The radiation-induced formation of excited states of aromatic hydrocarbons in benzene and cyclohexane I. Radiation induced fluorescence from solutions of aromatic hydrocarbons in cyclohexane

1972 ◽  
Vol 328 (1575) ◽  
pp. 445-456 ◽  
Keyword(s):  
Nitrous Oxide ◽  
Excited States ◽  
Aromatic Hydrocarbons ◽  
Rate Constants ◽  
Pulse Radiolysis ◽  
Singlet State ◽  
Sulphur Hexafluoride ◽  
Excited Singlet ◽  
Recombination Processes ◽  
Radiation Induced

The nature of radiation-induced fluorescence from solutions of anthracene, naphthalene and pyrene in cyclohexane has been investigated. Evidence is presented for the formation of excited singlet solute molecules via charge recombination processes. Rate constants, measured by the pulse radiolysis technique, are reported for the quenching of excited singlet state molecules of naphthalene and pyrene by oxygen, xenon, iodine, 1,3-cyclohexadiene, nitrous oxide, sulphur hexafluoride and nitromethane.

The radiation-induced formation of excited states of aromatic hydrocarbons in benzene and cyclohexane, II. Yields of excited singlet and triplet state solute molecules

1972 ◽  
Vol 328 (1575) ◽  
pp. 457-479 ◽  
Keyword(s):  
Excited States ◽  
Pulse Radiolysis ◽  
Singlet State ◽  
Relative Yield ◽  
Excited Singlet State ◽  
High Yield ◽  
Triplet States ◽  
Excited Singlet ◽  
Concentration Dependences ◽  
Radiation Induced

The concentration dependences of the yield of excited triplet states, G ( 3 S*), and the concentration dependences of the relative yield of radiation-induced fluorescence obtained on pulse radiolysis of solutions of naphthalene, anthracene, pyrene and 2,5-diphenyloxazole (PPO) are reported. The yields of excited singlet state solute molecules, G ( 1 S*), formed on pulse radiolysis of naphthalene-cyclohexane and naphthalene-benzene solutions has been determined by comparing the intensity of the radiation-induced fluorescence with that obtained on photo-excitation. It is concluded that intersystem crossing (i.s.c.) from the excited singlet state is an important process in the formation of the high yield of triplet excited states of the solute. Under certain conditions this process accounts for up to 50 % of G ( 3 S*) in cyclohexane and the entire G ( 3 S*) in benzene solutions.

The radiation-induced formation of excited states of aromatic hydrocarbons in benzene and cyclohexane. III. Effect of singlet state quenchers

1972 ◽  
Vol 328 (1575) ◽  
pp. 481-496 ◽  
Keyword(s):  
Triplet State ◽  
Excited States ◽  
State Formation ◽  
Aromatic Hydrocarbons ◽  
Extinction Coefficient ◽  
Singlet State ◽  
Excited Singlet State ◽  
Intersystem Crossing ◽  
Excited Singlet ◽  
Radiation Induced

The contribution to naphthalene and pyrene triplet state formation of intersystem crossing from the excited singlet state has been determined for both cyclohexane and benzene solutions using the singlet state quenchers nitromethane and xenon. In agreement with the conclusions reported in part II, intersystem crossing plays an important role; under certain conditions up to 50 % of the total triplet yield in naphthalene-cyclohexane solutions has this origin. The extinction coefficient for naphthalene triplet absorption in cyclohexane at λ max = 412.5 nm is 20 000 ± 5000 1 mol -1 cm -1 .

