An FT-IR system is most commonly equipped with a Michelson interferometer. Select all of the statements below that are TRUE for a system capable of analyzing the mid-IR region (no partial credit). Group of answer choices A monochromatic IR source is used for excitation of the sample. A chopper is required to modulate the high-frequency IR radiation to the measurable low-frequency range. The laser signal is used to monitor the position of the moving mirror assembly. Zero-retardation always produces constructive interference. After the IR light is passed through the sample, it goes through a narrow slit and to the detector. The laser source must be pulsed at regular intervals