These defects, which can be formed by irradiating alkali metal halides with X-rays, display energy levels that resemble a three-dimensional square well. For 10 points each:
[10h] Name these extrinsic point defects that are produced when an electron occupies an anion vacancy.
ANSWER: F-centers [prompt on color centers or Fabre centers]
[10e] F-centers typically impart color to crystals that otherwise would have this property of allowing nearly all light to pass through them.
ANSWER: transparent [or transparency; accept diaphaneity or pellucidity]
[10m] Since electrons found in an F-center are unpaired, an F-center’s hyperfine structure can be found using this technique. This technique is also used to examine metal catalytic centers and probe for free radicals.
ANSWER: EPR spectroscopy [or electron paramagnetic resonance spectroscopy; or ESR spectroscopy; or electron spin resonance spectroscopy]
<Kane Nguyen, Chemistry>