Time-resolved study of intramolecular charge transfer fluorescence in 1,2,3,4-tetrachloro-11H-isoindolo-[2, 1-a]-benzimidazol-11-one

Fluorescent properties of 1,2,3,4-tetrachloro-11H-isoindolo-[2,1-a]-benzimidazol-11-one (TCIB) in various organic solutions are described. Detailed investigation of the fluorescence from the solutions revealed that it was ascribable to the electronic transition from the lowest singlet excited state of an isolated molecule to its ground state, though the fluorescence spectrum was broad and structureless and the Stokes’ shift was about 1 eV. The absorption peak of TCIB was relatively insensitive to change in solvent polarity, whereas its fluorescence peak shifted to the red with an increase in the polarity. This finding suggests that the dipole moment of the molecule in the ground state is almost zero, and that the excited state has a non-zero dipole moment, which coincides with the predicted semiempirical molecular orbital calculation. Fluorescence quantum efficiency decreased with increase of solvent polarity. The efficiency was reduced by a factor of 39 in going from n-hexane solution to acetonitrile solution. The radiative rate constant also decreased with increase of solvent polarity. However, its reduction was very moderate; the reduction factor was only 2.5 for acetonitrile solution as compared with n-hexane solution. This finding indicates that the emitting state of the title compound is influenced by a solvent-dependent non-radiative mechanism, for which solvent-sensitive intersystem-crossing deactivation is tentatively proposed.     

An Adaptive Algorithm for Vector Partitioning

The vector partition problem concerns the partitioning of a set A of n vectors in d-space into p parts so as to maximize an objective function c which is convex on the sum of vectors in each part. Here all parameters d, p, n are considered variables. In this paper, we study the adjacency of vertices in the associated partition polytopes. Using our adjacency characterization for these polytopes, we are able to develop an adaptive algorithm for the vector partition problem that runs in time O(q(L)v) and in space O(L), where q is a polynomial function, L is the input size and v is the number of vertices of the associated partition polytope. It is based on an output-sensitive algorithm for enumerating all vertices of the partition polytope. Our adjacency characterization also implies a polynomial upper bound on the combinatorial diameter of partition polytopes. We also establish a partition polytope analogue of the lower bound theorem, indicating that the output-sensitive enumeration algorithm can be far superior to previously known algorithms that run in time polynomial in the size of the worst-case output.     

Chirped-pulse amplification of ultraviolet femtosecond pulses by use of Ce(3+):LiCaAlF(6) as a broadband, solid-state gain medium

Chirped-pulse amplification in the ultraviolet region is demonstrated by use of a broadband Ce(3+): LiCaAlF(6) laser medium. A modified bow-tie-style four-pass amplifier pumped by 100-mJ, 266-nm pulses from a Q -switched Nd:YAG laser has a gain factor of 370 and delivers 6-mJ, 290-nm pulses. After dispersion compensation, the output pulses can be compressed to 115 fs.     

Room-temperature Tm, Ho:LuLiF(4) laser with a novel quasi-end-pumping technique

A novel diode-pumped, efficient, quasi-end-pumping scheme that uses two lens ducts to achieve homogeneous pumping in a gain medium was proposed and evaluated. With this technique, room-temperature laser action at a pulse repetition frequency up to 20 Hz was demonstrated in 5%Tm, 0.5%Ho:LuLiF(4), which we grew by the Czochralski method. At 10 Hz a long-pulse laser output energy in excess of 24 mJ and a slope efficiency with respect to the incident pump energy of 10.7% were obtained.     

Gold-black micropillar electrodes for microfluidic ELISA of bone metabolic markers

Modification with gold black considerably increased the detection current of protruding micropillar electrodes in microfluidic electrochemical enzyme-linked immunosorbent assay (ELISA).     

Tetrahedral Co(II) coordination in alpha-type cobalt hydroxide: Rietveld refinement and X-ray absorption spectroscopy

We report a Rietveld refinement analysis and X-ray absorption study on a green-color Cl(-)-intercalated alpha-type cobalt hydroxide phase. The refinement clearly demonstrated that one-fifth to one-sixth of the Co(II) at octahedral sites was replaced by pairs of tetrahedrally coordinated Co(II) on each side of the hydroxide plane, represented by a structural formula of [Co(octa)(0.828)Co(tetra)(0.348)(OH)2](0.348+)Cl(0.348).0.456H2O. X-ray absorption spectroscopy also indicated that the divalent cobalt were in local neighboring environments of both octahedral and tetrahedral coordination. Furthermore, UV-vis spectroscopic measurements elucidate the typical green/blue color of an alpha-type cobalt hydroxide.     

Skeletal modification of a non-planar phthalocyanine analogue under very mild conditions

A sterically congested tetraphenyl-substituted dibenzo-tetraaza-isobacteriochlorinato nickel derivative unexpectedly reacts with methanol at room temperature to release internal molecular strains, leading to the formation of a ligand having a skeleton bearing two cis-methoxy substituents.