Perkin-Elmer Spectrum One FTIR Spectrometer

The Perkin-Elmer Spectrum One FTIR Spectrometer is capable of data collection over a wavenumber range of 370-7800 cm^-1. It can be configured to run in single-beam, ratio, or interferogram modes. The best resolution is 0.5 cm-¹. A mid-range Deuterated triglycine sulfate infrared detector processes signals with a 68340 integrated chip. The sample compartment is purgeable.

Instrument are interfaced to Perkin Elmer Spectrum software, which gives the user the ability to extract both qualitative and quantitative data from the spectrum, and generate custom reports. See below for specific procedures.

Determining these frequencies allows identification of the sample's chemical make-up, since chemical functional groups are known to absorb radiation at specific frequencies. The intensity of the absorption is related to the concentration of the component. Intensity and frequency of sample absorption are depicted in a two-dimensional plot called a spectrum. Intensity is generally reported in terms of percent transmittance, the amount of light that passes through it.

In the interferometer the light passes through a beam splitter, which sends the light in two directions at right angles. One beam goes to a stationary mirror then back to the beam splitter. The other goes to a moving mirror. The motion of the mirror makes the total path length variable versus that taken by the stationary-mirror beam. When the two meet up again at the beam splitter, they recombine, but the difference in path lengths creates constructive and destructive interference pattern called an interferogram.

1. The instrument and computer are in "always on" mode--it is not necessary to turn them on. Look at the spectrometer indicator panel; there will be all green lights. Make sure the sample compartment is empty. Depress the right switch on the monitor to turn it on and move the mouse to wake up the computer.

If the software is not already running, double click on the Spectrum icon to start the acquisition program. When prompted, log in with your group name followed by the password. The instrument is Spectrum One. Do not activate IR assistant. Press Return or click okay.

2. Enter date, application, user's name, and/or professors name in the instrument log book and comment on any problems. If the software is not already running, double click on the Spectrum Icon to start the acquisition program. When prompted, log and enter the password. Do not activate IR assistant. Press Return or click okay.

3. The program will open and check the hardware. An opening message is titled Accessory Ready Check. It should say System Ready for Use. Click the Cancel button. If there is a spectrum already displayed, click on the Delete icon to clear the window.

4. Obtain a background spectrum for air.

4.1. Make sure the sample area is clean and empty.
4.2. Choose Scan from the Instrument menu drop down list.
4.3. A window titled Spectrum One Scan and Instrument Setup will open. It has several pages accessed by clicking on the tabs. Choose the Sample tab and enter the name background for Name. Next click on the Scan tab and enter Background as the Scan type (under Options in the middle of the page.) All other settings can be left with their default values.
4.4. Click the Apply button, and then the Scan button. The window will refresh, and soon the background scan appears, as it is running. A bar in the lower left corner of the screen shows the progress of the scan. When the scan is complete, a question appears on whether to overwrite the old background scan. Answer Overwrite.
4.5. Click the Delete icon to clear the spectrum window. The background scan is not lost!

5. Obtain the sample spectrum.

4.1. Place the sample in the sample beam either as a KBr pellet or as a thin film on a KBr cell face.
4.2. Choose Scan from the Instrument menu drop down list.
4.3. The Spectrum One Scan and Instrument Setup window will open. Choose the Sample tab and enter a filename appropriate for the sample in the Name line. Fill in the description and comments as required. Then click the Apply button.
4.4 Monitor the progress of the scan as it runs.

5. Analyze and print data.

5.1. Click on the Peaks icon to automatically label all peaks. Clicking a second time removes the labels.

[If necessary adjust the threshold from Process and then Peak Table from the menu drop down list and set a new threshold. Close Peak Table, then click on peaks twice, (once to remove the old labels and again to show the new) then click on the window enlargement box (next to the X in the top right corner of the window frame) to enlarge the image.]

5.2. Zoom a region of the spectrum by dragging a box around the region of interest and then double clicking inside the box. The AutoX and AutoY icons will resize the spectrum to full scale.
5.3. Click on the Text icon to add text to the spectrum. Select a new font or drag the text to a new position after it is written.
5.4. Click on the Print icon to print a copy of the spectrum.
5.5. Click the Delete icon to clear the screen for the next user, or log out if that is appropriate.

6. Clean up
       6.1. Clean the sample area.
       6.2. Using a Kimwipe carefully wipe all the sample off the KBr plates. Place a few drops of chloroform on each of the plates and carefully wipe that off as well. Repeat the chloroform wash once more. Replace the salt plates in their tins and place the tins back into a desiccator. Remove any pellets from the area.
      6.2. Sign out in the instrument log book and record either 'Ok' or note any problems.