Two Perkin-Elmer FT-IRs are available for student use. The “Spectrum BX” is a bench-top FT-IR capable of routine mid-IR work (4000 cm-1 to 400 cm-1). The “Spectrum GX” is the larger system with more capabilities. The Spectrum GX can do routine mid-IR work, but is also capable of collecting spectra in the near-IR region (12000 cm-1 to 1800 cm-1). To do near-IR work, the beamsplitter must be changed from KBr to CaF2, and the detector must be changed from the standard room temperature DTGS detector to the liquid nitrogen cooled InSB detector.
The Spectrum GX also has a microscope accessory, with a liquid nitrogen cooled MCT-B detector that covers the range from 4000 cm-1 to 700 cm-1. The microscope accessory can be used in either transmittance or reflectance mode. It can analyze sample regions as small as a few microns square. The position of the microscope’s X-Y stage can be controlled via the data system. The data system can be set up to automatically map the entire surface of a sample.
An ATR accessory (Attenuated Total Reflectance) fits into either the Spectrum BX or the Spectrum GX. It has a ZnSe ATR crystal for solid samples and one for liquid samples. ATR is most useful for sampling the surface of smooth materials that are either too thick or too opaque for transmission IR. Course or abrasive solid samples cannot be done by ATR because they can scratch the ZnSe crystal. The liquid ATR crystal is most useful for analyzing substances in aqueous solution. The massive –OH water band gets attenuated by ATR; sample bands at longer wavelengths become enhanced.
We also have a diffuse reflectance accessory for the Spectrum GX. Diffuse reflectance is useful for powdered materials. The powdered materials should be diluted with KBr prior to running by diffuse reflectance.
Using the FT-IR Equipment
To use the FT-IRs, contact Jim Windak, firstname.lastname@example.org, to schedule a short training class.
The Spectrum BX IR User's Booklet should be printed out and read prior to the training session for the Spectrum BX.
The IR Microscope User's Booklet should be printed out and read prior to the training session for the Spectrum GX microscope.
You must provide a valid shortcode account number for billing your access time on these instruments. Please see billing rates.
The Spectrum BX and the Spectrum GX are located in room 3411 Chemistry.