TABLE OF CONTENTS The electronic configuration of neutral chromium atoms is (Ar) 3 d 54 s. Trivalent chromium ions with the electron configuration (Ar) 3 d 3 lose their screening shell and the spectrum of the ion, determined by 3 d-electrons, may differ for these ions isomorphously implanted into different matrixes. The interaction of 3 d-electrons of the chromium ions with the electrical fields surrounding them in the matrixes of the active media determines their energy levels. The energy of the spin-orbital interaction for 3 d-ions is approximately 100 cm -1, whereas the energy, determined by the electric field of the crystal, is two orders of magnitude higher. This strong field ruptures the bond between the spin S and the orbital moment L which in this case do not interact which each other. The energy of individual sublevels is determined by the projections of total magnetic moments on the direction of the field and the energy levels are determined by the removal of orbital degeneration with the ratio (2 L + 1) under the effect of the crystal field. In the range of the real crystal fields at the trivalent chromium ion the mutual position of the levels 2 E and 4 T 2 may differ. This makes it possible to produce both narrow-band lasing on R-lines ( 2 E ? 4 A 2 transition) and the lasing rearranged in...
