Spectroscopy in the Ultraviolet and Visible Regions As Studied by Solution-Phase and Vapor-Phase Photoabsorption in the Ultraviolet and Visible Regions†

1996 ◽  
Vol 15 (22) ◽  
pp. 4747-4754 ◽  
Author(s):  
Jennifer C. Green ◽  
Sergey Yu. Ketkov
Keyword(s):  
Vapor Phase ◽  
Solution Phase

The relative rates of bromination of cyclohexane and cyclopentane with molecular bromine. Comparison of the reactions in solution and in vapor phase

1981 ◽  
Vol 59 (9) ◽  
pp. 1368-1374 ◽  
Author(s):  
Dennis D. Tanner ◽  
Tomoki C-S. Ruo ◽  
Hideki Takiguchi ◽  
Andre Guillaume
Keyword(s):  
Vapor Phase ◽  
Hydrogen Bromide ◽  
Bromine Atom ◽  
Relative Rate ◽  
Solution Phase ◽  
Molecular Bromine ◽  
Transfer Rates ◽  
Relative Rate Constants ◽  
Halogenated Alkanes ◽  
Relative Transfer

The relative rates of transfer of the cyclopentyl radical with molecular bromine and hydrogen bromide (k2′/k−1′) and with hydrogen tribromide and hydrogen bromide (k3′/k−1′) have been determined. The relative transfer rates are compared with the analogous values previously reported for the reactions of cyclohexyl radicals (k2/k−1 and k3/k−1). Utilizing the values of k2′/k−1 and k2/k−1 the competitive vapor phase rates of bromine atom abstraction of hydrogen from the two substrates could be obtained. An expression using a combination of the five sets of relative rate constants was used to determine the effect of competitive cage reversal which occurs in the solution phase bromination of the two substrate radicals with caged hydrogen bromide. For two structurally similar radicals, cage reversal (internal return) was found to affect the relative rates of bromination by 30%, while the relative transfer rates, although differing each by a factor of two, fortuitously nearly cancel each other's effect.The effect of both internal and external reversal reactions on the relative rates of bromination of structurally dissimilar substrates, halogenated alkanes and their parent hydrocarbons, is discussed.

Vapor-phase and solution-phase UV spectroscopic studies of η5-pentadienyl derivatives of iron and ruthenium

1998 ◽  
Vol 563 (1-2) ◽  
pp. 209-217 ◽  
Author(s):  
Sergey Yu Ketkov ◽  
Richard D Ernst ◽  
Lothar Stahl ◽  
Wimonrat Trakarnpruk
Keyword(s):  
Vapor Phase ◽  
Spectroscopic Studies ◽  
Solution Phase ◽  
Derivatives Of

A reinvestigation of the vapor phase bromination of 2-bromobutane

1984 ◽  
Vol 62 (11) ◽  
pp. 2310-2316 ◽  
Author(s):  
Dennis D. Tanner ◽  
Tomoki C. S. Ruo ◽  
Yoshio Kosugi ◽  
Alan Potter
Keyword(s):  
Vapor Phase ◽  
Thermal Instability ◽  
Addition Reaction ◽  
Bromine Atom ◽  
Solution Phase ◽  
Reaction Schemes

The solution phase photobromination of 2-bromobutane yields 2,2-dibromobutane, meso-2,3-dibromobutane, dl-2,3-dibromobutane, small amounts of 1,2-dibromobutane, and 2,2,3-tribromobutane. However, in the corresponding vapor phase bromination these products appear along with other polybrominated products. The yield of these polybromides increases with temperature. The increase in yield of the polyhalogenated materials is rationalized by considering the thermal instability of the β-bromoalkyl radical, which eliminates a bromine atom to form the corresponding alkene. It is demonstrated that in the vapor phase allylic bromination competes successfully with bromine addition. Reaction schemes are suggested to explain the formation of polybromides. An explanation is also offered for the discrepancy between these results and those of previously reported vapor phase work.

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

Transition alpha structure in beta-isomorphous Nb-Hf alloys

1987 ◽  
Vol 45 ◽  
pp. 232-233
Author(s):  
R.W. Carpenter ◽  
Changhai Li ◽  
David J. Smith
Keyword(s):  
Solid Solution ◽  
Solution Phase ◽  
Miscibility Gap ◽  
Large Strains ◽  
Solid Solution Phase ◽  
Two Phase ◽  
Diffuse Intensity ◽  
Metastable Form ◽  
The Matrix ◽  
Equilibrium Morphology

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.

191. Planar Waveguide Interferometers for Vapor Phase Sensing

1999 ◽  
Author(s):  
C. Joseph ◽  
D. Campbell ◽  
J. Suggs ◽  
J. Moore ◽  
N. Hartman
Keyword(s):  
Vapor Phase ◽  
Planar Waveguide
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