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An "interferogram" from a Fourier-transform spectrometer. This is the "raw data" which can be Fourier-transformed into an actual spectrum. The peak at the center is the ZPD position ("zero path difference"): Here, all the light passes through the interferometer because its two arms have equal length.
The spectra are plotted in units of log inverse reflectance (log 1/R) versus wavenumber. Alternative plots of Kubelka-Munk units can be used, which relate reflectance to concentration using a scaling factor. A reflectance standard is needed in order to quantify the reflectance of the sample because it cannot be determined directly. [2] [3]
Fourier transform infrared spectroscopy (FTIR) [1] is a technique used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gas. An FTIR spectrometer simultaneously collects high-resolution spectral data over a wide spectral range.
There are two main approaches to two-dimensional spectroscopy, the Fourier-transform method, in which the data is collected in the time-domain and then Fourier-transformed to obtain a frequency-frequency 2D correlation spectrum, and the frequency domain approach in which all the data is collected directly in the frequency domain.
The schematic representation of a nano-FTIR system with a broadband infrared source. Nano-FTIR (nanoscale Fourier transform infrared spectroscopy) is a scanning probe technique that utilizes as a combination of two techniques: Fourier transform infrared spectroscopy (FTIR) and scattering-type scanning near-field optical microscopy (s-SNOM).
FTIR mode Sample preparation Schematic diagram Transmission FTIR: Transmission mode is the most widely used FTIR technique in geoscience due to its high analysis speed and cost-efficient characteristics. [4] The sample, either a rock or a mineral, is cut into a block and polished on both sides until a thin (typically 300 to 15 μm) wafer is ...
The term apodization is used frequently in publications on Fourier-transform infrared (FTIR) signal processing. An example of apodization is the use of the Hann window in the fast Fourier transform analyzer to smooth the discontinuities at the beginning and end of the sampled time record.
Software for mass spectrometry imaging developed by the Swiss Institute of Bioinformatics. [67] MSiReader Freeware: Vendor-neutral interface built on the Matlab platform designed to view and perform data analysis of mass spectrometry imaging (MSI) data. [68] Matlab is not required to use MSiReader. MS Interpreter Freeware