Irradiated alkali and earth alkali halides can form metal colloids and halogen molecules, which stay trapped inside the crystal. In this paper we provide F NMR spectroscopic evidence of trapped F fluids in heavy ion-bombarded synthesized LiF crystals as well as in a variety of the mineral Villiaumite (NaF). This is the 2nd mineral in which F is unambiguously detected in nature. The trace quantification of the latter is in the order of magnitude of 10 mol g . Pressures and densities of the F fluids are estimated based on the theory of nuclear spin relaxation in dilute gases.
Spatially resolved (19)F and (7)Li spin-lattice relaxation rates are measured for LiF single crystals after irradiation with two kinds of swift heavy ions ((12)C of 133 MeV and (208)Pb of 1.78 GeV incident energy). Like in earlier studies on (130)Xe and (238)U irradiated LiF crystals, we found a strong enhancement of the nuclear spin-lattice relaxation rate within the ion penetration depth and a slight--but still significant--enhancement beyond. By evaluating the nuclear relaxation rate enhancement within the ion range after irradiation with different projectiles, a universal relationship between the spin-lattice relaxation rate and the dose is deduced. The results of accompanying X-band electron paramagnetic resonance relaxation measurements and optical absorption spectroscopy are included in a physical interpretation of this relationship. Also the reason for the enhanced relaxation rate beyond the ion range is further discussed.
Fluorine in Nature Does the aggressive gas F2 exist in nature? In their Communication on page 18388 ff., J. Schmedt auf der Günne et al. discover that the answer to this question is yes. The mineral villaumite is the second example of a fluoride‐based salt that presents a stable enclosure. The F2 gas is produced by radiation damage in different amounts. Its presence was shown, and its pressure was estimated by 19F NMR spectroscopy.
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