Solution luminescence spectroscopy

The emissive behaviors of 2, 3, and 22-25 at 77 K in glassy solutions are sensitive to the complex concentration in the range 10-3 to 10-5 mol dm-3. At complex concentration below 10-5 mol dm-3, the emission spectrum is 

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Table 5.12 shows the main features of luminescence spectroscopy. The much higher sensitivity and specificity of luminescence techniques compared to absorption techniques is an obvious advantage for excitation spectra. In solution studies, pg ml. 1 levels can often be determined, as compared to p,gmL-1 levels in absorption spectroscopy. The greater sensitivity of luminescence techniques stems from the fact that the... 

Sinkov, S.I. Choppin, G.R. Taylor, R.J. Spectrophotometry and luminescence spectroscopy of acetohydroxamate complexes of trivalent lanthanide and actinide ions, J. Solut. Chem., 36 (2007) 815-830. 

Interaction of the nitrate ion with lanthanide(III) in acetonitrile solution was studied by conductivity, vibrational spectroscopy and luminescence spectroscopy. Bidentate nitrate with approximate C2V local symmetry was detected. FT-IR spectral evidence for the formation of [La(N03)5]2, where La = Nd, Eu, Tb and Er with coordination number 9.9 has been obtained [128]. Two inequivalent nitrate ions bound to lanthanides were detected by vibrational spectroscopy. The inequivalent nature varied with different lanthanides. For example three equivalent nitrate groups for La and Yb, one nitrate different from the other two for Eu ion were detected. Vibrational spectral data point towards strong La-NC>3 interaction in acetonitrile [129]. Stability constants for lanthanide nitrate complexes are given in Table 4.10. 

In CH2CI2 solution, 1,10-phenanthroline and its derivatives can be protonated on the nitrogen atoms, and the reaction can be followed by absorption and luminescence spectroscopy [61]. 

A limitation of the application of luminescence spectroscopy to the analysis of real samples is its lack of specificity owing to similarities in spectral bandshapes and spectral positions of the luminescence spectra of many compounds. An obvious solution to this problem is the separation of the analytical sample s interfering constituents from each other before quantitation by fluorescence. High-performance liquid chromatography (HPLC) and related separation methods can be coupled to fluorescence spectroscopy to take advantage of the sensitivity of the spectroscopic method and the specificity of the separation method. 

Nickel, in a very useful paper, has discussed the elimination of polarization bias effects from the measurement of luminescence properties and transient absorption in isotropic solutions. The theoretical treatment is fully developed and recommendations are given for making reliable observations under a variety of experimental conditions are detailed. Determination of quantitative data from steady state luminescence spectroscopy is by no means as straightforward as many workers assume this work very convincingly demonstrates otherwise. 

Lochhead MJ, Wamsley PR, Bray KL. Luminescence spectroscopy of europium(III) nitrate, chloride, and perchlorate in mixed ethanol- water solutions. Inorg Chem 1994 33 2000-3. 

The problem seems to call for a new approach to the measurement of the small currents. We have carried out research on a scheme designed to take advantage of well-developed methods for the precise measurement of fast transients in luminescence spectroscopy. By transducing the electrochemical cell current to a photon flux, instead of a voltage, one transforms an electrochemical measurement with a difficult electronic solution into an optoelectronic problem with several known solutions. 

From analysis of lanthanide (Ln " ") tetraazatetrakis-phosphinato and phosphonato complexes (42)," self-association was observed in aqueous solution for both the [Ln(DOTP -OEt)] and [Ln(DOTP -OBu)] ester complexes through examination of their P-NMR-, EPR-, and luminescence-spectroscopy, as well as vapour-pressure osmometry data. The X-band EPR spectra were recorded for [Gd(DOTP -H)] , [Gd(DOTP -Et)] , [Gd (DOTP -OEt)], and [Gd(DOTP -OBu)] complexes in the 1-10 mmol/L concentration range at pH 7.0 and 298 K, which gave approximate Lorentzian lines with a g value around 2.0 and variable peak-to-peak line widths, (d/fpp), dependent on the concentration of the complexes. An increase in the line width was observed in all cases but was much larger for [Gd(DOTP -OEt)] increasing from 40.5 to 80.0 mT. In the phosphinato complex [Gd(DOTP -H)] , no increase was observed with A//pp around 26 mT, indicating that the... 

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