Photoelectron Spectroscopy, XPS, due to the perfect match of its probe length (1-10 nm) to nanoparticle size, chemical specificity, and susceptibility to electrical charges, is ideally suited for harvesting chemical, ... -
Au nanoparticles in PMMA matrix: In situ synthesis and the effect of Au nanoparticles on PMMA conductivity
Yilmaz, E.; Süzer, Şefik (Elsevier, 2010-09-01)Thin PMMA films with and without gold nanoparticles were subjected to +/-10V d.c. and a.c. (square wave) excitations in various frequencies while recording their XPS spectra, and the resulting differences due to charging ... -
Band alignment issues in metal/dielectric stacks: a combined photoemission and inverse photoemission study of the HfO 2/Pt and HfO 2/Hf systems
Sayan, S.; Bartynski, R.A.; Robertson J.; Suehle, J. S.; Vogel, E.; Nguyen, N. V.; Ehrstein, J.; Kopanski, J. J.; Süzer, Şefik; Holl, M. B.; Garfunkel, E. (Electrochemical Society, 2004)We have studied the HfO 2/Hf and HfO 2/Pt systems by photoemission and inverse photoemission spectroscopies. It is found that the "effective workfunction" of metals in multilayer structures are different than their vacuum ... -
Band alignment issues related to HfO2/SiO2/p-Si gate stacks
Sayan, S.; Emge, T.; Garfunkel, E.; Zhao, X.; Wielunski, L.; Bartynski, R. A.; Vanderbilt, D.; Suehle, J. S.; Süzer, Şefik; Banaszak Holl, M. (American Institute of Physics, 2004-12-15)The valence and conduction band densities of states for the HfO2/SiO2/Si structure are determined by soft x-ray photoemission and inverse photoemission. First principles calculations are used to help in assigning valence ... -
Band-Bending at buried SiO2/Si interface as probed by XPS
Çopuroğlu, M.; Sezen, H.; Opila, R. L.; Süzer, Şefik (American Chemical Society, 2013)X-ray photoelectron spectroscopy is used to probe the photoinduced shifts in the binding energies of Si2p, O1s, and C1s of the SiO2/Si interfaces of a number of samples having oxide and/or thin organic layers on top of p- ... -
Carbon supported nano-sized Pt-Pd and Pt-Co electrocatalysts for proton exchange membrane fuel cells
Kadirgan, F.; Kannan, A. M.; Atilan, T.; Beyhan, S.; Ozenler, S. S.; Süzer, Şefik; Yörür, A. (2009)Nano-sized Pt-Pd/C and Pt-Co/C electrocatalysts have been synthesized and characterized by an alcohol-reduction process using ethylene glycol as the solvent and Vulcan XC-72R as the supporting material. While the Pt-Pd/C ... -
CeOx/Al2O3 thin films on stainless steel substrate-dynamical X-ray photoelectron spectroscopy investigations
Avramova, I.; Süzer, Şefik; Guergova, D.; Stoychev, D.; Stefanov, P. (Elsevier, 2013)The CeOx/Al2O3 thin films on stainless steel with different ceria loading were subjected to a.c. (square wave) pulses at various frequencies in the range 10- 3 to 100 kHz while recording X-ray photoelectron spectra. The ... -
Characterization of degradation products of polyethylene oxide by pyrolysis mass spectrometry
Fares, M. M.; Hacaloglu, J.; Süzer, Şefik (Pergamon Press, 1994)The techniques of direct and indirect (evolved gas analysis) pyrolysis MS are used to characterize the thermal degradation products of polyethylene oxide. Using direct pyrolysis MS technique the main degradation process ... -
Charge storage and release onto Au and Ag nanoparticles in aqueous medium as probed by optical spectroscopy
Tunc, I.; Sezen, H.; Guvenc, H. O.; Süzer, Şefik (Cognizure, 2014)Gold and silver nanoparticles in aqueous solutions can store negative or positive charges when, respectively, NaBH4, KI are introduced into the same media. The charge storage can be followed by the spectral shifts in the ... -
Charging / discharging of thin PS / PMMA films as probed by dynamic x-ray photoelectron spectroscopy
Sezen, H.; Ertas, G.; Dâna, A.; Süzer, Şefik (2007)Polystyrene / polymethyl methacrylate (PS-PMMA) thin films were analyzed for detecting phase separation as well as probing their electrical responses by XPS. It was also shown that electrical parameters like resistance or ... -
Charging/discharging dynamics of CdS and CdSe films under photoillumination using dynamic x-ray photoelectron spectroscopy
Sezen, H.; Süzer, Şefik (A I P Publishing LLC, 2010)Thin films of CdS and CdSe are deposited on HF-cleaned Si O2 /Si substrates containing ∼5 nm thermally grown silicon oxide. x-ray photoelectron spectroscopy (XPS) data of these films are collected in a dynamic mode, which ... -
Charging/discharging of Au (core)/silica (shell) nanoparticles as revealed by XPS
Tunc, I.; Demirok, U. K.; Süzer, Şefik; Correa-Duatre, M. A.; Liz-Marzan, L. M. (American Chemical Society, 2005)By recording XPS spectra while applying external voltage stress to the sample rod, we can control the extent of charging developed on core-shell-type gold nanoparticles deposited on a copper substrate, in both steady-state ... -
Chemical Visualization of a GaN p-n junction by XPS
Caliskan, D.; Sezen H.; Özbay, Ekmel; Süzer, Şefik (Nature Publishing Group, 2015)We report on an operando XPS investigation of a GaN diode, by recording the Ga2p 3/2 peak position under both forward and reverse bias. Areal maps of the peak positions under reverse bias are completely decoupled with ... -
Chemically addressed switching measurements in graphene electrode memristive devices using in situ XPS
Kocabaş, Coşkun; Köymen, Itır; Aydoğan Göktürk, Pınar; Süzer, Şefik (Royal Society of Chemistry, 2019-08)The memristor has been the topic of heated research activity since the Pt/TiO2/TiOx/Pt structure was reported by Hewlett-Packard Labs. The characteristics of memristors such as the pinched hysteresis loops and time and ... -
Coarse-grained electrostatic model including ion-pairing equilibrium that explains DC and AC X-ray photoelectron spectroscopy measurements on ionic liquids
Uzundal, Can Berk; Aydoğan-Göktürk, Pınar; Süzer, Şefik; Ülgüt, Burak (American Chemical Society, 2019)The dynamics of the electrochemical double layer in ionic liquids can be experimentally probed by a number of experimental techniques. Earlier, we reported on the results of an X-ray photoelectron spectroscopic investigation ... -
Collagen-chitosan scaffold modified with Au and Ag nanoparticles: synthesis and structure
Rubina, M. S.; Kamitov, E. E.; Zubavichus, Y. V.; Peters, G. S.; Naumkin, A. V.; Süzer, Şefik; Vasil'kov, A. Y. (Elsevier B.V., 2016)Nowadays, the dermal biomimetic scaffolds are widely used in regenerative medicine. Collagen-chitosan scaffold one of these materials possesses antibacterial activity, good compatibility with living tissues and has been ... -
Combined XPS and contact angle studies of ethylene vinyl acetate and polyvinyl acetate blends
Ucar, I. O.; Doganci, M. D.; Cansoy, C. E.; Erbil, H. Y.; Avramova, I.; Süzer, Şefik (Elsevier, 2011-09-01)In this study, we prepared thin films by blending ethylene vinyl acetate copolymers (EVA) containing 12-33 (wt.%) vinyl acetate (VA) with polyvinyl acetate (PVAc) and high density polyethylene homopolymers. Large area ...