Excited-state absorption and energy output of laser ruby

The laser performance, luminescence intensity and absorption in excited state of rubies annealed in reducing or oxidizing atmosphere is given. Rubies doped with Mg, Ti or Fe were compared to those containing Cr only. The decrease of energy output is caused by the non-radiative transitions from the excited states to the ground⁴A₂ state. O^– centre developed by the presence of the large ions facilitate the transitions from the upper excited states only, whereas Fe and to a less extent Ti ions make the non-radiative transition from the metastable²E level to the⁴A₂ level possible. Ti³⁺ ions filter also the UV content of the flashlight and prevent the transition from the²E to the higher states.     

Unusual demethylation of 1-dimethylamine-1-carba-closo-dodecarbonate(11)

1-Dimethylamine-1-carba-closo-dodecaborane(1), 1-(CH₃)₂NH-1-CB₁₁H₁₁, can be smoothly demethylated with iodine in weakly alkaline solution to produce 1-methylamine-1-carba-closo-dodecarborane(11), 1-CH₃NH₂-1-CB₁₁H₁₁. The latter compound undergoes formylation with formaldehyde and iodine to give 1-hydroxymethylene-methylamine-1-carba-closo-dodecaborane(11). Further chemical transformations of both compounds are reported.     

Einfluss der Qualität des Rubins auf die Aktiven Parameter des Lasers

The factors influencing the function of Verneuil and Czochralski laser ruby rods are described. Energy output is lowered by O^? colour centre formation, which is typical for the rods containing Mg²⁺ ions. The greater is the optical homogeneity of the rod, the better are the active parameters (including output energy) of the laser.     

The first member of the eleven-vertex azadicarbaborane series, 1,6,9-NC2B8H13, and its N-alkyl derivatives

Reactions between closo-1,2-C(2)B(8)H(10) (1) and amines of general formulation R(1)R(2)NH (where R(1), R(2) = H, H; Me, H; t-Bu, H and Et, Et) resulted in a straightforward cluster expansion and formation of the 11-vertex arachno-azadicarbaboranes of the 1,1-R(1),R(2-)1,6,9-NC(2)B(8)H(11) (2) cluster constitution (where R(1), R(2) = H, H 2a; Me, H 2b; t-Bu, H 2c and Et, Et 2d) in yields 10-75%, depending on the nature of the amine used. The reactions are the first example of a direct closo to arachno transformation in the area of cluster-boron compounds. Compounds 2b and 2c were isolated in two isomeric forms anti- and syn- that differ in the positioning of the t-Bu substituent with respect to the bridging hydrogen site. Deprotonation of compounds 2 generally leads to removal of the bridging proton and formation of the [1,1-R(1),R(2-)1,6,9-NC(2)B(8)H(11)](-) (2-) anions that, in the case of the monoalkylated Me and t-Bu derivatives, adopt only an anti configuration. The structure of anti-2c was determined by X-ray diffraction analysis and the geometries of the parent compound and the corresponding syn and anti isomers were optimised at the RMP2/6-31G* level. The composition of all compounds is consistent with the results of mass spectrometry and multinuclear ((1)H and (11)B) spectroscopy complemented by two-dimensional [(11)B-(11)B]-COSY and (1)H{(11)B(selective)} NMR measurements. Experimental (11)B chemical shifts generally show acceptable agreement with theoretical values calculated by GIAO methods, in particular at GIAO-MP2/II, where possible.     

Structural characterization of nickel-titanium film on silicon carbide

The presented work describes behavior of contact structures of Ni/Ti type on 6H-SiC n-type. The best contact resistivity obtained is 3.3 × 10⁻⁴ Ω cm². The structure showed excellent thermal stability, it was stable after being tested for 10 h at 900 °C. XRD analysis after annealing at 960 °C revealed orthorhombic Ni₂Si as the dominate phase.     

Macropolyhedral boron-containing cluster chemistry. The unique nido-five-vertex-<B2>-nido-ten-vertex conjuncto structure of [(eta5-C5Me5)2Rh2B11H15] via an unexpected cluster-dismantling

B16H20 and [RhCl2(eta5-C5Me5)]2 with tmnd give [(eta5-C5Me5)2Rh2B11H15], which has an unprecedented thirteen-vertex macropolyhedral cluster core based on a nido ten-vertex {MB9} subcluster and a nido five-vertex {MB4} subcluster fused with their open-face {B2} edges in common.