Energy transfer among color centers in LiF crystals

In colored LiF crystals there are many absorption and emission bands which cover a wide region of the spectrum from 200 up to 1 300 nm without breaking the continuity. In the frame of these favourable conditions we have performed some experiments of energy transfer among various color centers. The results indicate the existence of efficient exchanges of radiative energy among several bands by using only one exciting wavelength. In particular, the emissions of the F3 and F − 2 color centers centered at 900 and 1 100 nm, respectively, have been observed by pumping at 672 nm completely outside their absorption bands. PACS. 61.72.Ji Point defects (vacancies, interstitials, color centers, etc.) and defect clusters – 78.40.Ha Other nonmetallic inorganics – 78.55.Fv Solid alkali halides