Excited state and free radical properties of Rhodamine 123: a laser flash photolysis and radiolysis study

1999 ◽  
Vol 1 (2) ◽  
pp. 261-268 ◽  
Author(s):  
M W. Ferguson ◽  
P C. Beaumont ◽  
S E. Jones ◽  
S Navaratnam ◽  
B J. Parsons
Keyword(s):  
Excited State ◽  
Free Radical ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Rhodamine 123

Photophysics of Tungsten and Molybdenum Arylcarbyne Complexes. Observation of the Lowest Excited State by Laser Flash Photolysis

1996 ◽  
Vol 35 (26) ◽  
pp. 7769-7775 ◽  
Author(s):  
Thomas K. Schoch ◽  
Andrea D. Main ◽  
Richard D. Burton ◽  
Lucian A. Lucia ◽  
Edward A. Robinson ◽  
...  
Keyword(s):  
Excited State ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash

Exploratory study of the quenching of photosensitizers by initiators of free radical "living" polymerization

1997 ◽  
Vol 75 (1) ◽  
pp. 92-97 ◽  
Author(s):  
J.C. Scaiano ◽  
Terrence J. Connolly ◽  
Nadereh Mohtat ◽  
Claudette N. Pliva
Keyword(s):  
Free Radical ◽  
Exploratory Study ◽  
State Energy ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Time Resolved ◽  
Excited Triplet ◽  
Excited State Energy ◽  
Pyrene Fluorescence

Several compounds of the type PhCR1R2-TEMPO (where TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxide) have been prepared and examined as potential photosensitized initiators for "living" free radical polymerizations. For example, these compounds are excellent quenchers of triplet xanthone (rate constants in the range (8.0–13) × 108 M−1 s−1) and result in the formation of benzylic and TEMPO radicals. The importance of excited state energy and nature of the excited triplet state have also been explored. We also tested pyrene as a possible singlet sensitizer. While pyrene fluorescence is efficiently quenched, the process does not lead to cleavage of the C—O bond. A model is proposed to account for this anomaly in the photosensitized decomposition of these TEMPO adducts. Keywords: TEMPO, laser flash photolysis, time resolved emission spectroscopy, sensitizers, quenching, photoinitiator.

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