An Optical Method for Profilometry

Experimental Techniques -     

Clustering phenomena in radioactive and stable nuclei and in heavy-ion collisions

A theory for clustering formation in nuclei and in heavy-ion collisions has been worked out in terms of the quantum-mechanical fragmentation process. Treating the mass fragmentation and relative separation coordinates as weakly coupled, the spontaneous cluster-decay of radioactive nuclei has been considered as a two-step process of clustering formation and tunnelling of the confining nuclear interaction barrier. This model has also been applied to “stable” nuclei, lighter than lead. The effects of adding more and more neutrons to collidingN =Z,A = 4n nuclei are studied for theα-clustering transfer phenomenon.     

The reaction between an azomethine and malonyl dichloride

The reaction of o-hydroxybenzylideneamine and malonyl dichloride produces coumarin-3-carboxanilide.     

Doppler-free heterodyne spectroscopy of Hα. measurement of the 2s12 collisional quenching in gas cell

By applying Doppler-free heterodyne spectroscopy techniques to the hydrogen Balmer-α line (λ = 656 nm), one observes a dramatic improvement in S/N ratios for large detection frequencies, δ. Short-noise limited signals are obtained for δ > 2 MHz. Signal phase shifts yield the first “in situ” measurement of the collisional quenching of the 2s_{$\text{1}\text{2}$} metastable state in gas discharges.     

Chromatographic separations on pyridinium tungstoarsenate-impregnated ion-exchange papers

Ion-exchange papers were prepared by impregnating chromatographic Whatman No. 3 paper with pyridinium tungstoarsenate exchanger. The composition of the material loaded on the paper shows that the compound has the formula (C₅H₅NH)₃ W_{1 2}AsO_{4 0}·R_f values of 30 metal ions were determined on these ion-exchange papers by developing with ascending technique in solvents containing mixtures of n-propanol and hydrochloric or nitric acid. Several binary, ternary and some quaternary separations were also achieved on these papers. Studies were also made on plain papers for comparison.     

A practical, stereospecific route to 18-, 19-, and 20-hydroxyeicosa-5(Z),8(Z),11(Z),14(Z)-tetraenoic acids (18-, 19-, and 20-HETEs)

Suzuki-Miyaura cross-coupling of cis-vinylbromide 6, obtained in three steps from diol 4, with functionalized boranes provides a practical, stereospecific route to the title CYP P450 eicosanoids.     

Large matter effects in numu-->nutau oscillations

We show that matter effects change the numu-->nutau oscillation probability by as much as 70% for certain ranges of energies and path lengths. Consequently, the numu-->nutau survival probability also undergoes large changes. A proper understanding of numu survival rates must consider matter effects in Pmutau as well as Pmue. We comment on (a) how these matter effects may be observed and the sign of Delta31 determined in atmospheric neutrino measurements and at neutrino factories, and (b) how they lead to heightened sensitivity for small theta13.