scholarly journals Quenching of hexafluoroacetone phosphorescence by mercury

1968 ◽  
Vol 46 (6) ◽  
pp. 1031-1033 ◽  
Author(s):  
N. C. Lang ◽  
K. O. Kutschke
Keyword(s):  
Triplet State ◽  
Linear Function ◽  
Excellent Agreement ◽  
Mercury Concentration ◽  
Relative Yield ◽  
Lifetime Measurements ◽  
First Order

The ratio of the relative yield for fluorescence to that for phosphorescence of hexafluoroacetone excited at 3130 Å was measured; the ratio was a linear function of mercury concentration. This observation confirms that the deactivation of the triplet state proceeds by a reaction which is first order in [Hg]. A quenching constant was obtained which is in excellent agreement with that based on lifetime measurements under mercury-free and mercury-saturated conditions.

The reaction of μ-oxo-bis(phthalocyaninato)iron(III) with hydrogen sulphide in the presence of pyridine: Evidence for axial coordination of dichloromethane

2005 ◽  
Vol 09 (03) ◽  
pp. 198-205 ◽  
Author(s):  
Fabrizio Monacelli ◽  
Elisa Viola
Keyword(s):  
Reaction Mechanism ◽  
Linear Function ◽  
Rate Constant ◽  
Hydrogen Sulphide ◽  
Stoichiometric Ratio ◽  
First Order ◽  
Axial Coordination ◽  
Elementary Sulphur ◽  
Increasing Function ◽  
Limiting Value

The oxo-bridged complex ( py ) FePc - O - FePc ( py ) ( py = pyridine , Pc = phthalocyaninato dianion) reacts in dichloromethane with hydrogen sulphide giving elementary sulphur and the reduced ( py )2( FePc ) complex in the stoichiometric ratio 1:1. Under excess py and H2S , the reaction is first-order and the rate constant at a given py concentration is an increasing function of the reducing agent concentration, with asymptotic tendency to a limiting value. This latter depends on the pyridine concentration being higher the lower is the base concentration. When the reaction is carried out in pure pyridine, the rate constant is, instead, a strictly linear function of [ H2S ], with zero intercept. A reaction mechanism is proposed where the dichloromethane is directly involved in the axial coordination about the iron centers and H2S competes efficiently with both pyridine and solvent.

COMBINATION AND DISPROPORTIONATION OF ETHYL RADICALS: INFLUENCE OF THE REACTION H+C2H5 = C2H6

1955 ◽  
Vol 33 (5) ◽  
pp. 821-829 ◽  
Author(s):  
Moyra J. Smith ◽  
Patricia M. Beatty ◽  
J. A. Pinder ◽  
D. J. Le Roy
Keyword(s):  
Light Intensity ◽  
Excellent Agreement ◽  
Mercury Concentration ◽  
Rate Constants ◽  
Room Temperature ◽  
Low Light ◽  
Ethylene Concentration ◽  
Light Intensities ◽  
Ethyl Radicals ◽  
Hydrogenation Of Ethylene

The mercury (3P1) photosensitized hydrogenation of ethylene has been studied at room temperature as a function of ethylene concentration, mercury concentration, and light intensity. In addition to combination and disproportionation, ethyl radicals have been shown to take part in the reaction[Formula: see text]The conditions favoring this reaction have been established and anomalous values previously found for the ratio of ethane to butane have been explained. The value obtained for the ratio of the rate constants for the disproportionation and combination of ethyl radicals, 0.15 ±.01, is in excellent agreement with the values obtained by other methods. Hexane formation is of some importance at low light intensities and high ethylene concentrations, and is adequately accounted for by the reactions[Formula: see text]

Mercury Concentration of White Muscle in Relation to Age, Growth, and Condition in Four Species of Fishes from Clay Lake, Ontario

