Raman luminescence

Spectroscopic analyses of solid-state reactions must first use solid-state techniques (IR, UV/Vis, Raman, luminescence, NMR, ESR, CD, X-ray powder diffraction, DSC, etc.) in order to secure the solid-state conversion, before the solution techniques (detection of minor side products, specific rotation, etc.) are applied. 

The transducers most commonly employed in biosensors are (a) Electrochemical amperometric, potentiometric and impedimetric (b) Optical vibrational (IR, Raman), luminescence (fluorescence, chemiluminescence) (c) Integrated optics (surface plasmon resonance (SPR), interferometery) and (d) Mechanical surface acoustic wave (SAW) and quartz crystal microbalance (QCM) [4,12]. 

INDIRECT STRUCTURAL METHODS Optical spectroscopy (IR, visible, UV, Raman, luminescence, LIBD)... 

A variety of spectroscopic techniques including Raman, luminescence, NMR, EPR, mass spectrometry, and circular dichroism, have been used to monitor the nature and redox behavior of electrogenerated or adsorbed spedes. The simphdty and richness of the structural information obtained from infrared spectroelectrochemistry have contributed to its widespread use. Because the pz bridged dimers have relatively stable 1 mixed valence states and contain a good spectroscopic chromophore, i.e., CO, the nature and rate of charge transfer have been investigated further by infrared spectroelectrochemistry. 

The spectra of studied diamonds may be sub-divided on two main groups according to the Raman/Luminescence intensities ratio. Figure 6.33 presents the first group where this ratio changes from 3.6 to 1.7 and down to 1. It was found that... 

Diamonds belonging for the second grope has low and very similar Raman/ Luminescence ratios, namely between 0.13 and 0.2. To differentiate between those diamonds several additional spectral features may be used. N3 is the only luminescence center with an appreciable fine structure at 300 K, while its zero-phonon line at 415 nm is characterized by different intensities down to practically total disappearance. For example, the ratio between the maximum intensity of N3 band at 440 nm and the 415 nm line intensity is changed in studied samples between 1.7 and 1.2. Figure 6.34 demonstrates the comparison between two samples with similar Raman/Luminescence ratio and even similar absolute intensity, while the ratio of... 

Fig. 6.34 (a-c) Differentiation between diamonds with similar Raman/Luminescence ratios different I440/I415 ratios in (a) and different ratios between the second and the third components in kinetic series (A = 10 ns)... 

For the following Raman-luminescence individualization , where the gating time was very narrow (Fig. 6.35a) we used delayed time resolved spectroscopy with excitation by 355 nm and delay time of several ps (Fig. 6.35b), which is usually quite enough. In certain cases the fast (Fig. 6.35c) and slow (Fig. 6.35d) components of the luminescence with excitation by 248 nm give additional identification features. 

Electrochemical techniques have been developed into very powerful tools for research and technology. However, decades ago, researchers started to understand that even more insight could be obtained if electrochemical techniques were combined with additional spectroscopic tools. Among these it is sufficient to mention infrared spectroscopy, Raman spectroscopy, luminescence techniques, electroreflection or ellipsometry. 

The most commonly used methods for characterization of ruthenium sensitizers are elemental analysis, NMR, IR, Raman, UV-vis, and luminescence spectroscopy and cyclic voltammetry, HPLC, and X-ray crystallography. 

Vo-Dinh T., Miller G.H., Bello J., Johnson R., Moody R.L., Alak A., Fletcher W. R., Surface-active substrates for Raman and luminescence analysis, Talanta 1989 36 227-234. 

The most often used detection method for the optical sensors are based on absorption, luminescence, reflectance, and Raman scattering measurements. The basic theory and instrumentation of most of these... 

---