摘要:

Laser induced infrared fluorescence1,2is a potential method for the remote detection of atmospheric pollutants.3,4In evaluating this technique as a quantitative analytical tool, two important parameters are (a) the lifetimes of the excited species and (b) the quenching efficiencies of various molecules which would be expected to be in the atmosphere and which may collide with the excited species. Such quenching would lead to low fluorescence intensity and low analytical data. We have measured the quenching of the fluorescence of ethylene, which is a common hydrocarbon pollutant, by nitrogen, nitrogen saturated with water vapor, and air.

ISSN:0038-7010    

DOI:10.1080/00387017308065475

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The Carbon Rod Atomizer (CRA) was evaluated for routine trace analysis of vanadium in crude oil by atomic absorption spectroscopy with a carbon (graphite) tube as a micro-furnace. Two crude oil samples were analyzed, both by standard addition and standard working curve methods, and the results confirmed by analysis with flame atomic absorption spectroscopy using a fuel-rich nitrous oxide-acetylene flame. Because of the relative involatility of vanadium at the temperature of the CRA, quantitative recoveries of vanadium in crude oil occur only when the vanadium content of the sample injected into the CRA does not exceed the limit of about 1 × 10−8g. A sensitivity (weight/1% absorption) of 7.0 × 10−11g and detection limit (signal-to-root-mean-square-noise equal to two) of 6.9 × 10−12are reported.

ISSN:0038-7010    

DOI:10.1080/00387017308065476

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The kinetics of triplet-triplet energy transfer in the gas phase has been studied for various donor-acceptor pairs of aromatic hydrocarbons and ketones. For all the donor-acceptor pairs investigated the triplet-triplet energy transfer efficiencies are much lower than unity. The triplet triplet energy transfer was used to gain insight into the paths of intramolecular excitation energy degradation in benzophenone and anthraquinone vapours and to obtain sensitized anti-Stokes annihilation delayed fluorescence of vapours of anthracene and its derivatives.

ISSN:0038-7010    

DOI:10.1080/00387017308065477

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Hydrogen bonding in five benzhydrols and triphenyl methanol have been studied in the solid phase and on dissolution. Attempts have been made to characterize possible molecular species in the solid structure.

ISSN:0038-7010    

DOI:10.1080/00387017308065478

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

In our search for new lanthanide shift reagents, we have recently reported1the use of tris(acetylacetonato)ytterbium(III), Yb(acac)3, in producing downfield shifts of PMR signals of benzyl alcohol. During this study, it was noted that the corresponding Pr(acac)3failed to produce the expected shifts analogous to those by other Pr(III)-complexes2. In examining a series of acetylacetonate complexes of the lanthanides and an analysis of the data already available in the literature, it was concluded1that the ability of a lanthanide complex to act as a shift reagent is strongly dependent on the nature of the ligand in its coordination shell. Hence, we have started exploring complexes of lanthanide ions with different donor atoms that would act as shift reagents.

ISSN:0038-7010    

DOI:10.1080/00387017308065479

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The reaction of nitrogen dioxide with carbonyl compounds having a methylene or vinyl group adjacent to the corbonyl leads to the formation of stable iminoxy radicals1-3. Evidence1,2,4has been presented that the precursor of these iminoxy radicals is probably the corresponding oxime formed by rearrangements of the intermediate nitroso compounds. There have also been reports on the e.s.r. detection of some cis-trans isomers of some iminoxy radicals in methanol or in neat liquid1,5. We wish to report here a drastic solvent effect on the conformations of some iminoxy radicals formed by the reaction of NO2with trifluoroacetylacetone.

ISSN:0038-7010    

DOI:10.1080/00387017308065480

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The fluorescence efficiency of the rare-earth ions in organic solvents depends strongly upon the solvent molecules in the primary solvation sphere and to a lesser extent upon the molecules located in the secondary solvation sphere of the ion(1-4). The fluorescence efficiency of the rare-earth ions in many organic solvents is relatively low probably due to an efficient electronic excitation energy transfer from the lowest excited state of the rare-earth ion to the organic solvent, via some high overtones of certain vibrational modes associated with the solvent under consideration. Contrary to this behavior, solutions of the rare-earth ions in solvents associated with very low-energy vibrational modes, “aprotic” solvents, like POCl3:SnCl4, POCl3:ZrCl4, POCl3:SbCl5etc., exhibit a remarkable enhancement in both the fluorescence efficiencies and lifetimes of the rare-earth ions(5). Neither the organic nor the “aprotic” solvents used absorb light in the excitation region i.e., 370 mμ to 410 mμ. Since the absorption spectra of these solvents appear at wavelengths shorter than 300 mμ one may rule out both energy transfer from the solvent to the rare-earth ion and decreased light absorption by the ion due to the presence of the solvent. The “aprotic” solvents do not have groups containing H-atoms,which are associated with high energy vibrational modes. The importance of such “aprotic” solvents is not associated only with a mere fluorescence enhancement. Both the fluorescence efficiencies and lifetimes depend upon the composition of these solvents(5).

ISSN:0038-7010    

DOI:10.1080/00387017308065481

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

ISSN:0038-7010    

DOI:10.1080/00387017308065482

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0038-7010    

DOI:10.1080/00387017308065474

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor