Understanding IR Spectrum: The Role of Transmittance and Absorption

  • Thread starter Samurai33
  • Start date
  • Tags
    Intensity
In summary, intensity on an IR spectrum refers to the height or amplitude of a peak and is used to measure the amount of light absorbed by a molecule at a specific wavelength. It can be affected by factors such as concentration, intermolecular bonds, and molecular structure, and is directly related to the strength of a bond. Intensity is important in the analysis of an IR spectrum as it can help identify functional groups and determine the chemical structure of a molecule.
  • #1
Samurai33
13
0
http://x5.freeshare.us/view/?121fs535045.jpg
In the above diagram, what does the % of transmittance means?
I know the % of transmittance is the reverse of % absorption, but there are more C-H bond per molecule than C=O, why the intensity for C=O is higher(higher absorption)? I really have no clues!
 
Physics news on Phys.org
  • #2
can anyone explain??
 
  • #3


I can provide some insights into the concept of transmittance and absorption in the context of IR spectroscopy. IR spectroscopy is a powerful analytical technique used to identify and characterize chemical compounds based on their unique absorption patterns in the infrared region of the electromagnetic spectrum.

In the diagram provided, the % transmittance refers to the percentage of infrared radiation that passes through the sample without being absorbed. On the other hand, the % absorption refers to the percentage of infrared radiation that is absorbed by the sample. These two values are inversely related, meaning that as one increases, the other decreases.

The intensity of absorption for a particular bond or functional group in a molecule is dependent on several factors, including the type of bond, its strength, and the number of bonds present in the molecule. In the case of C-H bonds, they are typically weaker and less polar than C=O bonds. This means that they absorb less energy and have a lower intensity in the IR spectrum. On the other hand, C=O bonds are stronger and more polar, making them more likely to absorb energy and have a higher intensity in the IR spectrum.

It is also important to note that the intensity of absorption is not solely dependent on the number of bonds present in a molecule. Other factors such as the molecular structure and the orientation of the bonds can also affect the absorption intensity. Therefore, it is not surprising to see that the intensity of C=O absorption is higher than C-H absorption, even though there are more C-H bonds in a molecule.

In summary, the % transmittance and % absorption values in the IR spectrum provide valuable information about the chemical composition and structure of a sample. The intensity of absorption for a particular bond or functional group is influenced by various factors, and it is essential to consider all of these factors when analyzing IR spectra.
 

1. What is intensity on an IR spectrum?

Intensity on an IR spectrum refers to the height or amplitude of a peak on the spectrum. It represents the amount of light absorbed by a molecule at a specific wavelength, and can be used to determine the concentration and structure of the molecule.

2. How is intensity measured on an IR spectrum?

Intensity is measured by the height of the peaks on the IR spectrum. The higher the peak, the greater the intensity of light absorbed by the molecule. Intensity can also be quantified using software programs that analyze and interpret the spectrum.

3. What causes variations in intensity on an IR spectrum?

Intensity variations on an IR spectrum can be caused by a number of factors, including the concentration of the sample, the strength of the intermolecular bonds, and the path length of the light through the sample. Additionally, different functional groups and molecular structures can also affect the intensity of peaks on the spectrum.

4. How is intensity related to the strength of a bond on an IR spectrum?

The intensity of a peak on an IR spectrum is directly related to the strength of the bond between atoms in a molecule. Stronger bonds will absorb more light and have higher intensity peaks, while weaker bonds will have lower intensity peaks. This allows for the identification of different functional groups and bond types in a molecule.

5. How is intensity used in the analysis of an IR spectrum?

Intensity is an important factor in the analysis of an IR spectrum as it can provide valuable information about the composition and structure of a molecule. By comparing the intensity of peaks to known standards or databases, scientists can identify the functional groups and bonds present in a sample and determine its chemical structure.

Similar threads

  • Atomic and Condensed Matter
Replies
2
Views
1K
  • Atomic and Condensed Matter
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
1
Views
3K
Replies
4
Views
1K
Replies
7
Views
4K
Replies
1
Views
2K
Replies
1
Views
2K
  • Chemistry
Replies
1
Views
6K
  • Biology and Chemistry Homework Help
Replies
1
Views
2K
Replies
3
Views
4K
Back
Top