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 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. 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.

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.

Violation of Hund's multiplicity rule in the electronically excited states of conjugated hydrocarbons

1985 ◽  
Vol 63 (7) ◽  
pp. 1572-1579 ◽  
Author(s):  
Shiro Koseki ◽  
Takeshi Nakajima ◽  
Azumao Toyota
Keyword(s):  
Triplet State ◽  
Excited States ◽  
Singlet State ◽  
Basis Set ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Electronically Excited States ◽  
Conjugated Hydrocarbons ◽  
Electronically Excited ◽  
Linear Polyenes

Violation of Hund's multiplicity rule in the electronically excited states of conjugated hydrocarbons is studied by using the Pariser–Parr–Pople type SCF MO method and the abinitio MO method with STO-3G basis set, both methods being augmented by CI-type treatments. It is shown that for symmetrical structures (D2h) of the nonalternant hydrocarbons, propalene, pentalene, and heptalene, the lowest excited singlet state is energetically lower than the corresponding triplet state. This is mainly due to the spin polarization (SP) effects. For D2h, structures of pentalene and heptalene the open-shell excited singlet state is predicted to be lower in energy than the closed-shell state, with the result that the former is really the ground state. Further, calculations made by including electron correlation effects reveal that in linear polyenes and polyacenes, the lowest excited singlet "minus" state (using Pariser's classification of the alternancy symmetry species) is lower in energy than the corresponding triplet state. The energy lowering of the singlet "minus" state in linear polyenes is due mostly to the mixing with the doubly excited configurations (mm → nn), while the considerable part of it in polyacenes is due to the SP effects.

Experimentelle und Quantenchemische Untersuchungen der Dipolmomente von Substituierten Stilbenen im Ersten Angercgten Singulettzustand / Experimental and Quantum Chemical Investigations of Dipole Moments of Substituted Stilbens in the First Excited Singlet State

1977 ◽  
Vol 32 (5) ◽  
pp. 420-425 ◽  
Author(s):  
A. Kawski ◽  
I. Gryczyński
Keyword(s):  
Dipole Moment ◽  
Excited States ◽  
Ground State ◽  
Quantum Chemical ◽  
Singlet State ◽  
Dipole Moments ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Fluorescent State ◽  
Experimental Values

Abstract The values a/a3 (α = polarizability), the Onsager cavity radii a and the dipole moments μe of six substituted stilbens in the fluorescent state have been determined. It is shown that if the dipole moment of the lowest excited singlet state μe is parallel to the dipole moment in the ground state μg, the values of μe and a can be determined from the solvent effects. Moreover, quantum chemical investigations of the dipole moments in the ground and excited states were carried out with the Pariser-Parr-Pople method and compared with the experimental values.

Base strengths of substituted 2- and 4-styrylpyridines in the ground and excited states

1969 ◽  
Vol 47 (13) ◽  
pp. 2355-2359 ◽  
Author(s):  
J. C. Doty ◽  
J. L. R. Williams ◽  
P. J. Grisdale
Keyword(s):  
Excited States ◽  
Ground State ◽  
Singlet State ◽  
Excited Singlet State ◽  
Hammett Equation ◽  
Excited Singlet

The base strengths of various 2- and 4-styrylpyridines in the ground state and first-excited-singlet state have been determined. The base strengths are found to conform to the Hammett equation if the proper σ values are chosen.

Structure and Energy Spectra of Molecules Containing Anti-Aromatic Ring Systems. IV. Aromaticity and Anti-Aromaticity in Electronic Ground and Excited States

1997 ◽  
Vol 52 (9) ◽  
pp. 1072-1076 ◽  
Author(s):  
Fritz Dietz ◽  
Henryk Vogel ◽  
Anna Schleitzer ◽  
Nikolai Tyutyulkov ◽  
Mordecai Rabinovitz
Keyword(s):  
Aromatic Ring ◽  
Excited States ◽  
Singlet State ◽  
Excited Singlet State ◽  
Energy Spectra ◽  
Excited Singlet ◽  
Ring Systems ◽  
Electronic Ground

Using various criteria to characterize the terms aromaticity and anti-aromaticity it is shown that the non-benzoid aromatic azulene and the benzoid aromatic naphthalene should have anti-aromatic properties in the first excited singlet state.

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