Introduction
This page contains spectra that are representative of the normal level of performance of this instrument. A brief description of the acquisition protocol is given for each set of measurements. More detailed information about the proper instrument set-up and operational parameters necessary to reproduce these measurements can be found in the appropriate training manual or application note.
- Interferogram
- Single Beam Energy Curve
- 100 Percent Line
- Polystyrene (thin plastic film)
- Benzophenone (KBr pellet)
Load the MIDIR default set of parameters; do not change any parameters. Be sure that there is nothing in the sample compartment and that a nitrogen purge flow is present. Allow at least five minutes for the sample compartment to purge and for the scanner to warm-up. Use the "Check Signal" tab to view the interferogram. Note that the intensity of the centerburst should be greater than 18,000 counts under these conditions. The position of the centerburst should be 12383 +/- 1, and should be stable.
Load the MIDIR default set of parameters; do not change any parameters. Be sure that there is nothing in the sample compartment and that a purge flow is present. Allow at least five minutes for the sample compartment to purge and for the scanner to warm-up. Acquire a "background" single beam curve (16 scans; 4 wavenumber resolution; 4000 - 400 wavenumber spectral range). A typical single-beam-energy curve is shown below:
Acquire a "background" single beam curve under the conditions mentioned above. Without opening the sample compartment, immediately acquire a second single beam energy curve as "sample". Plot in transmittance mode. Through most of the spectral range above 1000 wavenumbers, the peak-to-peak noise will be less than 0.025%T. A typical result is shown below:
Load the MIDIR default set of parameters. Acquire a "background" single beam curve with nothing in the sample holder. Slide the polystyrene test sample into place in the sample compartment. Acquire the sample single-beam curve and plot the results in transmittance mode.
Press a KBr reference pellet using 100 mg. Press a second pellet by preparing 100 mg of a 1% solid mixture benzophenone in KBr. Acquire a transmittance spectrum using the MIDIR1 parameter set. Plot the C-H stretch region:
Note the fringing representative of the thickness of the pellet. When using our research grade pellet proess,100 mg of KBr typically results in a pellet 0.5mm thick. Fringes will be small in amplitude, but still visible when the dispaly is expanded.
Note that there is no discernible noise in this spectrum. The formula for calculating thickness is:
T(mm) = 5n / (f1-f2), where n is the number of fringes between two frequencies, f1 and f2.