Spectrophotometers for recording spectra in the infra red region consists of an optical system capable of providing monochromatic light in the region of 4000 to 670 cm-1 (about 2.5 to 15mm) or in some cases down to 200cm-1 (50mm) and a means of measuring the Quotient of the intensities of the transmitted light and the incident light.
1.1 Resolution Performances of the Apparatus:
The instrument used for recording infrared spectra should comply with the following test for resolution. Record the spectrum of the polystyrene film 0.05mm thick. The depth of the through from the maximum absorption at 2851 cm-1 (3.51mm) to the minimum at 2870 cm-1 (3.48mm) should be greater than 18% transmittance and that from the maximum at 1583 cm-1 (6.23mm) to the minimum at 1589 cm-1 (6.29mm) should be greater than 12% transmittance.
Verification of the wave-number scale
The wave number scale may be verified using a polystyrene film which has maxima at the wave-number (in cm-1) 8 hours.
The numbers in parentheses indicate the accuracy with which these values have been established.
1.1 F:Sxxxx/ICR - Infra red Spectrophotometer Calibration Record.