Chlorine fluorescence lifetime

Similarly, chlorination, bromination and iodination are achieved by high temperature and high pressure reactions with SOCl2, Br2 and I2 respectively. The type of halogen does not seem to significantly affect the fluorescence emission, but rather influences the fluorescence lifetimes [26]. 

A series of chlorophyll-like donor (a chlorin) linked having C60 (chlorin-C60) or porphyrin-C60 dyads with the same short spacer have been synthesized as shown in Schemes 13.1 and 13.2 [39, 40]. The photoinduced electron-transfer dynamics have been reported [39, 40]. A deoxygenated PhCN solution containing ZnCh-C60 gives rise upon a 388-nm laser pulse to a transient absorption maximum at 460 nm due to the singlet excited state of ZnCh [39]. The decay rate constant was determined as 1.0 X 10u s-1, which agrees with the value determined from fluorescence lifetime measurements [39]. This indicates that electron transfer from 1ZnCh to C60 occurs rapidly to form the CS state, ZnCh +-C60 . The CS state has absorption maxima at 790 and 1000 nm due ZnCh+ and C60, ... 

Emission electronic spectra of dioxins are characterized by phosphorescence and very low intensity fluorescence. The phosphorescence lifetime was found to change slowly as the number of the chlorine atoms varies in a dioxin molecule <2000JST(553)243>. 

A fiber-optic oxygen sensor with the fluorescence decay time (rather than its intensity) as the information carrier has been described by two groups [119, 120]. In the former work, a ruthenium complex is immobilized in silicone-rubber, and quenching by oxygen is measured by either lifetime or intensity measurements. The 337-nm line of a nitrogen laser served as the excitation line, and the dye was dissolved in a silicone-rubber membrane placed in the fluorimeter. This sensing membrane is reported to be highly specific, and chlorine and sulfur dioxide were the only interferents. 

E. PHOSPHORESCENCE SPECTRA In addition to fluorescence emission bands, some of these compounds may show phosphorescence emission bands which are on the long wave length side of the fluorescence spectra. Calvin and Dorough (16a) have shown that zinc chlorin, and a mixture of chlorophylls a plus b, possess phosphorescence bands beginning in the range of 7800 to 8000 A and extending into the infrared. The lifetime of the phosphorescent state was about 0.2 second. Copper chlorin, which does not show fluorescence, also does not show phosphorescence. 

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