TechNote | How to choose the right resolution for your sample type
Choosing the right spectral resolution is essential for obtaining good FTIR spectra. A resolution that is too low may fail to resolve bands of close proximity while a resolution that is too high introduces noise and increases the measurement time. This report explains how to balance resolution, sensitivity, and measurement time based on sample type.
Understanding spectral resolution
To understand how to choose the right resolution, it is first important to define what spectral resolution actually means and how it affects the quality of an FTIR spectrum.
What is spectral resolution?
The resolution of an FTIR spectrometer is a measure of how well an instrument distinguishes peaks that are close together. For example, if two peaks appear at 2999 cm-1 and 3000 cm-1 and are clearly separated in the spectrum, the measurement was likely made at a resolution of 1 cm-1 or higher. This is considered a high resolution. In contrast, a resolution of 16 cm-1 would only allow peaks that are at least 16 cm-1 apart to be resolved, meaning the two example peaks would appear as a single merged peak (see Figure 1).
High-resolution spectra often display more distinct peaks than low-resolution ones. Since each peak represents specific molecular vibrations, a spectrum with more peaks contains more information. Thus, in general, the higher the resolution, the higher the information content that can be extracted from the sample.
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