Hard Drive Microcontamination Testing Services.Quality Control Testing for Manufactured Products.Outgassing Testing Services Prevents Critical Errors.

Materials Characterization & Specialized Testing.Material Testing Services for Products and Components.Cleanliness Testing for Microcontamination.TGA Analysis: Thermal Gravimetric Lab Services.Electron Spectroscopy for Chemical Analysis (ESCA).Gas Chromatography Mass Spectrometry (GC/MS).Fourier Transform Infrared Spectroscopy (FTIR).Differential Scanning Calorimetry (DSC) to Measure Heat Flow.If we were to run a reaction in which we wished to convert cyclohexanone to cyclohexanol, for example, a quick comparison of the IR spectra of starting compound and product would tell us if we had successfully converted the ketone group to an alcohol. IR can also be a quick and convenient way for a chemist to check to see if a reaction has proceeded as planned. In conjunction with other analytical methods, however, IR spectroscopy can prove to be a very valuable tool, given the information it provides about the presence or absence of key functional groups. For this reason, we will limit our discussion here to the most easily recognized functional groups, which are summarized in this table.Īs you can imagine, obtaining an IR spectrum for a compound will not allow us to figure out the complete structure of even a simple molecule, unless we happen to have a reference spectrum for comparison. It is possible to identify other functional groups such as amines and ethers, but the characteristic peaks for these groups are considerably more subtle and/or variable, and often are overlapped with peaks from the fingerprint region. Now, let’s take a look at the IR spectrum for 1-hexanol.Īlkynes have characteristic IR absorbance peaks in the range of 2100-2250 cm -1 due to stretching of the carbon-carbon triple bond, and terminal alkenes can be identified by their absorbance at about 3300 cm-1, due to stretching of the bond between the sp-hybridized carbon and the terminal hydrogen. In the mid-1990’s, for example, several paintings were identified as forgeries because scientists were able to identify the IR footprint region of red and yellow pigment compounds that would not have been available to the artist who supposedly created the painting (for more details see Chemical and Engineering News, Sept 10, 2007, p. The reason for this is suggested by the name: just like a human fingerprint, the pattern of absorbance peaks in the fingerprint region is unique to every molecule, meaning that the data from an unknown sample can be compared to the IR spectra of known standards in order to make a positive identification. While it is usually very difficult to pick out any specific functional group identifications from this region, it does, nevertheless, contain valuable information. This part of the spectrum is called the fingerprint region. You will notice that there are many additional peaks in this spectrum in the longer-wavelength 400 -1400 cm -1 region. Nevertheless, it can serve as a familiar reference point to orient yourself in a spectrum. This peak is not terribly useful, as just about every organic molecule that you will have occasion to analyze has these bonds. The jagged peak at approximately 2900-3000 cm -1 is characteristic of tetrahedral carbon-hydrogen bonds. Within that range, carboxylic acids, esters, ketones, and aldehydes tend to absorb in the shorter wavelength end (1700-1750 cm-1), while conjugated unsaturated ketones and amides tend to absorb on the longer wavelength end (1650-1700 cm -1). Notice how strong this peak is, relative to the others on the spectrum: a strong peak in the 1650-1750 cm -1 region is a dead giveaway for the presence of a carbonyl group. The key absorption peak in this spectrum is that from the carbonyl double bond, at 1716 cm -1 (corresponding to a wavelength of 5.86 mm, a frequency of 5.15 x 10 13 Hz, and a ΔE value of 4.91 kcal/mol).

Ir interpretation chart