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Infrared Spectroscopy definitions

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  • Infrared Spectroscopy
    Analytical technique using light frequencies to induce molecular vibrations, revealing bond types in a sample.
  • Vibration
    Movement of chemical bonds, such as stretching or bending, caused by absorption of specific light frequencies.
  • Absorption
    Portion of light not transmitted through a sample, appearing as a peak on the IR spectrum and indicating bond presence.
  • Wave Number
    Measurement unit for IR spectra, expressed in reciprocal centimeters, directly related to light frequency.
  • Transmittance
    Percentage of light passing through a sample, with lower values indicating higher absorption at specific frequencies.
  • Fingerprint Region
    Complex IR spectrum area below 1500 cm⁻¹, unique to each molecule, mainly used for molecular identification.
  • Functional Group Region
    IR spectrum area above 1500 cm⁻¹, where characteristic absorptions reveal specific bonds and functional groups.
  • Single Bond
    Bond type with the lowest vibration frequency, typically found in the fingerprint region of the IR spectrum.
  • Double Bond
    Bond type vibrating faster than single bonds, producing absorptions in the 1500–2000 cm⁻¹ region.
  • Triple Bond
    Strong bond vibrating faster than double bonds, with absorptions between 2000–2500 cm⁻¹ in the IR spectrum.
  • Hydrogen Bond
    Single bond to hydrogen, vibrates faster than triple bonds due to hydrogen's low mass, appearing above 3000 cm⁻¹.
  • Peak Strength
    Descriptor of absorption size in IR spectra, indicating how much light is absorbed at a given frequency.
  • Peak Shape
    Descriptor of absorption width in IR spectra, classified as sharp or broad, aiding in bond identification.
  • Asymmetrical Molecule
    Molecule type that produces an IR spectrum due to uneven charge distribution, unlike symmetrical molecules.
  • Reciprocal Centimeter
    Unit for wave number, representing the number of wave cycles per centimeter, used in IR spectral analysis.