Importance of Hydrocarbon Fragment Diffusion in the Formation of Adsorbed Alkyls via EID of Multilayers on Pt(111)

1997 ◽  
Vol 101 (24) ◽  
pp. 4781-4786 ◽  
Author(s):  
Yi-Li Tsai ◽  
Bruce E. Koel
Keyword(s):  
Hydrocarbon Fragment

INITIAL ENERGY OF HYDROCARBON FRAGMENT IONS

1963 ◽  
pp. 285-295 ◽  
Author(s):  
J. BRACHER ◽  
H. EHRHARDT ◽  
R. FUCHS ◽  
O. OSBERGHAUS ◽  
R. TAUBERT
Keyword(s):  
Initial Energy ◽  
Fragment Ions ◽  
Hydrocarbon Fragment

Adsorption and bonding of C1Hx and C2Hy on unreconstructed diamond(111). Dependence on coverage and coadsorbed hydrogen

1990 ◽  
Vol 5 (11) ◽  
pp. 2286-2295 ◽  
Author(s):  
S. P. Mehandru ◽  
Alfred B. Anderson
Keyword(s):  
Surface Coverage ◽  
Electron Delocalization ◽  
Orbital Method ◽  
Surface Carbon ◽  
Predominant Component ◽  
Full Structure ◽  
Adsorption Energies ◽  
Isomerization Energy ◽  
Low Coverage ◽  
Hydrocarbon Fragment

The adsorption and bonding of CH3, CH2, CH, C2H, and C2H2 fragments to clean and hydrogenated diamond(111) surfaces are investigated in the framework of the atom superposition and electron delocalization molecular orbital method. Low coverage calculations are performed using large cluster models for the surfaces, and high coverages are examined with band calculations on thick two-dimensional slabs with every surface carbon covered by a hydrocarbon fragment (i.e., 1:1 surface coverage). For low coverage adsorption on clean and H-covered surfaces the adsorption energies are in the order C2H>CH ≃ CH2>CH3. In each case, the predominant component of bonding is covalent in character and is a result of overlaps between the sp-hybridized singly occupied dangling surface state orbital on the surface carbon and the sp-hybridized orbital on the fragment carbon atom. While the charge transfer contribution to bonding is nearly the same for CH3, CH2, and CH fragments, it is significantly larger for C2H due to a comparatively stable radical orbital on C2H. C2H2 binds to the surface on the di-σ site where both its ends form bonds to the surface atoms. Onefold adsorption to a H-covered surface is predicted to be unstable. The 1:1 CH3 coverage on diamond(111) is highly unstable because of steric repulsions between adsorbate fragments due to their spacial proximity. This finding is supported by a calculation of the cis-trans isomerization energy of di-t-butyl ethylene, including full structure relaxations. At low coverage CH3 can bind on adjacent surface sites by tilting away from one another. The 1:1 coverage for CH2, CH, and C2H fragments is predicted to be stable on this surface.

Charge localization and the electron-impact fragmentation of carbonyl compounds

1967 ◽  
Vol 20 (11) ◽  
pp. 2387 ◽  
Author(s):  
JL Occolowitz
Keyword(s):  
Electron Impact ◽  
Carbonyl Group ◽  
Carbonyl Compounds ◽  
Charge Retention ◽  
Charge Localization ◽  
Appearance Potential ◽  
Impact Fragmentation ◽  
Group Structures ◽  
Hydrocarbon Fragment

Ionization and appearance potential measurements on aliphatic and ω- phenyl carbonyl compounds show that electron-impact fragmentation of these compounds α and β to the carbonyl group resulting in charge retention on the hydrocarbon fragment can occur without ionization of the carbonyl group. Structures are assigned to ionic and neutral fragments on the basis of their enthalpies, and evidence is presented favouring the elimination of the neutral enol forms of acetone and acetaldehyde in the hydrogen-rearranged β fission of ketones and aldehydes.

scholarly journals STUDYING OF CONNECTION OF HYDROCARBON FRAGMENT OF COLLECTOR WITH ITS FLOTATION ACTIVITY

2019 ◽  
Vol 2 (4) ◽  
pp. 290-294
Author(s):  
Dina Sem’yanova
Keyword(s):  
Thermodynamic Description ◽  
Surface Flow ◽  
Liquid Interface ◽  
Water Molecules ◽  
Flotation Activity ◽  
Hydrophilic Group ◽  
Physical Form ◽  
Complex Forms ◽  
Hydrocarbon Fragment

