Raman spectroscopy sample holders

Sample Preparation and Handling. - There are a wide variety of sampling techniques used for collecting Raman spectra of solid catalyst systems depending on the type of sample and the conditions under which the measurement is to be made. Simple sample holders can be used if the sample is stable under ambient and atmospheric conditions. The sample morphology is not as important in Raman spectroscopy as it is in other types... 

The molecular structures of the surface vanadium oxide species on the different supports were examined with Raman spectroscopy. The Raman spectrometer system possessed a Spectra-Physics Ar+ laser (model 2020-05) tuned to the exciting line at 514.5 nm. The radiation intensity at the samples was varied from 10 to 70 mW. The scattered radiation was passed through a Spex Triplemate spectrometer (Model 1877) coupled to a Princeton Applied Research OMA III optical multichannel analyzer (Model 1463) with an intensified photo diode array cooled to 233 K. Slit widths ranged from 60 to 550 m. The overall resolution was better than 2 cm l. For the in situ Raman spectra of dehydrated samples, a pressed wafer was placed into a stationary sample holder that was installed in an in situ cell. Spectra were recorded in flowing oxygen at room temperature after the samples were dehydrated in flowing oxygen at 573 K. 

Small amounts of samples can be analyzed by Raman spectroscopy and a variety of sample holders are available, ranging from stainless steel holders to glass NMR tubes. The samples are analyzed neat, eliminating the need for sample preparation procedures that may induce solid form changes. Since a laser is used, only a small portion of the sample is in the beam during analysis. 

As in almost all spectroscopic methods, the instrumentation for infrared or Raman spectroscopy consists of a radiation source, a monochromator or wavelength-selection device of some type, a sample holder, and a detector. 

Chemical imaging is described, including confocal Raman imaging. UV and visible spectroscopy includes innovations such as flow-through sample holders and fiber-optic probes, as well as instruments for analysis of submicroliter volumes and nondestructive analysis for nucleic acid and protein determinations. UV absorption spectral interpretation for organic molecules is covered in depth. Applications described include nucleic acid and protein measurements, spectrophotometric titrations, and new applications in forensic chemistry. Nephelometry, turbidimetry, fluorescence, and phosphorescence are described in detail, including instrumentation and applications. The measurement of color using the CIE system is described with examples. 

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