Effects of Adsorption and Thermal Desorption of Atomic Hydrogen on Electronic and Atomic Structures of Si(111)($\sqrt{3}\times\sqrt{3}$)-Al Surface

1992 ◽  
Vol 31 (Part 2, No. 2A) ◽  
pp. L123-L126 ◽  
Author(s):  
Sung-Te Li ◽  
Shigehiko Hasegawa ◽  
Hisao Nakashima
Keyword(s):  
Thermal Desorption ◽  
Atomic Hydrogen ◽  
Atomic Structures

Absorption of gas-phase atomic hydrogen by Si(100): Effect of surface atomic structures

2001 ◽  
Vol 79 (1) ◽  
pp. 36-38 ◽  
Author(s):  
Jae Yeol Maeng ◽  
Sehun Kim ◽  
S. K. Jo ◽  
W. P. Fitts ◽  
J. M. White
Keyword(s):  
Gas Phase ◽  
Atomic Hydrogen ◽  
Atomic Structures ◽  
Effect Of Surface

Hydrogen--Halogen Exchange Reactions on Silicon (100)

1990 ◽  
Vol 204 ◽  
Author(s):  
R.E. Thomas ◽  
R.A. Rudder ◽  
R.J. Markunas
Keyword(s):  
Thermal Desorption ◽  
Atomic Hydrogen ◽  
Reverse Reaction ◽  
Thermal Mass ◽  
Exchange Reactions ◽  
Halogen Exchange ◽  
Reverse Sequence

ABSTRACTUsing thermal mass desorption and LEED we have studied interactions of H, C12, and F2 with a silicon (100) surface, and exchange reactions of the gases with adsorbates on the silicon (100) surface. Thermal desorption spectra were measured for surfaces dosed with H, C12, and F2 singly and then for surfaces dosed first with a halogen and then atomic hydrogen. Finally, the reverse sequence was studied, with atomic hydrogen dosing and then the halogen exposure. Results indicate that the molecular halogens C12 and F2 are not effective at removing H from a Si (100) surface. However, for the reverse reaction, atomic hydrogen appears quite effective at removing the halogens.

ADSORPTION DYNAMICS OFCO2ON HYDROGEN PRECOVEREDZn-ZnO(0001): A MOLECULAR BEAM STUDY

2004 ◽  
Vol 11 (06) ◽  
pp. 521-529 ◽  
Author(s):  
J. WANG ◽  
U. BURGHAUS
Keyword(s):  
Monte Carlo ◽  
Binding Energy ◽  
Thermal Desorption ◽  
Impact Energy ◽  
Atomic Hydrogen ◽  
Molecular Beam ◽  
Thermal Desorption Spectroscopy ◽  
Adsorption Dynamics ◽  
Site Blocking ◽  
The Impact

Presented are initial, S0, and coverage, Θ, dependent, S(Θ), adsorption probability measurements, respectively, of CO2adsorption on a hydrogen precovered, polar, Zn -terminated surface of ZnO , parametric in the impact energy, Ei, and atomic hydrogen precoverage, ΘH. Furthermore, CO2Thermal Desorption Spectroscopy has been used to estimate ΘHas well as the binding energy of CO2on H / Zn - ZnO . The S(Θ) curves are below Ei=0.56 eV , consistent with precursor-mediated adsorption (S~ const ), and above that impact energy with adsorbate-assisted adsorption (S increases with Θ). Although a decrease in the CO2binding energy from 32.5 to 28.8 kJ/mol with ΘHis present, S(Θ, ΘH) curves are consistent with a physical site blocking, as demonstrated by Monte Carlo Simulations.

scholarly journals Revealing Hydrogen States in Carbon Structures by Analyzing the Thermal Desorption Spectra

2022 ◽  
Vol 8 (1) ◽  
pp. 6
Author(s):  
Yury S. Nechaev ◽  
Evgeny A. Denisov ◽  
Nadezhda A. Shurygina ◽  
Alisa O. Cheretaeva ◽  
Ekaterina K. Kostikova ◽  
...  
Keyword(s):  
Thermal Desorption ◽  
Atomic Hydrogen ◽  
Hydrogen Desorption ◽  
High Energy ◽  
Second Order ◽  
Main Research ◽  
Carbon Structures ◽  
Exponential Factors ◽  
Relationship Of ◽  
Preliminary Description

An effective methodology for the detailed analysis of thermal desorption spectra (TDS) of hydrogen in carbon structures at micro- and nanoscale was further developed and applied for a number of TDS data of one heating rate, in particular, for graphite materials irradiated with atomic hydrogen. The technique is based on a preliminary description of hydrogen desorption spectra by symmetric Gaussians with their special processing in the approximation of the first- and the second-order reactions. As a result, the activation energies and the pre-exponential factors of the rate constants of the hydrogen desorption processes are determined, analyzed and interpreted. Some final verification of the results was completed using methods of numerical simulation of thermal desorption peaks (non-Gaussians) corresponding to the first- and the second-order reactions. The main research finding of this work is a further refinement and/or disclosure of poorly studied characteristics and physics of various states of hydrogen in microscale graphite structures after irradiation with atomic hydrogen, and comparison with the related results for nanoscale carbon structures. This is important for understanding the behavior and relationship of hydrogen in a number of cases of high energy carbon-based materials and nanomaterials.

