Laser Induced Decomposition of Triethylgallium and Trimethylgallium Adsorbed on GaAs(100)

1988 ◽  
Vol 129 ◽  
Author(s):  
J. A. Mccaulley ◽  
V. R. Mccrary ◽  
V. M. Donnelly
Keyword(s):  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Electronic Excitation ◽  
Removal Rate ◽  
Laser Wavelength ◽  
High Fluence ◽  
X Ray ◽  
Two Photon ◽  
Induced Decomposition

ABSTRACTWe report X-ray photoelectron spectroscopy (XPS) studies of excimer laser stimulated decomposition of triethylgallium (TEGa) and trimethylgallium (TMGa) adsorbed on Gastabilized GaAs(100) surfaces in ultrahigh vacuum. TEGa and TMGa dissociatively chemisorb on GaAs at room temperature, whereupon irradiation by an excimer laser (at 193 or 351 nm) leads to further dissociation and desorption of carbon-containing species. The carbon removal rate (per laser pulse) decreases as carbon is removed suggesting multiple reaction sites, coverage dependent Arrhenius parameters, or second-order reactions. Based on the dependence of the rate on laser wavelength and fluence, we conclude that at low fluence, a two-photon electronic excitation of the adsorbate occurs, while at high fluence, laser induced pyrolysis dominates.

Studies of Carbon Nitride Thin Films Synthesized by KrF Excimer Ablation of Graphite in Nitrogen Atmosphere

1998 ◽  
Vol 526 ◽  
Author(s):  
Z.M. Ren ◽  
Y.F. Lu ◽  
W.D. Song ◽  
D.S.H. Chan ◽  
T.S. Low ◽  
...  
Keyword(s):  
Thin Films ◽  
Excimer Laser ◽  
Photoelectron Spectroscopy ◽  
Carbon Nitride ◽  
Nitrogen Pressure ◽  
Laser Wavelength ◽  
Nitrogen Atmosphere ◽  
Amorphous Semiconductor ◽  
X Ray ◽  
Krf Excimer Laser

AbstractCarbon nitride thin films were deposited on silicon wafers by pulsed KrF excimer laser (wavelength 248 nm, duration 23 ns) ablation of graphite in nitrogen atmosphere. Different fluences of the excimer laser and pressures of the nitrogen atmosphere were used in order to achieve a high nitrogen content in the deposited thin films. Fourier Transform Infra-red (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to identify the binding structure and the content of the nitrogen species in the deposited thin films. The highest N/C ratio 0.42 was achieved at an excimer laser fluence of 0.8 Jcm -2with a repetition rate of 10 Hz under the nitrogen pressure of PN=100 mTorr. A high content of C=N double bond instead of C-N triple bond was indicated in the deposited thin films. Ellipsometry was used to analyze the optical properties of the deposited thin films. The carbon nitride thin films have amorphous-semiconductor-like characteristics with the optical band gap Eop, as high as 0.42 eV.

PREPARATION OF Au-LOADED TiO2 BY PHOTOCHEMICAL DEPOSITION AND OZONE PHOTOCATALYTIC DECOMPOSITION

2006 ◽  
Vol 13 (01) ◽  
pp. 51-55 ◽  
Author(s):  
PANKE HE ◽  
MIN ZHANG ◽  
DONGMEI YANG ◽  
JIANJUN YANG
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Au Nanoparticles ◽  
Diffuse Reflectance Spectroscopy ◽  
Removal Rate ◽  
Photocatalytic Decomposition ◽  
X Ray ◽  
Transmission Electron ◽  
Photocatalytic Removal ◽  
Photochemical Deposition

In this paper, Au -loaded TiO 2( Au/TiO 2) photocatalysts were prepared by photochemical deposition method and characterized by transmission electron microscopy, diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The results indicated the metallic Au nanoparticles were deposited on the surface of TiO 2 after the high-pressure mercury irradiation and regarded as an electronegative center. The photocatalytic decomposition of gaseous ozone was investigated on TiO 2 and Au -loaded TiO 2 at room temperature. Results indicated that the photocatalytic conversion of ozone can be improved by Au/TiO 2 and photocatalytic activity increased with the increase of the photodeposition time. The photocatalytic removal rate of ozone remained above 96% on the surface of 1% Au/TiO 2 with photodeposition for 120 min under black lamp irradiation for 20 h. Au cluster deposited on the surface of TiO 2 functioned not only as the electron trap center but also as the adsorption site of O 3 in photocatalytic reaction.

