Formation of Excited Singlet States in the Nanosecond Pulse Radiolysis and Nanosecond Flash Photolysis of Aromatic Molecules in Liquid and Solid Solutions

1969 ◽  
Vol 51 (2) ◽  
pp. 770-778 ◽  
Author(s):  
J. K. Thomas
Keyword(s):  
Solid Solutions ◽  
Pulse Radiolysis ◽  
Flash Photolysis ◽  
Nanosecond Pulse ◽  
Excited Singlet ◽  
Aromatic Molecules ◽  
Singlet States ◽  
Excited Singlet States

Nanosecond Flash Photolysis and the Absorption Spectra of Excited Singlet States

Nature ◽  
1968 ◽  
Vol 220 (5173) ◽  
pp. 1228-1229 ◽  
Author(s):  
GEORGE PORTER ◽  
MICHAEL R. TOPP
Keyword(s):  
Absorption Spectra ◽  
Flash Photolysis ◽  
Excited Singlet ◽  
Singlet States ◽  
Excited Singlet States

Fluorescence and Proton Nuclear Magnetic Resonance Studies of Thallous Ions - Crown Ether Complexes in Organic Solvents

1978 ◽  
Vol 33 (6) ◽  
pp. 614-618 ◽  
Author(s):  
T. Platzner ◽  
J. K. Thomas
Keyword(s):  
Crown Ether ◽  
Pulse Radiolysis ◽  
Proton Nuclear Magnetic Resonance ◽  
Excited Singlet ◽  
Magnetic Resonance Studies ◽  
Nmr Data ◽  
Singlet States ◽  
Hydrated Electrons ◽  
Crown Ether Complexes ◽  
Excited Singlet States

Abstract The complexing of thallous ions (T1+), with the crown ether dibenzo 18 crown-6 poly-ether (DB) has been studied by NMR, fluorescence, and pulse radiolysis techniques. NMR data show a strong interaction of the T1+ ions with the aromatic moieties. This is also illustrated by a static quenching of the aromatic fluorescence by Tl+ . The rates of reactions of T1+ with hydrated electrons eaq- and pyrene excited singlet states are decreases on complexing the ion by the crown ether.

Enhanced basicity of 1,3-dialkoxy-substituted benzenes: cyclophane derivatives

1994 ◽  
Vol 72 (12) ◽  
pp. 2388-2395 ◽  
Author(s):  
Guangzhong Zhang ◽  
Yijian Shi ◽  
Renée Mosi ◽  
Thao Ho ◽  
Peter Wan
Keyword(s):  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Structural Constraints ◽  
Excited Singlet ◽  
Deuterium Incorporation ◽  
Stable Conformation ◽  
Substituted Benzenes ◽  
Singlet States ◽  
Excited Singlet States

The photoprotonation of four dialkoxy-substituted benzenes in their excited singlet states has been studied. The parent systems 4 and 5 are regioselectively photoprotonated at the 2-position, with significant quantum efficiencies for deuterium incorporation at acidities greater than pH 2. The structurally related cyclophane derivatives 6 and 7 did not show any deuterium exchange over the same acidity range but fluorescence quenching by proton (in aqueous solution) and laser flash photolysis studies (in 1,1,1,3,3,3-hexafluoro-2-propanol) indicate that photoprotonation does take place with these compounds. Due to structural constraints imposed by the most stable conformation adopted by these molecules (6 and 7), the attacking proton (deuteron) is also the proton (deuteron) that is deprotonated from the cyclohexadienyl cation (2,6-dialkoxybenzenonium ion) intermediate, resulting in the absence of incorporation of deuterium.

Nanosecond flash photolysis

1970 ◽  
Vol 315 (1521) ◽  
pp. 163-184 ◽  
Keyword(s):  
Flash Photolysis ◽  
Pulsed Laser ◽  
Triplet States ◽  
Excited Singlet ◽  
Excited Triplet ◽  
Singlet States ◽  
Time Region ◽  
Excited Singlet States ◽  
Chemical Events ◽  
Excited Triplet States

A flash photolysis system, using a pulsed laser as source, has been designed and used to study events having a duration of a few nanoseconds; an improvement over conventional flash techniques by a factor of a thousand. The apparatus incorporates both spectrographic and photoelectric monitoring techniques which are easily interchangeable and, apart from the laser itself, it is readily constructed from standard components. Its applications to the observation of the absorption spectra of excited singlet states, short-lived excited triplet states and chemical events in the nanosecond time region are described.

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