Explain the factors that affect the intensities of absorption in IR spectroscopy.
#Please anyone to help me with explanation i have to attend test by tomorrow help me out.
Try reading articles on it:
https://en.wikipedia.org/wiki/Absorption_spectroscopy
The major factor that affects intensity of absorption is the frequency.
Atoms only absorb certain discrete energies of incident waves, based on the energy levels of their electrons.
Since frequency and energy of the incident waves are proportional, this means that only certain frequencies are readily absorbed.
Thus, certain specific frequencies have high amounts of absorption while the rest remain unaffected.
For a given absorption energy, the depth of the measurement, and the width of the absorption band, is largely a measurement error issue with the instrument being used. For a specific medium of set density, the amount of absorption is directly related to thickness. Double the thickness, and the incident energy has to encounter twice the amount of molecules to pass thru.
In infrared (IR) spectroscopy, the intensities of absorption bands can be influenced by several factors. Here are the key factors that affect the intensities of absorption in IR spectroscopy:
1. Molecular Structure: The structure of the molecule being analyzed plays a significant role. Different types of chemical bonds, such as C-H, O-H, N-H, and C=O, have characteristic vibrational frequencies. The intensity of absorption depends on the strength of these bonds and the number of bonds in the molecule.
2. Dipole Moment: A molecule's dipole moment is another crucial factor. The greater the difference in electronegativity between the atoms forming a bond, the stronger the dipole moment. Stronger dipole moments result in more intense absorption bands.
3. Molecular Symmetry: Symmetric molecules tend to have weaker absorption bands compared to asymmetric ones. In symmetric molecules, vibrations result in no net dipole change and, thus, weaker IR absorption.
4. Bond Strength: The strength of the bond being analyzed affects the intensity of the absorption. Weaker bonds vibrate more easily, resulting in stronger absorption bands.
5. Molecular Size: The size of the molecule can also influence the intensity of absorption. As the size of the molecule increases, the number of possible vibrational modes also increases, leading to more absorption bands.
6. Overlapping Bands: Sometimes, absorption bands can overlap, making it difficult to identify individual peaks. Overlapping bands can affect the apparent intensity and shape of absorption bands.
To understand these factors, it is essential to study the functional groups present in a molecule, their characteristic vibrational frequencies, and the factors that affect bond strength and molecular symmetry. Additionally, analyzing spectral data and comparing spectra can yield significant insights into the intensities of absorption bands in IR spectroscopy.