Production and Application of the Langmuir Aggregates of Eosine with Cetyl Trimethyl Ammonium Bromide

The procedure of microphase adsorption–spectral correction is applied to the interaction of eosine Y (EO) to the micelles of cetyl trimethyl ammonium bromide (CTAB). The Langmuir aggregation of EO on CTAB occurs owing to microelectrostatic attraction. The results have shown that at pH 3.8, monomeric and micellar aggregates have the structure EO₅·CTAB₂ and (EO₅·CTAB₂)₃₉. The adsorption constant of an aggregate is 7.01·10⁵, its molar absorption coefficient is = 8.8·10⁴ liters·mole^–1·cm^–1 at 550 nm. Application of the aggregation of EO on CTAB gives satisfactory results for quantitative determination of cation surfaceactive agents (surfactants).     

Libraries of composite polyfluors built from fluorescent deoxyribosides

We report on a new class of water-soluble fluorescent molecules (polyfluors) that are composed of multiple individual fluorophores assembled on a DNA-like backbone. Four fluorophore deoxyribosides were synthesized, and these individual molecules were assembled into oligofluor strings on a DNA synthesizer. A library of 256 tetrafluors was generated by split and pool methods on polystyrene beads. Images of the library under a fluorescence microscope revealed at least 40-50 different hues and intensities. Selected tetrafluors were resynthesized in pure form in solution and displayed properties, such as large Stokes shifts, that individual fluorophores do not have.     

Electroluminescence in ruthenium(II) complexes

We have investigated the electrochemical, spectroscopic, and electroluminescent properties of a family of diimine complexes of Ru featuring various aliphatic side chains as well as a more extended pi-conjugated system. The performance of solid-state electroluminescent devices fabricated from these complexes using indium tin oxide (ITO) and gold contacts appears to be dominated by ionic space charge effects. Their electroluminescence efficiency was limited by the photoluminescence efficiency of the Ru films and not by charge injection from the contacts. The incorporation of di-tert-butyl side chains on the dipyridyl ligand was found to be the most beneficial substitution in terms of reducing self-quenching of luminescence.     

Dalitz analysis of D0-->K(0)(S)pi(+)pi(-)

In e(+)e(-) collisions using the CLEO detector, we have studied the decay of the D0 to the final state K(0)(S)pi(+)pi(-) with the initial flavor of the D0 tagged by the decay D(*+)-->D0pi(+). We use the Dalitz technique to measure the resonant substructure in this final state and clearly observe ten different contributions by fitting for their amplitudes and relative phases. We observe a K(*)(892)(+)pi(-) component which arises from doubly Cabibbo suppressed decays or D0-D0; mixing.     

Observation of B-->K(0)(S)pi(+)pi(-) and Evidence for B-->K(*+/-)pi(-/+)

We report on a search for charmless hadronic B decays to the three-body final states K(0)(S)h(+)pi(-), K(+)h(-)pi(0), K(0)(S)h(+)pi(0) (h(+/-) denotes a charged pion or kaon), and their charge conjugates, using 13.5 fb(-1) of integrated luminosity produced near sqrt[s]=10.6 GeV, and collected with the CLEO detector. We observe the decay B-->K0pi(+)pi(-) with a branching fraction (50(+10)(-9)(stat.)+/-7(syst.))x10(-6) and the decay B-->K(*+)(892)pi(-) with a branching fraction (16(+6)(-5)(stat.)+/-2(syst.))x10(-6).     

Measurements of the cross section for e(+)e(-) --> hadrons at center-of-mass energies from 2 to 5 GeV

We report values of R = sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->mu(+)mu(-)) for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.     

240-fs pulses with 22-W average power from a mode-locked thin-disk Yb:KY(WO(4))(2) laser

We demonstrate what is to our knowledge the first passively mode-locked thin-disk Yb:KY(WO(4))(2) laser. The laser produces pulses of 240-fs duration with an average power of 22 W at a center wavelength of 1028 nm. At a pulse repetition rate of 25 MHz, the pulse energy is 0.9microJ , and the peak power is as high as 3.3 MW. The beam quality is very close to the diffraction limit, with M(2)=1.1 .