23 Terms
Contributors in Spectroscopy
Spectroscopy
attenuated total reflectance (ATR)
Chemistry; Spectroscopy
A reflectance sampling technique. In ATR, infrared radiation impinges on a prism of infrared transparent material of high refractive index. The total internal reflectance based design assures that ...
angular divergence
Chemistry; Spectroscopy
The spreading out of an infrared beam as it travels through the FT-IR. Angular divergence contributes to noise in high resolution spectra, and can be a limit to achievable resolution.
absorbance
Chemistry; Spectroscopy
Units used to measure the amount of IR radiation absorbed by a sample. Absorbance is commonly used as the Y axis units in IR spectra. Absorbance is defined by Beer’s Law, and is linearly proportional ...
zero optical path difference
Chemistry; Spectroscopy
The mirror displacement at which the optical path difference for the two beams in an interferometer is zero. At ZPD, ZOPD, the detector signal is often very large, the centerburst.
j stop
Chemistry; Spectroscopy
An aperture placed in the beam to restrict the divergence to the maximum compatible with the selected resolution. When choosing lower resolution you can improve the S/N by opening the stop. Note that ...
zero path difference
Chemistry; Spectroscopy
The mirror displacement at which the optical path difference for the two beams in an interferometer is zero. At ZPD, ZOPD, the detector signal is often very large, the centerburst.
wavenumber
Chemistry; Spectroscopy
1/wavelength, the units of wavenumbers are cm-1, and are most commonly used as the X axis unit in infrared spectra. 1 µm = 1,000 nm = 10,000 cm-1 5 µm = 5,000 nm = 2,000 cm-1
