LaSe cr

The heat capacity of LaSe(cr) was measured in the temperature range 90 to 390 K by Tikhonov, Golubkov, and Smirnov [67TIK/GOL]. The value obtained at 298.15 K is selected  

No entropy value for LaSe(cr) at 298.15 K was selected from the measurements in [67T1K/GOL] because of the missing experimental information in the temperature range 0 to 90 K. 

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Emerald, Cr " doped beryl, has a beryl structure with the Cr " impurity ions in highly distorted octahedron sites. The discovery of lasing action in emerald stimulated investigation of its luminescence properties. It was established that its tuning range is approximately 730-810 nm, while luminescence consists of a narrow line at 684 nm and a band peaking at 715 nm with similar decay times of 62 ps. The relative intensities of those line and band are different in a- and 7T-polarized spectra (Fabeni et al. 1991). 

The lines at 686 and 693 nm with a long decay time of approximately 1 ms in the titanite emission spectrum are not correlated with any other lines and bands (Fig. 4.34). Such lines are very typical for Cr in a high field coordination and may be connected with such a center. The broad luminescence band appears peaking at 765, which may be ascribed to Cr + in a weak field coordination. The band at 765 nm has distinct dips at 749, 762, 793, 798, 804 and 820 nm. Comparison with the titanite absorption spectrum (Fig. 5.19) demonstrates that those lines exactly coincide with the absorption spectrum of Nd (Bakhtin and Gorobets 1992). Cr is a good energy sensitizer, because it has broad, allowed absorption bands with a broad emission spectrum, which overlaps the absorption bands of the lasing ion (Nd " ", Ho " ). 

In the late 1970s, Cr +-doped alexandrite (BeAl204) was found to lase on the vibrational sideband of the " T2 " A... 

Fig. 3.31. The ruby three-level laser. The pumping nansiiion is 1, the lasing transition 3. The nonradiaiive transition 2 is fast relative to the radiative inverse of 1. The level notations are for Cr +. The orders of magnitude of the relevant rates are p( T2 - Aj) = 10 s .

Caird JA, Shinn MD, Kirchoff TA, Smith LK, Wilder RE (1986) Measurements of losses and lasing efficiency in GSGG-Cr, Nd and YAG-Nd laser rods. Appl Opt 25 4294—4305... 

Saiki T, Nakatsuka M, Imasaki K (2010) Highly efficient lasing action of Nd - and Cr -doped yttrium aluminum garnet ceramics based on phonon-assisted cross-relaxation using solar light source. Jpn J Appl Phys 49 082702... 

The lasing material is distributed in a solid matrix, usually a transparent crystal or glass doped with small amounts of trivalent metal ions (Cr, Nd +)... 

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