1974 ◽  
Vol 31 (11) ◽  
pp. 1723-1729 ◽  
Author(s):  
D. P. Scott
Keyword(s):  
Mercury Concentration ◽  
White Muscle ◽  
Species Differences ◽  
Lake Ontario ◽  
Age And Growth ◽  
Coregonus Clupeaformis ◽  
Catostomus Commersoni ◽  
First Order ◽  
Species Area ◽  
Statistical Relationships

Studies of large (about 125) samples of walleye (Stizostedion vitreum), northern pike (Esox lucius), white sucker (Catostomus commersoni), and lake whitefish (Coregonus clupeaformis) from each of four areas of Clay Lake, Ontario, a highly mercury-contaminated lake, have confirmed previous findings that the larger the fish, the greater the white muscle mercury concentration, within species, within populations. This relationship was statistically broken into separate age:concentration and growth:concentration partial regressions; older fish and faster growing fish were generally more contaminated, subject to the above species–area restrictions. However, the generally positive correlation between concentration and condition (as measured by relative heaviness of individuals within area–species samples) found in the previous study is here contradicted; relatively heavier fish tended to have lower Hg concentrations. Despite the relatively small size of the lake (about 11 × 2 km) analyses of multiple covariance indicated profound within-species differences between the samples from the four areas. However, there did not appear to be any obvious correlation between these differences and sediment mercury values.The various statistical relationships do not appear to be simple, first-order regressions; rather, there appear to be significant interactions between age and growth, and age and condition, which tend to change the partial slopes with age. The four species were distinctly different in most of their relationships.

Temperature Dependence of Bulk Viscosity in Liquid Argon

1972 ◽  
Vol 50 (16) ◽  
pp. 1881-1886 ◽  
Author(s):  
J. A. Cowan ◽  
R. N. Ball
Keyword(s):  
Vapor Pressure ◽  
Temperature Dependence ◽  
Linear Function ◽  
Excellent Agreement ◽  
Bulk Viscosity ◽  
Shear Viscosity ◽  
Saturated Vapor Pressure ◽  
Saturated Vapor ◽  
Liquid Argon ◽  
Theoretical Results

Attenuation measurements have been made on liquid argon for temperatures between 90 and 150 °K and pressures between saturated vapor and 1000 p.s.i. Values of bulk viscosity were calculated and compared with theoretical results. For densities above 1.15 gcm−3 the PNM theory is in excellent agreement. However, below these values the theoretical results continue to decrease with density where the experimental results increase sharply. The values of the ratio of bulk to shear viscosity for saturated vapor pressure are found to be a linear function of (Tc–T)−3/2 from 90 to 140 °K.

Absorption oscillator strengths to autoionizing states in Li, N, and F and their isoelectronic sequences

1976 ◽  
Vol 54 (6) ◽  
pp. 689-694 ◽  
Author(s):  
Donald R. Beck ◽  
Cleanthes A. Nicolaides
Keyword(s):  
Excellent Agreement ◽  
Order Theory ◽  
Oscillator Strengths ◽  
First Order ◽  
First Order Theory ◽  
Electron Transitions ◽  
The One ◽  
Beam Foil ◽  
Autoionizing States ◽  
Electron Interactions

We have calculated the photoabsorption oscillator strengths of the one and two-electron transitions Li 1s22s2S → 2s22p2P0, NI 2s22p32P0 → 2s2p42D, NI 2s22p32D0 → 2s2p42D, and FI 2s22p52P0 → 2s2p62S, whose upper states are autoionizing, according to a new first order theory of oscillator strengths (FOTOS). These oscillator strengths are often very small and are sensitive to the details of electron–electron interactions. Also computed are the f values for ions in the N and F isoelectronic sequences. Comparison of our theory with three very recent beam-foil values in OII, FIII, and NeII shows excellent agreement.

