Requiring a net change in a molecule's dipole moment for a vibration to be active, FTP, identify this type of spectroscopy that measures absorbances between 400 and 4000 wave numbers.
Mercury cadmium telluride is frequently used in its detection because it has a smaller band gap than silicon.  Samples are often made into pellets with potassium bromide or deposited on sodium chloride disks.  Requiring a net change in a molecule's dipole moment for a vibration to be active, FTP, identify this type of spectroscopy that measures absorbances between 400 and 4000 wave numbers.
Mercury cadmium telluride is frequently used in its detection because it has a smaller band gap than silicon.  
infrared or IR spectroscopy