Damage and track morphology in LiF crystals irradiated with GeV ions

Magnetic resonance investigation of the dynamics of F centers in LiF

“…Using an oscillator strength of 0.8, we determined the concentration of the F centers (N F ) using the Smakula±Dexter formula [9,11] N F 9:48 £ 10 15 cm 22 A=d; 3…”

“…The color centers in LiF irradiated with g-rays and electrons are distributed randomly and correspond to F and F 2 centers and their complementary V centers (absorption at 114 nm in the VUV). Only at doses higher than 1 MGy, the complex color centers (F n centers with n $ 3) have a noticeable contribution to the absorption in the range of 200±500 nm [1,9]. The irradiated crystals color ranging from yellow through brown to black, depending on the concentration of the defects.…”

F centers in LiF: A nuclear magnetic resonance study

“…The g-photons, which were taken from a 60 Co decay (energy E = 1.17 and 1.33 MeV, dose D = 1 kGy À 5 MGy) and the electrons (E = 20 MeV, D = 100 kGy) create a homogeneous distribution of defects. In contrast irradiation with swift heavy ions like 208 Pb (E = 29 MeV/u) causes an inhomogeneous distribution [15,[20][21][22] consisting of a core region of 2-4 nm diameter around the ion track, where the high defect concentration leads to aggregates of defects and Li clusters, while the halo region with a diameter of 20-30 nm contains mostly F centers and their agglomerates [15,23].…”

“…As these studies have shown, the F center EPR spectra show orientation dependent hyperfine splittings due to the interaction with the neighboring lithium and fluorine atoms. The optical spectra were investigated, and the density of the different kinds of crystal defects like F, F 2 or F 3 centers can be determined from the intensity of the respective absorption lines [4,15,17,18]. Some dynamical studies and annealing experiments were performed [1,19], which show that the F centers are stable at room temperature, but recombine at temperatures higher than 360 K [19].…”

“…electrons at an empty anion site, are formed relatively easily. F centers in alkali halides have widely been studied over the last fifty years [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] by optical absorption spectroscopy, nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), and other techniques. As these studies have shown, the F center EPR spectra show orientation dependent hyperfine splittings due to the interaction with the neighboring lithium and fluorine atoms.…”