Effect of Temperature and Viscosity on the True First Order Decay of the Triplet State of Aromatic Molecules

2010 ◽  
Vol 71 (11-12) ◽  
pp. 641-641 ◽  
Author(s):  
George Porter ◽  
Louis J. Stief
Keyword(s):  
Triplet State ◽  
Effect Of Temperature ◽  
First Order ◽  
Aromatic Molecules

scholarly journals Large-scale Subspace Clustering by Fast Regression Coding

2017 ◽  
Author(s):  
Jun Li ◽  
Handong Zhao ◽  
Zhiqiang Tao ◽  
Yun Fu
Keyword(s):  
Linear Function ◽  
Spectral Clustering ◽  
Large Scale ◽  
Order Approximation ◽  
Subspace Clustering ◽  
Low Rank ◽  
First Order ◽  
Non Linear ◽  
Data Points ◽  
First Order Approximation

Large-Scale Subspace Clustering (LSSC) is an interesting and important problem in big data era. However, most existing methods (i.e., sparse or low-rank subspace clustering) cannot be directly used for solving LSSC because they suffer from the high time complexity-quadratic or cubic in n (the number of data points). To overcome this limitation, we propose a Fast Regression Coding (FRC) to optimize regression codes, and simultaneously train a non-linear function to approximate the codes. By using FRC, we develop an efficient Regression Coding Clustering (RCC) framework to solve the LSSC problem. It consists of sampling, FRC and clustering. RCC randomly samples a small number of data points, quickly calculates the codes of all data points by using the non-linear function learned from FRC, and employs a large-scale spectral clustering method to cluster the codes. Besides, we provide a theorem guarantee that the non-linear function has a first-order approximation ability and a group effect. The theorem manifests that the codes are easily used to construct a dividable similarity graph. Compared with the state-of-the-art LSSC methods, our model achieves better clustering results in large-scale datasets.

The kinetics and mechanism of the reaction between nickel(II) and dithiocarbamate ions in dimethyl sulfoxide. Evidence for the ID mechanism for a bidentate uninegative ligand

1978 ◽  
Vol 31 (12) ◽  
pp. 2581 ◽  
Author(s):  
PJ Nichols ◽  
MW Grant
Keyword(s):  
Fourier Transform ◽  
Ionic Strength ◽  
Dimethyl Sulfoxide ◽  
Excellent Agreement ◽  
Rate Constants ◽  
Second Order ◽  
Kinetics And Mechanism ◽  
First Order ◽  
Temperature Dependences ◽  
Mechanism Of The Reaction

13C Fourier-transform N.M.R. has been used to measure the rate of exchange of dimethyl sulfoxide with hexakis(dimethyl sulfoxide)nickel(II) cation. The parameters obtained, kex(25°C)(9.8�4.6) × 103 s-1, ΔH‡ 50�2 kJ mol-1 and ΔS‡ 0�4 J K-1 mol-1, are in excellent agreement with those of the most recent 1H N.M.R. study. The reaction between Ni(Me2SO)62+ and diethyldithiocarbamate (dtc-) gives only Ni(dtc)2. When dtc- is in excess, the rate of formation of Ni(dtc)2 is first order in Ni2+ and dtc-. The ionic-strength and temperature dependences of the second-order rate constants are consistent with the rate-determining formation of an unstable Ni(dtc)+ complex by an ID mechanism.

Triplet‐Singlet Transitions in Organic Molecules. Lifetime Measurements of the Triplet State

1949 ◽  
Vol 17 (10) ◽  
pp. 905-913 ◽  
Author(s):  
Donald S. McClure
Keyword(s):  
Triplet State ◽  
Organic Molecules ◽  
Lifetime Measurements

Viscosity Dependence of the First‐Order Decay of the Triplet State of Anthracene and Related Molecules

1963 ◽  
Vol 39 (10) ◽  
pp. 2593-2598 ◽  
Author(s):  
Robert Livingston ◽  
William R. Ware
Keyword(s):  
Triplet State ◽  
First Order ◽  
Viscosity Dependence
Sign in / Sign up

Export Citation Format

Share Document