Wavelength and Functional Groups in Spectroscopy

Wavelength and Functional Groups in Spectroscopy

  • Wavelength Interpretation (in cm^-1)

    • Each range corresponds to specific functional groups based on their absorption characteristics.

  • Wavelength Ranges

    • 3500 - 3000 cm^-1

    • Functional Group: -OH or -C-H

    • Notes: This absorption is broad and strong; it is always present for alcohols or phenols.

    • 3000 - 2800 cm^-1

    • Functional Group: -C-H

    • Notes: Medium intensity with sharp peaks, often associated with aliphatic hydrocarbons.

    • 2500 - 2000 cm^-1

    • Functional Group: -H

    • Notes: This range can indicate specific bond types; the intensity may vary.

    • 2000 - 1800 cm^-1

    • Functional Groups:

      • -NH
      • -C=C- (Alkyne) or -C=N (Nitrile)

    • Notes: In this region, sharp peaks can indicate the presence of double or triple bonds related to nitrogen or carbon.

  • Notes Recap

    • Broad and Strong Absorption:
    • Characteristic of functional groups such as hydroxyl (-OH)
    • Medium and Sharp Peaks:
    • Indicate aliphatic or aromatic structures associated with carbon-hydrogen bonds.

  • Strength of Absorption Peaks:

    • Strong: Indicates a strong vibrational mode or bond strength in molecular structure.
    • Weak: Suggests less interaction or presence of less polar groups.