The dihedral angle of 2-(trifluoromethyl)phenothiazine

The structure of 2-(trifluoromethyl)phenothiazine, C₁₃H₈NSF₃, was determined by single crystal X-ray diffraction. The molecule crystallizes in space group P2₁2₁2₁, with a = 7.766(2), b = 5.957(1), and c = 23.499(5)Å. The final R value is 0.073. The CSC bond angle is 102.0°, the CNC bond angle is 124.8°, and the dihedral angle between the phenylene planes is 171.2(1)°. The hydrogen atom bonded to the nitrogen atom was located; it is on the inside of the butterfly angle and the S…N? H bond angle is 173.3°.     

A Note on Partial Parallel Classes in Steiner Systems

A partial parallel class of blocks of a Steiner system S(t,k,v) is a collection of pairwise disjoint blocks. The purpose of this note is to show that any S(k,k+1,v) Steiner system, with v?k⁴+3k³+k²+1, has a partial parallel class containing at least (v?k+1)/(k+2) blocks.     

All-optical optomechanics: an optical spring mirror

The dominant hurdle to the operation of optomechanical systems in the quantum regime is the coupling of the vibrating element to a thermal reservoir via mechanical supports. Here we propose a scheme that uses an optical spring to replace the mechanical support. We show that the resolved-sideband regime of cooling can be reached in a configuration using a high-reflectivity disk mirror held by an optical tweezer as one of the end mirrors of a Fabry-Perot cavity. We find a final phonon occupation number of the trapped mirror n=0.56 for reasonable parameters, the limit being set by our approximations, and not any fundamental physics. This demonstrates the promise of dielectric disks attached to optical springs for the observation of quantum effects in macroscopic objects.     

Milchs?ure

Ohne Zusammenfassung