scholarly journals Synthesis of Magnetic Ferrocene-Containing Polymer with Photothermal Effects for Rapid Degradation of Methylene Blue

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 558
Author(s):  
Wenhui Zhu ◽  
Caiyun Zhang ◽  
Yali Chen ◽  
Qiliang Deng
Keyword(s):  
Methylene Blue ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Degradation Rate ◽  
Model Compound ◽  
Vibrating Sample Magnetometer ◽  
Simulated Sunlight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir

Photothermal materials are attracting more and more attention. In this research, we synthesized a ferrocene-containing polymer with magnetism and photothermal properties. The resulting polymer was characterized by Fourier-transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Its photo-thermocatalytic activity was investigated by choosing methylene blue (MB) as a model compound. The degradation percent of MB under an irradiated 808 nm laser reaches 99.5% within 15 min, and the degradation rate is 0.5517 min−1, which is 145 times more than that of room temperature degradation. Under irradiation with simulated sunlight, the degradation rate is 0.0092 min−1, which is approximately 2.5 times more than that of room temperature degradation. The present study may open up a feasible route to degrade organic pollutants.

scholarly journals A Highly Sensitive Room Temperature CO2 Gas Sensor Based on SnO2-rGO Hybrid Composite

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 522
Author(s):  
Zhi Yan Lee ◽  
Huzein Fahmi bin Hawari ◽  
Gunawan Witjaksono bin Djaswadi ◽  
Kamarulzaman Kamarudin
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Gas Sensor ◽  
Photoelectron Spectroscopy ◽  
Hybrid Composite ◽  
Room Temperature ◽  
Co2 Gas ◽  
X Ray ◽  
Wide Range ◽  
Co2 Gas Sensor

A tin oxide (SnO2) and reduced graphene oxide (rGO) hybrid composite gas sensor for high-performance carbon dioxide (CO2) gas detection at room temperature was studied. Since it can be used independently from a heater, it emerges as a promising candidate for reducing the complexity of device circuitry, packaging size, and fabrication cost; furthermore, it favors integration into portable devices with a low energy density battery. In this study, SnO2-rGO was prepared via an in-situ chemical reduction route. Dedicated material characterization techniques including field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) were conducted. The gas sensor based on the synthesized hybrid composite was successfully tested over a wide range of carbon dioxide concentrations where it exhibited excellent response magnitudes, good linearity, and low detection limit. The synergistic effect can explain the obtained hybrid gas sensor’s prominent sensing properties between SnO2 and rGO that provide excellent charge transport capability and an abundance of sensing sites.

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

Preparation of Novel Ag–Si–TiO2 Composite and Research on Its Photocatalytic Degradation of Formaldehyde

2021 ◽  
Vol 13 (3) ◽  
pp. 371-380
Author(s):  
Yongjun Wu ◽  
Nina Xie ◽  
Lu Yu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Removal Rate ◽  
Sol Gel ◽  
Catalytic Performance ◽  
Formaldehyde Concentration ◽  
Order Kinetic ◽  
Solution Ph ◽  
Visible Absorption ◽  
X Ray ◽  
Co Doped

A novel Ag–Si–TiO2 composite was prepared via sol–gel method for removing residual formaldehyde in shiitake mushroom. The structure of Ag–Si–TiO2 composite was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. Ultraviolet-visible absorption spectroscopy (UV-Vis) and N2 adsorption-desorption tests showed that Ag and Si co-doped decreased the band gap, the Brunauer-Emmett-Teller (BET) specific surface area of the samples increased and the recombination probability of electron-hole pairs (e--h+) reduced. Effect on removal rate of formaldehyde with different Ag-Si co-doped content, formaldehyde concentration and solution pH were investigated, and the results showed that 6.0 wt%Ag-3.0 wt%Si-TiO2 samples had an optimum catalytic performance, and the degradation efficiency reached 96.6% after 40 W 365 nm UV lamp irradiation for 360 min. The kinetics of formaldehyde degradation by Ag–Si–TiO2 composite photocatalyst could be described by Langmuir-Hinshelwood first-order kinetic model.