High flotation activity of collector when additional hydrophilic group is implemented in its structure of hydrocarbon fragment does not have explanation in thermodynamic description of the elementary act of flotation. An assumption is made that the presence of hydrophilic group promotes connection establishing of energetic links between hydrocarbon fragment of reagent and water molecules. As a result, speed of spreading of physical form of reagent sorption on “gas-liquid” interface, when flotation complex forms, increases. Connection between flotation activity of collector, its structure and composition and power of surface flow of its physically sorbed forms is established.

scholarly journals CHOICE OF MOLECULE STRUCTURE AND COMPOSITION BASED ON WORKING MECHANIZM OF PHYSICALLY SORBED COLLECTROR’S FORM

2019 ◽  
Vol 2 (4) ◽  
pp. 61-68
Author(s):  
Sergey Kondratyev
Keyword(s):  
Amino Acids ◽  
Surface Flow ◽  
Aliphatic Alcohols ◽  
Hydrocarbon Radical ◽  
Molecule Structure ◽  
Sulphide Ores ◽  
Conscious Choice ◽  
Choice Method ◽  
Hydrocarbon Fragment

In the paper choice method of collector’s molecule structure and composition is shown based on dependence of collecting activity of floatation reagent on power of surface flow of its physically sorbed forms. The method allows to discover influence of structure and composition specialties hydrocarbon fragment and molecule of floatation reagent-collector on extraction of useful component and quality of concentrate. Particular methods of conscious choice of structure and composition of hydrocarbon fragment of collector’s molecule in the context of some known collectors such as N-acidified amino acids, oxo acids and floatation regulators of non-sulphide ores – oxiethylized aliphatic alcohols. The influence of some structural specialties hydrocarbon radical on collecting activity of the reagent is established. These specialties are distance between carboxyl and amido groups in N-acidified amino acids, quantity of oxiethil groups and its location of in hydrocarbon fragment of alcohol or oxo acids.

Zur Photolumineszenz von Benzologen des Thiophens

1985 ◽  
Vol 40 (5) ◽  
pp. 497-502 ◽  
Author(s):  
Maximilian Zander
Keyword(s):  
Energy Gap ◽  
Heavy Atom ◽  
Phosphorescence Spectrum ◽  
Quantum Yields ◽  
Triplet States ◽  
Fluorescence And Phosphorescence Spectra ◽  
Atom Effect ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra ◽  
Hydrocarbon Fragment

Fluorescence and phosphorescence spectra, fluorescence and phosphorescence quantum yields and phosphorescence lifetimes of the benzologues I -V of thiophene have been measured in ethanol at 77 K. By comparing the energies of the lowest triplet states of the molecules with those of corresponding hydrocarbons it is concluded that the sulphur atoms act like substituents and are not equivalent to aromatic double bonds. The rate of the radiationless deactivation of the lowest triplet state depends on the energy gap Δ E(T1 - S0) in accordance with the Siebrand relation. An unexpected small intraannullar heavy-atom effect of the sulphur is observed in 2,2′-bis-benzo[b]thienyl (II), a strongly fluorescing compound. As the most likely explanation it is concluded from experiments that in II the interaction between the heavy-atom and the π-MO’s of the hydrocarbon fragment (1,4-biphenylbutadiene) is much smaller compared to that in other structurally related benzologues of thiophene. External heavy-atom perturbers (AgClO4, CH3J) have a strong influence on the vibronic structure of the phosphorescence spectrum of IV.

THE UNUSUAL ADSORPTION BEHAVIOUR OF BENZENE ON ${\rm Co}(10{\bar 1}0)$

2000 ◽  
Vol 07 (01n02) ◽  
pp. 67-74 ◽  
Author(s):  
C. J. BARNES ◽  
M. VALDEN ◽  
M. PESSA
Keyword(s):  
Ring Opening ◽  
Room Temperature ◽  
Adsorption Behaviour ◽  
Bond Scission ◽  
Hydrocarbon Fragment

Adsorption of benzene on (10[Formula: see text] leads to formation of an ordered p(3 × 1) monolayer. ARPES measurements combined with adlayer density considerations indicate that the [Formula: see text] monolayer consists of molecules whose symmetry has been reduced to C1 consistent with a partially dehydrogenated tilted cyclic C6 intermediate (phenyl or C6H4). Desorption measurements in conjunction with ARPES indicate that a stepwise dehydrogenation of the ring occurs with the dehydrogenation step above room temperature at ~ 380 K corresponding to formation of small well-oriented CxHy (x, y = 1 or 2) hydrocarbon fragment(s) (possibly C2H and CH) resulting from ring opening. Complete dehydrogenation occurs for temperatures above 550 K, leaving a carbonaceous residue. The low dehydrogenation and decomposition temperatures indicate [Formula: see text]0) to be particularly active towards both C–H bond scission and ring opening.

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