Which radiation source is commonly used in X-ray fluorescence spectroscopy?

In interferometry, what does the term "fringe visibility" describe? Which material is commonly used for optical windows due to its high transmission rate in the visible spectrum? Which type of detector is commonly used in gas chromatography? What material property affects the resolution of an optical microscope? What is the purpose of degassing a vacuum system? What is the primary purpose of using a Faraday cage in laboratory experiments? What type of radiation is most effectively blocked by lead shielding? What type of error occurs when equipment is improperly calibrated? What is the purpose of a laboratory's fume hood? What type of pump is commonly used for creating high-vacuum conditions? What is the function of a laboratory thermometer's emergent stem? Which radiation source is commonly used in X-ray fluorescence spectroscopy? In spectroscopy, what does the term "wavenumber" represent? In chromatography, what does the term "retention time" describe?