Asymmetric Gold‐Catalyzed Lactonizations in Water at Room Temperature

Asymmetric gold‐catalyzed hydrocarboxylations are reported that show broad substrate scope. The hydrophobic effect associated with in situ‐formed aqueous nanomicelles gives good to excellent ee’s of product lactones. In‐flask product isolation, along with the recycling of the catalyst and the reaction medium, are combined to arrive at an especially environmentally friendly process.     

Complex dynamic behavior of fluctuating smectic- A films as studied by scattering with coherent X-rays

Coherent dynamic x-ray scattering has been used to study the thermally excited layer fluctuations in freely suspended smectic films of the compound 4O.8. Using 8-keV x rays and films with a thickness around 0.3 &mgr;m we resolve relaxation times down to a few &mgr;s. A combination of damped and oscillatory behavior is observed for the layer undulations, which can be attributed to inertial effects. These are due to the surface contribution to the free energy which cannot be disregarded for thin films.     

Studies of coupled molybdate and tungstate vibrations

The polarized Raman and infrared reflection spectra of molybdate and tungstate compounds of barium and strontium are presented and analyzed. The longitudinal and transverse frequencies of the infrared active phonons were calculated by a Kramers-Kronig analysis of the reflection curves. A strain induced forbidden mode was observed in the reflection spectra that gives interpretation of the strong shoulder on the ν₃ bands in the absorption spectra of mulled samples. The correlation field splittings of the internal modes were analyzed in terms of dipole-dipole interaction theory. The correlation field splittings of the ν₃ modes were found to be explainable in terms of dipolar coupling alone, while the splittings of the ν₂ and ν₄ modes could not be accounted for in terms of dipolar coupling.     

Computing the arithmetic genus of Hilbert modular fourfolds

The Hilbert modular fourfold determined by the totally real quartic number field is a desingularization of a natural compactification of the quotient space , where PSL acts on by fractional linear transformations via the four embeddings of into . The arithmetic genus, equal to one plus the dimension of the space of Hilbert modular cusp forms of weight , is a birational invariant useful in the classification of these varieties. In this work, we describe an algorithm allowing for the automated computation of the arithmetic genus and give sample results.

     

Detection and imaging of He2 molecules in superfluid helium

We present data that show a cycling transition can be used to detect and image metastable He2 triplet molecules in superfluid helium. We demonstrate that limitations on the cycling efficiency due to the vibrational structure of the molecule can be mitigated by the use of repumping lasers. Images of the molecules obtained using the method are also shown. This technique gives rise to a new kind of ionizing radiation detector. The use of He2 triplet molecules as tracer particles in the superfluid promises to be a powerful tool for visualization of both quantum and classical turbulence in liquid helium.     

Characterizing dissolved organic matter fractions using spectral fluorescent signatures and post processing by principal component analysis

Using modern computer enhanced control and acquisition systems, it is possible to process and analyze the entire usable portion of a spectral region in a reasonable amount of time. This paper describes the creation of a three dimensional fluorescent spectral library of dissolved organic matter (DOM) fractions in water obtained by solid phase adsorption. Although analysis of the response surface and the emission characteristics can be documented manually, this process is subjective in nature and prone to errors. A more efficient method is to conduct post processing using multi-variate analysis of the response surface to identify specific characteristics of the sub-fraction of DOM in water.     

A Conversation with Valentine L.Telegdi – Part I

The Hungarian experimental physicist Valentine L.Telegdi, who died on April 8, 2006, recalls his early interest in physics and chemistry; his education as a chemical engineer at Lausanne University and eventual turn toward experimental physics; and his graduate work at ETH, the Swiss Federal Institute of Technology (Ph.D. 1950). Goes to the University of Chicago in 1951; recollections of Enrico Fermi, Murray Gell-Mann, Leo Szilard, and other colleagues there. Recalls his work with Jerome Friedman on parity violation in muon decay and his work at CERN with Richard Garwin. Discouraged with state of physics in Chicago, he returns to ETH in 1976, with a joint appointment at CERN. Begins regular visits to Caltech in 1981; compares the style of teaching and research there with his European experience. Discusses his 1987 festschrift at CERN; Gell-Mann’s 1989 festschrift at Caltech; recollections of Richard Feynman, Gell-Mann, Edward Witten. Comments on current state of particle physics.