Radiation and Thermal Transformations of Hydrogen Defects in Li⁶F and LiF:OH

Influence of Neutron Irradiation Conditions on Maximal Frequency of IR Absorption Spectra of LiF:OH Single Crystal

“…[15] Irradiation of LiF with ionizing radiation-X-rays, electrons, ions, extreme UV light, etc.-causes the stable formation of primary and aggregate point defects. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Aggregate F 2 and F 3 þ color centers -two electrons bound to two and three close anion vacancies, respectively-feature visible Stokes-shifted emission in the red (F 2 ) and green (F 3 þ ). [32] As it is well known, the same color center F 2 , F 3 þ (Table 2) are produced in LiF under thermal neutron and γ-ray irradiation at room temperature.…”

“…[36] After irradiation of LiF:OH crystals, hydrogen impurities become sources of additional IR absorption bands at range of 1000-1300 and 1900-2200 cm À1 depending on the irradiation dose and sample preparation details. [12,17,25,37] There are four different types of irradiation-induced hydrogen defects recognized in alkali halide crystals. They are classified according to their position and charge state.…”

“…Second explanation is based on the assumption that the OH À is decomposed under irradiation-forming U 1 defect center. [12,19,25] Note that an increase in the lattice parameter upon irradiation of the crystal weakens the interaction of the resulting defect with the environment. However, the results shown in Figure 5 indicate that the process of interaction of defects formed is more complex.…”

“…[ 15 ] Irradiation of LiF with ionizing radiation—X‐rays, electrons, ions, extreme UV light, etc.—causes the stable formation of primary and aggregate point defects. [ 16–31 ] Aggregate F 2 and F 3 + color centers —two electrons bound to two and three close anion vacancies, respectively—feature visible Stokes‐shifted emission in the red (F 2 ) and green (F 3 + ). [ 32 ]…”

“…Second explanation is based on the assumption that the OH − is decomposed under irradiation‐forming U 1 defect center. [ 12,19,25 ]…”