Silicon Nanofabrication and Chemical Modification by UHV-STM

1995 ◽  
Vol 380 ◽  
Author(s):  
J. W. Lyding ◽  
T.-C. Shen ◽  
G. C. Abeln ◽  
C. Wang ◽  
E. T. Foley ◽  
...  
Keyword(s):  
Chemical Modification ◽  
Field Emission ◽  
Thermal Desorption ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Lower Energy ◽  
Vibrational Excitation ◽  
Hydrogen Desorption ◽  
Hydrogen Passivation ◽  
Electron Stimulated Desorption

ABSTRACTPatterning on the 10 Å size scale has been achieved with a UHV-STM for Si(100)-2×1:H surfaces. Hydrogen passivation serves as a monolayer resist which the STM locally desorbs, exposing clean Si(100)-2×1 for selective chemistry. Two mechanisms have been identified for hydrogen removal by STM electrons: in the field emission regime direct electron stimulated desorption of hydrogen occurs whereas, in the lower energy tunneling regime, hydrogen desorption results from vibrational excitation of the Si-H bond at high tunneling currents. Furthermore, we find that atomic hydrogen is liberated in contrast to molecular hydrogen evolved during thermal desorption. Selective oxidation and nitridation of the STM-patterned areas has been achieved.

Finding the Right Problems: Some HREM Applications to Interfaces

1984 ◽  
Vol 42 ◽  
pp. 376-379
Author(s):  
D. Cherns
Keyword(s):  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Resolution Electron ◽  
Point To Point ◽  
The Right ◽  
New Generation ◽  
Better Than

The use of high resolution electron microscopy (HREM) to determine the atomic structure of grain boundaries and interfaces is a topic of great current interest. Grain boundary structure has been considered for many years as central to an understanding of the mechanical and transport properties of materials. Some more recent attention has focussed on the atomic structures of metalsemiconductor interfaces which are believed to control electrical properties of contacts. The atomic structures of interfaces in semiconductor or metal multilayers is an area of growing interest for understanding the unusual electrical or mechanical properties which these new materials possess. However, although the point-to-point resolutions of currently available HREMs, ∼2-3Å, appear sufficient to solve many of these problems, few atomic models of grain boundaries and interfaces have been derived. Moreover, with a new generation of 300-400kV instruments promising resolutions in the 1.6-2.0 Å range, and resolutions better than 1.5Å expected from specialist instruments, it is an appropriate time to consider the usefulness of HREM for interface studies.

Quasiperiodic interfaces: HREM observations of grain and phase boundaries

1990 ◽  
Vol 48 (4) ◽  
pp. 332-333
Author(s):  
K. L. Merkle
Keyword(s):  
Atomic Structure ◽  
Direct Determination ◽  
Lattice Parameter ◽  
Atomic Scale ◽  
Misfit Dislocations ◽  
Oxide Systems ◽  
Atomic Structures ◽  
Periodic Arrays ◽  
Parameter Ratio ◽  
Metal Metal

The atomic structures of internal interfaces have recently received considerable attention, not only because of their importance in determining many materials properties, but also because the atomic structure of many interfaces has become accessible to direct atomic-scale observation by modem HREM instruments. In this communication, several interface structures are examined by HREM in terms of their structural periodicities along the interface.It is well known that heterophase boundaries are generally formed by two low-index planes. Often, as is the case in many fcc metal/metal and metal/metal-oxide systems, low energy boundaries form in the cube-on-cube orientation on (111). Since the lattice parameter ratio between the two materials generally is not a rational number, such boundaries are incommensurate. Therefore, even though periodic arrays of misfit dislocations have been observed by TEM techniques for numerous heterophase systems, such interfaces are quasiperiodic on an atomic scale. Interfaces with misfit dislocations are semicoherent, where atomically well-matched regions alternate with regions of misfit. When the misfit is large, misfit localization is often difficult to detect, and direct determination of the atomic structure of the interface from HREM alone, may not be possible.

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