The radiation-induced formation of excited states of aromatic hydrocarbons in alicyclic hydrocarbons I. Yields of excited singlet and triplet state solute molecules

1975 ◽  
Vol 347 (1648) ◽  
pp. 61-73 ◽  
Keyword(s):  
Energy Transfer ◽  
Excited States ◽  
Pulse Radiolysis ◽  
Minor Role ◽  
Intersystem Crossing ◽  
Excited Singlet ◽  
Excited Triplet ◽  
Upper Limit ◽  
Radiation Induced ◽  
A Minor

The dependences on concentration of the yield of excited triplet naphthalene, G ( 3 Naph٭), and of the radiation-induced fluorescence obtained on pulse radiolysis of solutions of naphthalene in cyclopentane, cyclooctane and decalin are reported. The yields of singlet excited naphthalene, G( 1 Naph٭), formed on pulse radiolysis of these solutions have been determined by comparing the intensity of the radiation-induced fluorescence with that obtained on photo excitation and the extent of formation of 3 Naph٭ by intersystem crossing, G ( 3 Naph٭) i. s. c., is assessed. Upper limit yields of solvent excited states, G ( 1 RH٭), were determined by measuring the extent of singlet energy transfer to toluene. It is concluded that energy transfer from solvent excited states plays a minor role in the formation of excited states of aromatic solutes.

Studies of radiation-induced reactions of ethylene in aqueous solution II. Reactions in the presence of oxygen as studied by pulse radiolysis and γ -irradiation techniques

1967 ◽  
Vol 300 (1463) ◽  
pp. 443-454 ◽  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Rate Constants ◽  
Pulse Radiolysis ◽  
Major Product ◽  
Peroxy Radicals ◽  
Ferrous Ions ◽  
Constant Composition ◽  
Γ Irradiation ◽  
Radiation Induced

The radiolysis of dilute aqueous solutions containing ethylene and oxygen has been investigated. Pulse radiolysis was used to measure the rate constants for the addition of hydroxyl radicals to ethylene, the binary decomposition of the resulting hydroxyethyl radicals and their addition to ethylene and reaction with oxygen to yield peroxy radicals. The rate constants have also been determined for the mutual interaction of the peroxy radicals and their reaction with ferrous ions. The principal products of γ -irradiation were aldehydes and organic hydroperoxides. Hydrogen peroxide was found in yields close to the molecular yield from water. The polymer produced in the absence of oxygen was not formed, and glycollaldehyde, reported as a major product by previous workers, could not be detected. At constant composition of the gas mixtures, product yields were unaffected by total pressure in the range up to 40 atm, but were strongly dependent on the proportion of oxygen. Aldehyde yields were markedly greater at pH 1.2 than in neutral solution. The influence of ferrous ions an d of added hydrogen peroxide has been determined. The pulse radiolysis and γ -irradiation experiments complement one another and show that the radiation-induced oxidation of ethylene in aqueous solution involves the same primary reactions as occur in the absence of oxygen, followed by the formation and further reactions of peroxy radicals.

Comparative Study of the Solid-Matrix Luminescence Properties of Perdeuterated Phenanthrene and Phenanthrene Adsorbed on Several Solid Matrices

1996 ◽  
Vol 50 (9) ◽  
pp. 1140-1144 ◽  
Author(s):  
Savakkattupalayam M. Ramasamy ◽  
Robert J. Hurtubise
Keyword(s):  
Rate Constants ◽  
Singlet State ◽  
Luminescence Properties ◽  
Solid Matrix ◽  
Deuterium Isotope Effect ◽  
Excited Singlet ◽  
Excited Triplet ◽  
Wide Range ◽  
Solid Matrices ◽  
Effects Of Temperature

Temperature was varied over a wide range to determine its effect on the luminescence properties of deuterated phenanthrene and phenanthrene adsorbed on a number of solid matrices. Not only were insights into the effects of temperature and solid matrices on the luminescence properties acquired but also the deuterium isotope effect revealed unique information about the role played by the solid matrix in the luminescence of the model compounds. In addition, comparisons of nonradiative rate constants and the efficiencies of intersystem crossing revealed important differences among the solid matrices in altering these parameters. The perdeuterated phenanthrene and phenanthrene proved to be useful probes for investigating the effects of solid matrices on the excited triplet state of phosphors because the excited singlet state of the lumiphor was affected very little by the solid matrices, and the rate constants of phosphorescence for the two phosphors are essentially the same.

