Concerning the spectra and solvation process of electrons in liquid butanols

1978 ◽  
Vol 56 (17) ◽  
pp. 2305-2312 ◽  
Author(s):  
Kiyoshi Okazaki ◽  
Gordon R. Freeman
Keyword(s):  
Absorption Band ◽  
Low Temperatures ◽  
Reaction Times ◽  
Optical Absorption Spectra ◽  
Isobutyl Alcohol ◽  
Temperature Coefficients ◽  
Spectral Changes ◽  
Electron Migration ◽  
Arrhenius Temperature ◽  
Short Times

The optical absorption spectra of electrons injected into the isomeric butanols settle into that of the equilibrium solvated state at rates that decrease in the order 1-butanol > isobutyl alcohol > 2-butanol at a given temperature. The relative rates reflect the dipolar reorientation times in the liquids. The Arrhenius temperature coefficients of the rates of spectral changes are ∼30 kJ/mol. The distribution of dipolar reorientation times overlaps that of geminate reaction times of the charges in an irradiated alcohol, so a significant fraction of the electrons undergoes geminate reaction before they are able to become fully solvated. At T < 200 K the fraction increases with decreasing temperature. The concurrence of the solvation process and geminate reaction implies that the former involves, at least in part, electron migration from shallower to deeper traps.There is an indication of structure in the absorption band at low temperatures and short times. The infrared peak converts to one with a maximum at ∼780 nm. The latter slides gradually into the shape of the spectrum of the equilibrium solvated state.For the spectra of the equilibrium solvated state, the energies at the absorption maxima are given by Eεmax (eV) = 3.10 − 0.0038T in isobutyl alcohol and 2.93 − 0.00447 in 2-butanol, between 170 and 300 K. The respective band widths at half heights are 1.53 ± 0.04 and 1.59 ± 0.04 eV, independent of temperature within an uncertainty of 1 meV/K.

scholarly journals Ultrasound-promoted organocatalytic enamine–azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones

2017 ◽  
Vol 13 ◽  
pp. 694-702 ◽  
Author(s):  
Gabriel P Costa ◽  
Natália Seus ◽  
Juliano A Roehrs ◽  
Raquel G Jacob ◽  
Ricardo F Schumacher ◽  
...  
Keyword(s):  
Reaction Times ◽  
Cycloaddition Reactions ◽  
Reaction Conditions ◽  
Keto Esters ◽  
Efficient Access ◽  
High Yields ◽  
Short Times

The use of sonochemistry is described in the organocatalytic enamine–azide [3 + 2] cycloaddition between 1,3-diketones and aryl azidophenyl selenides. These sonochemically promoted reactions were found to be amenable to a range of 1,3-diketones or aryl azidophenyl selenides, providing an efficient access to new ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones in good to excellent yields and short reaction times. In addition, this protocol was extended to β-keto esters, β-keto amides and α-cyano ketones. Selanyltriazoyl carboxylates, carboxamides and carbonitriles were synthesized in high yields at short times of reaction under very mild reaction conditions.

Cation mobility in gaseous, critical, and liquid deuterated methanes

1988 ◽  
Vol 66 (8) ◽  
pp. 1872-1876 ◽  
Author(s):  
M. Antonio Floriano ◽  
Norman Gee ◽  
Gordon R. Freeman
Keyword(s):  
Ion Mobility ◽  
Critical Region ◽  
Coexistence Curve ◽  
Number Density ◽  
Experimental Conditions ◽  
Gas Density ◽  
Cation Mobility ◽  
Temperature Coefficients ◽  
Arrhenius Temperature ◽  
Field Strengths

Cation mobilities µ have been measured in the deuterated methanes CHxD4−x (x = 0–4) at field strengths E/n < 4 × 10−21 V m2/molecule, 92 ≤ T/K ≤ 598 and 0.025 ≤ n/1026 molecules m−3 ≤ 171. The mobility in the equilibrium fluids was the same at a given number density n for all five methanes. In the liquid the mobility decreased as the critical region was approached. Changes in nµ in the nonsaturated gases reflected changes in clustering, which was favored at lower T or higher n. The Arrhenius temperature coefficients of ion mobilities at constant gas density near the vapor/liquid coexistence curve nearly equalled those of electron mobilities at similar experimental conditions. The ion mobility in the saturated gas was determined mainly by density and in the liquid by the viscosity.

Optical absorption spectra of LiI crystals irradiated at low temperatures

1980 ◽  
Vol 33 (2) ◽  
pp. 195-197 ◽  
Author(s):  
S. Hashmoto ◽  
Z. Maekawa ◽  
K. Atobe ◽  
M. Nakagawa
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Low Temperatures ◽  
Optical Absorption Spectra

THE INFLUENCE OF LOW TEMPERATURES ABOVE FREEZING UPON THE RATE OF AUTOLYTIC AND BACTERIAL DECOMPOSITION OF HADDOCK MUSCLE

1932 ◽  
Vol 7 (1) ◽  
pp. 147-163
Author(s):  
ERNEST HESS
Keyword(s):  
Low Temperatures ◽  
Practical Application ◽  
Bacterial Growth Rate ◽  
Fresh Fish ◽  
Ordinary Life ◽  
Temperature Coefficients ◽  
Basic Nitrogen ◽  
Bacterial Decomposition ◽  
Crushed Ice ◽  
Number Of Bacteria

The influence of temperature upon autolytic and bacterial decomposition of haddock muscle within the range of 36 to 30° F. (+2.2 to −1.1 °C.) has been followed by determining the increase in the amount of volatile basic nitrogen parallel with the increase in the number of bacteria. A mixed flora of bacteria normally occurring on haddock was used for inoculation purposes. The experimental results show that practically no autolysis takes place at these temperatures, and that the bacterial decomposition and bacterial growth rate at 30° F. is only about half of that at 36° F. Expressed in mathematical terms, it was found that the temperature coefficients (Q10) for these reactions during the phases of logarithmic increase were considerably higher than the values for Q10 for ordinary life processes at medium temperatures (Q10 = 2 to 3, van't Hoff). The values for Q10 increased rapidly with decreasing temperature range. The practical application of these findings has been demonstrated to be of economical importance in the holding of fresh fish at 30° F. instead of the customary holding in crushed ice at about 36° F.

