how to acquire high quality spectra in IR spectroscopy..?

what are good tips to obtaining a high-quality spectra?

1 Answer

  • 8 years ago
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    Solution spectra are much preferred over solid state (nujol mull, KBr disk) spectra. The less polar the solvent the better (stronger solvent interactions in polar solvents broadens bands: less resolution). So hexanes preferred over CH2Cl2. Opposing this you need a spectrum that gives ~90% transmittance for the strongest band. After you've done a few hundred spectra you can eyeball the amount (2-3 mg in 0.5 mL). We used1 mm spacers and NaCl windows (more robust than KBr) but cutoff is 650 cm^-1

    For solid state grind like crazy (agate mortar and pestle for nujol mull): the more finally divided the particles the better the resolution. Once again 90% transmittance for the strongest peak. I have no experience with the new innovation of reflectance IR but presumably the finer the powder the better.

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