Immersion probe, Raman spectroscopy

In recent years, spectroscopic techniques have become invaluable tools for probing the molecular structures and interactions in CEPs. Three of the most useful are the UV-visible, circular dichroism, and Raman spectroscopy techniques. In each of these cases, absorption of the incident radiation by water (and many other electrolytes) is minimal, meaning that it is possible to obtain the spectra by reflection or transmission of light from the sample while it is immersed in an electrolyte as part of an electrochemical cell. Another valuable technique has been electron spin resonance (ESR) spectroscopy, which involves the absorption of microwaves. 

Raman spectroscopy has been shown to be useful in the study of the kinetics associated with the solution-mediated aqueous transformation of anhydrous carbamazepine to its dihydrate phase. Using a Raman immersion probe to establish the phase composition, the thermodynamics associated with the system were studied in ethanol-water mixtures through measurements of the solubility of both forms over the temperature range of 0-60 Raman spectroscopy was also... 

Nowadays, the availabihty of fiber-optic probes offers several possibilities for performing in situ catalyst characterization. As quartz glass is transparent to Raman laser and UV-vis radiation, these spectroscopies are particularly versatile. Thus, the respective UV-vis probe or Raman laser optics can be focused from outside or directly immersed in the reaction solution (in the latter case, a Raman probe is used). In contrast, infrared radiation is strongly adsorbed by quartz hence, special infrared transmissive fibers are required. Such silver halogenide fibers have proven suitable and are now well established [35-37] despite their fiagihty and degradation over time. 

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