A high performance multiwavelength flash photolysis apparatus

1980 ◽  
Vol 6 (S1) ◽  
pp. 131-131 ◽  
Author(s):  
Rainer Uhl ◽  
Birgit Meyer
Keyword(s):  
High Performance ◽  
Flash Photolysis ◽  
Photolysis Apparatus

Quantum Yields for the Photodegradation of Pollutants in Dilute Aqueous Solution: Phenol, 4-Chlorophenol and N-Nitrosodimethylamine

1996 ◽  
Vol 1 (2) ◽  
Author(s):  
Te-Fu L. Ho ◽  
James R. Bolton ◽  
Ewa Lipczynska-Kochany
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Quantum Yield ◽  
High Performance ◽  
Flash Photolysis ◽  
Quantum Yields ◽  
Visible Absorption ◽  
Dilute Aqueous Solution ◽  
Uv Visible ◽  
Photolysis Of Phenol

AbstractA broadband method has been applied to determine the quantum yields for the photochemical removal of three common pollutants: phenol, 4-chlorophenol and N-nitrosodimethylamine (NDMA) in dilute aqueous solution. Flash photolysis (xenon flash lamps) was used to cause a significant amount of photolysis without photolyzing intermediates. The analysis of reactant depletion following a single flash was carried out by high- performance liquid chromatography (HPLC) or UV/visible absorption spectroscopy. The method for determining quantum-yields employed p-benzoquinone as an actinometer and was validated by determining the average (200-400 nm) quantum yield for the generation of hydroxyl radicals from the photolysis of hydrogen peroxide (0.90 ± 0.10) and the quantum yields for the photolysis of phenol (0.13 ± 0.02) and 4-chlorophenol (0.24 ± 0.04). The values determined agree very well with the literature ones obtained with monochromatic radiation. The quantum yield for the direct photolysis of NDMA was found to be 0.11 ± 0.03 at neutral pH and 0.27 ± 0.02 at pH 2-4. Under conditions where hydrogen peroxide is the principal absorber, the NDMA quantum yield is 0.32 ± 0.04, independent of pH in the range 2-8.

scholarly journals NEW HIGH PERFORMANCE CAGED NO : LASER FLASH PHOTOLYSIS AND BIOLOGICAL APPLICATIONS

1997 ◽  
Vol 75 ◽  
pp. 19
Author(s):  
Ken Fujimori ◽  
Shigeyuki Namiki ◽  
Tatsuo Arai ◽  
Sachie Asada ◽  
Hiroshi Hama ◽  
...  
Keyword(s):  
High Performance ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Biological Applications

Design of a flash photolysis apparatus

1971 ◽  
Vol 4 (6) ◽  
pp. 417-420 ◽  
Author(s):  
M Vallotton ◽  
U P Wild
Keyword(s):  
Flash Photolysis ◽  
Photolysis Apparatus

A versatile flash photolysis apparatus

1992 ◽  
Vol 63 (3) ◽  
pp. 2069-2072 ◽  
Author(s):  
Charles J. Beischel ◽  
Stacie K. Moore ◽  
Rosalie K. Crouch ◽  
Daniel R. Knapp
Keyword(s):  
Flash Photolysis ◽  
Photolysis Apparatus

Photosensitization by chiral drugs: Looking for stereodifferentiating photoprocesses in the presence of biomolecules

2005 ◽  
Vol 77 (6) ◽  
pp. 995-1000
Author(s):  
Virginie Lhiaubet-Vallet
Keyword(s):  
High Performance ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Single Strand ◽  
Type I ◽  
Chiral Drugs ◽  
Time Resolved ◽  
Strand Breaks ◽  
Single Strand Breaks

Photoreactivity of chiral carprofen (CP) and ofloxacin in the presence of two biomolecules, namely, DNA and human serum albumin (HSA), has been reported. Analysis of the photosensitization of 2'-deoxyguanosine and thymidine (Thd) by high-performance liquid chromatograpy has shown that racemic ofloxacin and levofloxacin [its (S)-stereoisomer] acts by a mixed type I/type II mechanism, while CP does not lead to significant degradation of the nucleosides. Studies on DNA relaxation have revealed formation of single-strand breaks and specific alterations of DNA bases. Ofloxacin and levofloxacin photoinduce direct single-strand breaks and formation of purine and pyrimidine oxidative photoproducts; no Thd dimer has been detected. CP produces only photosensitized single-strand breaks. Moreover, DNA photosensitization has shown a weak enantiodifferentiation in favor of levofloxacin and (S)-CP. In the case of HSA, a remarkable stereodifferentiation has been found in the interaction between the excited triplet state of CP and protein. Time-resolved laser flash photolysis measurements revealed the presence of two components with different lifetimes that have been assigned to complexation of CP to the two binding sites of albumin. Moreover, photobinding of the drug to protein and formation of the dehalogenated photoproduct of CP proceed via stereodifferentiating photoprocesses.

THE ABSORPTION SPECTRUM OF THE Si2 MOLECULE

1963 ◽  
Vol 41 (1) ◽  
pp. 152-160 ◽  
Author(s):  
R. D. Verma ◽  
P. A. Warsop
Keyword(s):  
Absorption Spectrum ◽  
Dissociation Energy ◽  
Ground State ◽  
Flash Photolysis ◽  
Lower State ◽  
The Third ◽  
Photolysis Apparatus ◽  
Vibrational Constants

Three band systems of Si2 have been found in absorption with a flash photolysis apparatus. Two of the band systems at 3200 and 2100 Å are new, whereas the third is an extension of the 3Σ–3Σ system observed by Douglas in emission. All three systems have the same lower state and arise from [Formula: see text] transitions. It is very probable that the [Formula: see text] state is the ground state of the Si0 molecule. Rotational and vibrational constants of all four 3Σ states have been determined. The dissociation energy of Si2 is estimated to be 3.0 ± 0.2 ev.

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