Branching ratio measurement of the decay K(L) --> e(+)e(-)mu(+)mu(-)

We have collected a 43 event sample of the decay K(L)-->e(+)e(-)mu(+)mu(-) with negligible backgrounds and measured its branching ratio to be (2.62+/-0.40+/-0.17)x10(-9). We see no evidence for CP violation in this decay. In addition, we set the 90% confidence upper limit on the combined branching ratios for the lepton flavor violating decays K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+) at B(K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+))< or =1.23x10(-10), assuming a uniform phase space distribution.     

Radiative decay width measurements of neutral kaon excitations using the primakoff effect

We use K(L)'s in the 100-200 GeV energy range to produce 147 candidate events of the axial vector pair K1(1270)-K1(1400) in the nuclear Coulomb field of a Pb target and determine the radiative widths Gamma(K1(1400)-->K0+gamma)=280.8+/-23.2(stat)+/-40.4(syst) keV and Gamma(K1(1270)-->K0+gamma)=73.2+/-6.1(stat)+/-28.3(syst) keV. These first measurements appear to be lower than the quark-model predictions. We also place upper limits on the radiative widths for K(*)(1410) and K(*)(2)(1430) and find that the latter is vanishingly small in accord with SU(3) invariance in the naive quark model.     

The growth of a single crystal of Sr3CuIrO6 and its magnetic behavior compared to polycrystals

We have grown single crystals of the psuedo-one-dimensional compound Sr₃CuIrO₆, a K₄CdCl₆-derived monoclinic structure with Cu-Ir chains along the [101] direction. We present the ac and dc magnetization behavior of the single crystals in comparison with that of the polycrystalline form reported earlier. There is a distinct evidence for at least two magnetic transitions, at 5 K (T ₁) and 19 K (T ₂), with different relative magnitudes in the single and polycrystals. The low temperature magnetic relaxation behavior of both the forms is found to be widely different, exhibiting unexpected time dependence.     

Metabolism of trimethylarsine oxide

Trimethylarsine oxide [(CH₃)₃AsO] has been shown to be easily reducible by various biological species, including both aerobic and anaerobic micro-organisms, some skin organisms, soil bacteria, sludge and rumen fluid. The results suggest an enhanced mobility for arsenic owing to facile production of the volatile (CH₃)₃As species.     

Synthesis of oligodeoxynucleotides and oligodeoxynucleotide analogs using phosphoramidite intermediates

The synthesis of two deoxyoligonucleotides, d(G-T-G-A-G-T-T-A-G-C-T-C-A-C) and d(G-T-G-A-G-C-T-A-A-C-T-C-A-C), corresponding to the DNA binding site for cyclic AMP receptor protein is reported. These syntheses have been completed in milligram quantities using a silica gel polymer support methodology and mononucleotide phosphoramidites. Procedures are also reported for synthesizing diastereoisomers of dinucleoside methylphosphonate 3$\text{-}\text{?}$phosphoramidites.     

Radical pair in crystalline dibenzoyl peroxide evidence for triplet ground states

Zero-field splitting (zfs) tensors and g tensors are reported for two phenyl-benzoyloxyl radical pairs (PB5K and PB15K) and two benzoyloxyl-benzoyloxyl pairs (BB10K and BB25K) in photolyzed single crystals of dibenzoyl peroxide. The g tensors show that in three of the pairs a benzoyloxyl radical has undergone in-plane rotation by about 40°. In PB15K this motion relieves steric repulsion from a CO₂ molecule, and it is suggested that motion in the BB pairs relieves repulsion between radical oxygens in a ground-state triplet radical pair. Spin-orbit coupling is necessary to explain the zfs of PB5K. This explanation requires that the triplet of the electronically excited radical pair lie below the corresponding singlet by an amount which is significant in comparison to the excitation energy. The source of singlet-triplet splitting is discussed briefly and simple VB calculations are shown not to support the above interpretation, although the STO3G and 4-31G basis sets employed are very likely inadequate. Atomic coordinates are reported for crystalline dibenzoyl peroxide.