IR 공부 해보자

https://m.blog.naver.com/PostView.naver?isHttpsRedirect=true&blogId=bkpark777&logNo=220897822854 

Infrared spectroscopy ; stretching, scissoring, rocking, wagging, twisting ; absorbance, reflectance, transmittance

 

 

https://orgchemboulder.com/Spectroscopy/irtutor/alkenesir.shtml

IR: alkenes

 

https://chem.pg.edu.pl/documents/175230/54717567/7.%20IR.pdf

 

7. IR.pdf

3.11MB

 

FTIR stands for Fourier Transform Infrared Spectroscopy. It is a technique used to obtain an infrared spectrum of absorption or emission of a solid, liquid, or gas. Let's break down the process and its importance:

1. Principle: FTIR operates on the principle that molecular vibrations will absorb specific frequencies of infrared (IR) light. When IR radiation is passed through a sample, certain frequencies of the radiation are absorbed by the sample, causing molecular vibrations (stretching or bending). The resulting spectrum represents the molecular absorption and transmission, creating a molecular fingerprint of the sample.

2. Fourier Transform: Traditional IR spectroscopy used dispersive techniques, where individual wavelengths were measured one at a time. This was time-consuming. FTIR, on the other hand, measures all wavelengths simultaneously. It does this by using a Michelson interferometer, which produces an interference pattern called an interferogram. This raw data is then mathematically transformed using the Fourier transform to produce the spectrum.

3. Applications:
• Qualitative Analysis: Since every molecule has a unique infrared absorption spectrum, FTIR can be used to identify unknown materials by comparing their spectra with a database of known spectra.
• Quantitative Analysis: FTIR can also measure the amount of a particular compound in a sample.
• Functional Group Identification: Specific groups in a molecule (like carbonyl, hydroxyl, etc.) absorb IR at characteristic frequencies, so FTIR can determine which functional groups are present in the molecule.
• Study of Reaction Kinetics: By monitoring the decrease or increase in specific peaks over time, one can study the progress of reactions.
• Structural Analysis: Provides insight into the molecular structure and environment of a sample.

4. Advantages:
• Speed: Due to simultaneous measurement of all frequencies, FTIR can be very fast.
• Sensitivity: Modern FTIR instruments have a high signal-to-noise ratio.
• Versatility: Can be used for solids, liquids, and gases.
• Non-Destructive: In many cases, the sample can be recovered with little to no alteration.

5. Components:
• Infrared Source: Produces the IR radiation.
• Michelson Interferometer: Produces the interferogram.
• Sample Compartment: Holds the sample.
• Detector: Measures the transmitted radiation.
• Computer: Converts the raw data into a spectrum.

6. Types of Sample Handling:
• Transmission: Involves passing IR radiation through the sample and measuring the transmitted light.
• Reflectance: Measures the light reflected off the sample, useful for examining surface characteristics.
• Attenuated Total Reflectance (ATR): An internal reflection technique where the sample is in direct contact with a crystal, making it especially useful for solids and viscous liquids.

FTIR spectroscopy is a fundamental tool in many research areas, including chemistry, materials science, and biology, because of its ability to provide detailed molecular information in a non-destructive manner.