Fluorescence halogen atoms

Chemiluminescence and photoluminescence in diatomic iron oxide, Rb2, and alkali-metal dimers with halogen atoms and metal vapour-oxidant flames,202 203 lifetime measurements of selectively excited states of diatomic hydrides,204 photodissociation of alkali-metal halide vapours,206 spin-orbit relaxation of the HTe ( 2IIi) radical,20 the photodecomposition of metal carbonyl anions such as [Mn(C04)] in the vapour phase,207 and the fluorescence of Rhodamine 6G in the vapour phase 208 have been studied in recent reports. In the last study it was concluded that an insufficient concentration of the fluorescing dye could be maintained in the vapour phase to permit laser action to occur. 

All major ash elements and some trace elements are determined in coal or fly ash by inductively coupled plasma emission spectrometry. Parr oxygen bomb combustion followed by ion selective electrode. X-ray fluorescence or atomic absorption spectrom-etric measurements are used to determine halogens, sulfur, nitrogen, mercury, arsenic, selenium, and phosphorus. Hydride generation-atomic absorption spectrometry is used to determine traces of As,... 

The high sensitivity of atomic resonance fluorescence spectrometry has been exploited in a study of the rates of a series of halogen atom ( Ps/a) plus halogen molecule reactions, most of which are extremely rapid at 298 K ... 

A very widely employed method for the measurement of spin-orbit state-specific rate constants is the time-resolved measurement of the concentrations of individual atomic levels after formation of these species from a suitable precursor, either by flash photolysis [13], or, more recently, by laser photodissociation. The concentrations of the various atomic reactant states are monitored by atomic absorption or fluorescence spectroscopy using atomic emission sources [14], or, for spin-orbit-excited states, by observation of the spontaneous infrared emission [15-18]. Recently, Leone and co-workers have utilized gain/absoiption of a colour centre and diode infrared laser to probe the relative populations of ground and spin-orbit excited halogen atoms produced in a chemical reaction [19] and also by photodissociation [20],... 

Substituents have considerable influence on emission characteristics of aromatic compounds. Heavy atom substituents tend to reduce the fluorescence quantum yield 4>f in favour of phosphorescence emission f. In halogen series the effect increases in the order F < Cl < Br < I. In Table 5.1 are recorded experimental data for halogen substituted Naphthalenes. 

Donohoue et al. [31] has reported two other kinetic data sets for Cl and Br reactions using a pulsed laser photolysis-pulsed laser induced fluorescence spectroscopy. These data sets are obtained using pseudo-first order conditions with respect to halogens or mercury and experiments were performed at a broad range of temperatures. The authors of these studies indicate an uncertainty estimation of 50% in the rate coefficients due to the determination of absolute concentrations of chlorine and bromine atoms [31]. Sumner et al. [20] reinvestigated both reactions using a 17.3 m environmental chambers equipped with fluorescent lamps and sun lamps to mimic environmental reactions, and evaluated the rate constants... 

The method consists in allowing alkali metal vapor (A2 + M) to diffuse (with carrier gas, usually) through a nozzle into a halogen or halide. The magnitude of the reaction zone may be observed, since the residual alkali metal atoms will fluoresce strongly when illuminated with resonance radiation, and from that the rate of reaction may be estimated. 

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