The Master Equation for the Dissociation of a Dilute Diatomic Gas. X. How Rotation Causes Low Arrhenius Temperature Coefficients

1973 ◽  
Vol 51 (18) ◽  
pp. 3152-3155 ◽  
Author(s):  
Huw O. Pritchard
Keyword(s):  
Low Temperature ◽  
Temperature Coefficient ◽  
Rate Constants ◽  
Recombination Rate ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Equilibrium Form ◽  
Temperature Coefficients ◽  
Recombination Rate Constant ◽  
Arrhenius Temperature

It is shown that previously calculated nonequilibrium rate constants for the dissociation of H2 and D2 appear to approach a rotationally averaged equilibrium expression at low temperature. This equilibrium form of the rate expression itself has an Arrhenius temperature coefficient for dissociation which is significantly less than the dissociation energy, and the corresponding recombination rate constant has a negative temperature coefficient. The reasons for this are explained.

Electronic properties of the actinide metals at low temperatures

1963 ◽  
Vol 276 (1367) ◽  
pp. 553-570 ◽  
Keyword(s):  
Electrical Resistivity ◽  
Low Temperatures ◽  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Al Alloys ◽  
Positive Temperature ◽  
Positive Coefficient ◽  
Disorder Effects ◽  
Temperature Coefficients ◽  
Spin Disorder

The electrical resistivity and thermoelectric power of thorium, uranium, neptunium and plutonium have been measured down to liquid-helium and liquid-hydrogen temperatures. The resistivities are relatively high, especially those of neptunium and plutonium, while all the thermoelectric powers show complicated temperature relations. The temperature dependence of the resistance of a-plutonium is abnormal, being characterized by a small negative temperature coefficient above 105 °K and a large positive coefficient below this temperature. Some plutonium rich d-Pu + Al alloys also show similar behaviour. An explanation in terms of spin-disorder effects seems most reasonable, and it is suggested that both a- and d-plutonium may be antiferromagnetic. The resistance—temperature curves of uranium and neptunium also are unusual in that the positive temperature coefficients decrease monotonically with rising temperature. Possible reasons for this have been discussed.

Comparative Viscometric Studies of Solutions of Crepe Rubber and of Buna

1938 ◽  
Vol 11 (2) ◽  
pp. 372-382 ◽  
Author(s):  
W. Philippoff
Keyword(s):  
Natural Rubber ◽  
Temperature Coefficient ◽  
Low Temperatures ◽  
Distribution Curve ◽  
Small Temperature ◽  
Flow Curves ◽  
Temperature Coefficients ◽  
Insight Into

Abstract Measurements and their representation as flow curves of solutions of Buna-115 in tetrachloroethane give a means of obtaining an insight into the properties of Buna-115 in solution. By measurements of the viscosity as a function of temperature, it was proved that the temperature coefficient is similar in magnitude to that of natural rubber and that of polystyrene. A comparison of the flow curves of Buna, masticated rubber, pyroxylin, and Cellit leads to certain conclusions regarding the elasticity of colloids in solution and the role of the distribution curve. At low temperatures, i. e., below −40° C., both Buna and natural rubber show transformation points, which are manifest by increases in the otherwise very small temperature coefficients. The measurements reveal no property of natural rubber and of Buna which is peculiar to these two substances alone.

Optical Absorption Spectra of Phosphonyl Radicals

1984 ◽  
Vol 39 (5) ◽  
pp. 434-436 ◽  
Author(s):  
T. Sumiyoshi ◽  
A. Henne ◽  
P. Lechtken ◽  
W. Schnabel
Keyword(s):  
Free Radicals ◽  
Absorption Band ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
General Structure ◽  
Laser Flash ◽  
Type I ◽  
Phosphine Oxides ◽  
Optical Absorption Spectra ◽  
Strong Absorption Band

Upon UV-irradiation, various phosphine oxides of the general structure I were found to be fragmented readily into free radicals I′ and I″ Laser flash photolysis studies revealed that radicals of type I" with R2 and/or R3 being phenyl groups possess a strong absorption band with a maximum around 330 nm. ε335nm= 1.9×104 1/mol cm was estimated for diphenyl phosphonyl radicals (Ph2P = O).

On the Origin of EL2 Intracenter Absorption Band in GaAs

1987 ◽  
Vol 104 ◽  
Author(s):  
M. Skowronski
Keyword(s):  
Absorption Band ◽  
Optical Absorption ◽  
Absorption Spectra ◽  
Conduction Band ◽  
Metastable State ◽  
Uniaxial Stress ◽  
Alternative Interpretation ◽  
Optical Absorption Spectra ◽  
Wide Absorption Band ◽  
Dx Center

ABSTRACTAn alternative interpretation of optical absorption spectra due to intracenter transition within EL2 defect in GaAs is provided. The arguments are presented that states originating from the L-valley of the conduction band can account for the presence of the wide absorption band, the no-phonon line and the observed uniaxial stress splittings. Using the analogy to the DX center, this model presents an explanation for the existence of the metastable state of EL2.

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