scholarly journals Characterization of Ti/SnO2 Interface by X-ray Photoelectron Spectroscopy

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 202
Author(s):  
Miranda Martinez ◽  
Anil R. Chourasia
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Chemical Interaction ◽  
Photoelectron Spectra ◽  
X Ray ◽  
Increasing Trend ◽  
Substrate Temperatures ◽  
Beam Technique

The Ti/SnO2 interface has been investigated in situ via the technique of x-ray photoelectron spectroscopy. Thin films (in the range from 0.3 to 1.1 nm) of titanium were deposited on SnO2 substrates via the e-beam technique. The deposition was carried out at two different substrate temperatures, namely room temperature and 200 °C. The photoelectron spectra of tin and titanium in the samples were found to exhibit significant differences upon comparison with the corresponding elemental and the oxide spectra. These changes result from chemical interaction between SnO2 and the titanium overlayer at the interface. The SnO2 was observed to be reduced to elemental tin while the titanium overlayer was observed to become oxidized. Complete reduction of SnO2 to elemental tin did not occur even for the lowest thickness of the titanium overlayer. The interfaces in both the types of the samples were observed to consist of elemental Sn, SnO2, elemental titanium, TiO2, and Ti-suboxide. The relative percentages of the constituents at the interface have been estimated by curve fitting the spectral data with the corresponding elemental and the oxide spectra. In the 200 °C samples, thermal diffusion of the titanium overlayer was observed. This resulted in the complete oxidation of the titanium overlayer to TiO2 upto a thickness of 0.9 nm of the overlayer. Elemental titanium resulting from the unreacted overlayer was observed to be more in the room temperature samples. The room temperature samples showed variation around 20% for the Ti-suboxide while an increasing trend was observed in the 200 °C samples.

scholarly journals Synthesis and characterization of nanoscale composite particles formed by 2D layers of Cu-Fe sulfide and Mg-based hydroxide

2021 ◽  
Author(s):  
Yuri Mikhlin ◽  
Roman Borisov ◽  
Sergey Vorobyev ◽  
Yevgeny Tomashevich ◽  
Alexander Romanchenko ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Localized Surface Plasmon ◽  
X Ray ◽  
Zeta Potentials ◽  
Dielectric Resonance ◽  
Magnetic Dynamic ◽  
20 Nm ◽  
Electron Energy Loss

Two-dimensional phenomena are attracting enormous interest at present and the search for novel 2D materials is very challenging. We propose here the layered material valleriite composed of altering atomic sheets of Cu-Fe sulfide and Mg-based hydroxide synthesized via a simple hydrothermal pathway as particles of 50-200 nm in the lateral size and 10-20 nm thick. The solid products and aqueous colloids prepared with various precursor ratios were examined using XRD, TEM, EDS, X-ray photoelectron spectroscopy (XPS), reflection electron energy loss spectroscopy (REELS), Raman, Mössbauer, UV-vis-NIR spectroscopies, magnetic, dynamic light scattering, zeta potential measurements. The material properties are largely determined by the narrow-gap (less than 0.5 eV) sulfide layers containing Cu+ and Fe3+ cations, monosulfide and minor polysulfide anions but are strongly affected by the hydroxide counterparts. Particularly, Fe distribution between sulfide (55-90%) and magnesium hydroxide layers is controlled through insertion of Al into the hydroxide part and by Cr and Co dopants entering both layers. Room-temperature Mössbauer signals of paramagnetic Fe3+ transformed to several Zeeman sextets with hyperfine magnetic fields up to 500 kOe in the sulfide layers at 4 K. Paramagnetic or more complicated characters were observed for valleriites with higher and lower Fe concentrations in hydroxide sheets, respectively. Valleriite colloids showed negative zeta potentials, suggesting negative electric charging of the hydroxide sheets, and optical absorption maxima between 500 nm and 700 nm, also depended on the Fe distribution. The last features observed also in the REELS spectra may be due to localized surface plasmon or, more likely, quasi-static dielectric resonance. The tunable composition, electronic, magnetic, optic and surface properties highlight valleriites as a rich platform for novel 2D composites promising for numerous applications.

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