PPT Slide
- Because of the complicated nature of the signal, it must be converted back to a spectrum by a computer. This is the FOURIER TRANSFORM.
- On most instruments, you may observe the raw data, i.e the interferogram. This can be useful for troubleshooting. For example, the peak - to peak distance ( in volts ) is a measure of the quality of spectrum you will get.
- The FTIR is a single beam spectrometer. That is, it does not automatically measure a background for you. You should measure a background spectrum before your sample. As the sample and background are collected separately, a laser ( usually HeNe at 632 nm ) is used to ensure the background and sample frequencies are identical.