Table of Contents
What does an IR graph show?
The IR spectra tell you what types of vibrational modes (motion) the molecule responds with after it absorbs that light, and when you figure out which peaks correspond to which motions, you can figure out what functional groups the molecule has and (almost) what the molecule is.
How do you read FTIR results?
Once the initial testing and spectrum collection is complete, interpretation of FTIR spectra comes next. Typically, interpreting FTIR spectra starts at the high frequency end to identify the functional groups present. The fingerprint regions are then studied to positively identify the compound.
What is a strong peak in IR?
A strong peak around 1450 cm-1 indicates the presence of methylene groups (CH2), while an additional strong peak about 1375 cm-1 is caused by a methyl group (CH3) (examples 1, 8-10).
What is the range of IR spectroscopy?
The infrared range covers 700-1000 nm (wavelength), or 14,286-12,800 cm-1 (wavenumber), and ultraviolet radiation has wavenumbers above these, approximately, 25,000 – 50,000 cm-1, or 100 to 400 nm (wavelength).
What does FTIR spectroscopy detect?
FTIR spectroscopy is used to quickly and definitively identify compounds such as compounded plastics, blends, fillers, paints, rubbers, coatings, resins, and adhesives. It can be applied across all phases of the product lifecycle including design, manufacture, and failure analysis.
Where do alkenes show up on IR?
The C-H wags of alkenes fall in a similar range, between 1000 and 600. To summarize then, the IR spectra of alkenes are characterized by one or more C-H stretching peaks between 3100 and 3000, a possible C=C stretch from 1680 to 1630, and one or more C-H wagging peaks from 1000 to 600.
What does stretch mean in IR spectroscopy?
The absorption of IR radiation causes bonds to stretch and bend. Stretches correspond to the increasing and decreasing of the bondlenghs within a molecule. Bends correspond to the increasing and decreasing of the angle between bonds in a molecule.
What is the range of wavelength?
Visible light has a wavelength range from ~400 nm to ~700 nm. Violet light has a wavelength of ~400 nm, and a frequency of ~7.5*1014 Hz….The EM spectrum.
| Type of Radiation | Frequency Range (Hz) | Wavelength Range |
|---|---|---|
| visible | 4 – 7.5*1014 | 750 nm – 400 nm |
| near-infrared | 1*1014 – 4*1014 | 2.5 μm – 750 nm |