IR‐Spektroskopie

Wood production, wood technology, and biotechnological impacts

“…1). Stretching vibrations are changes in the molecular bond length between two atoms and deformations are changes of the bond angle (Günzler & Gremlich 2002). Generally in IR absorption spectra, the total number of observed absorption bands is different from the total number of fundamental vibrations because some modes of motion may be IR inactive and a single vibrational frequency may cause more than one mode of motion.…”

“…-273.15ºC, continuous vibrations exist in all atoms in a molecule with respect to each other (Sherman Hsu 2000, Günzler & Gremlich 2002. When the frequency of a specific vibration is equal to the frequency of the infrared (IR) radiation, molecules absorb the radiation.…”

“…By absorption of IR radiation, a molecule can proceed from one energy level E initial to a higher energy level Efinal. The difference in the energy levels (Efinal-Einitial = hν) results in bending, stretching, and twisting of the chemical bonds, leading to characteristic transmittance and reflectance patterns (Chalmers & Griffiths 2002, Günzler & Gremlich 2002.…”

“…Specific parts of the IR spectrum are absorbed by the sample according to its chemical composition (Günzler & Gremlich 2002). The stretch and deformation vibrations of specific molecular bonds in the sample, for example C-H, O-H, N-H, C=O, etc., result in absorption bands at specific wavenumbers of the FTIR spectrum.…”

“…3. Earlier, measurement of FTIR spectra required the preparation of KBr pellets by mixing KBr powder with sample powder and pressing these into transparent discs that subsequently were IR radiated (Günzler & Gremlich 2002). An easier and faster method to measure FTIR spectra of powdered wood samples or of plane surfaces of wood samples is to combine the FTIR spectrometer with an attenuated total reflection unit (ATR; Fig.…”