A NEW BAND SYSTEM OF THE P2 MOLECULE ANALOGOUS TO THE LYMAN–BIRGE–HOPFIELD BANDS OF N2

1958 ◽  
Vol 36 (5) ◽  
pp. 565-570 ◽  
Author(s):  
A. E. Douglas ◽  
K. Suryanarayana Rao
Keyword(s):  
Excited States ◽  
Ground State ◽  
Singlet State ◽  
Band System ◽  
Excited Singlet State ◽  
Lower State ◽  
High Dispersion ◽  
Electron Configuration ◽  
Excited Singlet ◽  
New System

Five bands of a new band system of P2 have been photographed at high dispersion and analyzed. The upper state of the system is a 1П0 state and lies lower than any previously known excited singlet state. The lower state of the new system is the ground state of P2 and the analysis of the new bands has given improved constants for this state. The new system appears to be the analogue of the Lyman–Birge–Hopfield bands of N2. The electron configuration of the low excited states of P2 and of related molecules is discussed.

The absorption spectrum of gaseous aluminium monofluoride in the Schumann region

1954 ◽  
Vol 224 (1156) ◽  
pp. 134-140 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Excited States ◽  
Singlet State ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Singlet Band

The absorption spectrum of gaseous aluminium monofluoride has been examined in the region 1250 to 2000 Ǻ. Six new singlet band-systems have been found. Four of the excited states have also been observed in emission in transitions to the lowest excited singlet state A 1 п, at longer wave-lengths. The energies and products of dissociation of some of the states are considered.

Wavelength Dependent and Adiabatic Photochemistry of Endoperoxides of Aromatic Hydrocarbons

1982 ◽  
Vol 37 (1) ◽  
pp. 55-57 ◽  
Author(s):  
R. Schmidt ◽  
W. Drews ◽  
H.-D. Brauer
Keyword(s):  
Aromatic Hydrocarbons ◽  
Singlet State ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Photochemical Behaviour ◽  
Photochemical Cleavage

Abstract The photochemical cleavage of the endoperoxides of anthradichromene and benzodixanthene into the parent hydrocarbon and oxygen is shown to be an adiabatic photoreaction originating from an upper excited singlet state. This photochemical behaviour is described by a theory for the photochemistry of endoperoxides developed by Kearns and Khan.

Substituenteneffekte im spektroskopischen Verhalten von Maleinsäurederivaten und 4-Cyclopenten-1.3-dionen / Substituent Effects on the Spectroscopic Behavior of Maleic Acid Derivatives and 4-Cyclopentene-1,3-diones

1973 ◽  
Vol 28 (9-10) ◽  
pp. 662-681 ◽  
Author(s):  
Hans-Dieter Scharf ◽  
Hans Leismann
Keyword(s):  
Excited States ◽  
Maleic Acid ◽  
Singlet State ◽  
Substituent Effects ◽  
Quantum Yields ◽  
Mo Calculations ◽  
Excited Singlet ◽  
Inductive Effects ◽  
Phosphorescence Emission ◽  
Spectroscopic Behavior

The lowest excited states of maleic acid- and cyclopentendionderivatives have been investigated by UV-absorption and phosphorescence emission spectroscopy. While the first excited singlet-state S1 is of 1(nπ*)-type in all compounds, the lowest triplet-state T1 was found to be a mixture of 3(nπ*) and 3(ππ*)-configurations. For the emitting derivatives (Ζ ≠ Η) phosphorescence-lifetimes and -quantum yields as well as the probability for intersystem crossing have been determined.Considering the inductive effects of all substituents on the S1 (nπ*) -energy, Coulombpotentials for sulfur and iodine in terms of Huckel-parameters: hs = 0,2 and hj = —0,5 have been derived.The results of Hückel-MO-calculations can be correlated to the measured values of all compounds with the exception of the iodine containing derivatives.

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