The microwave spectrum of MnO3F

The microwave spectrum of MnO₃F has been remeasured and several corrections and new results have been obtained: B₀ = 4129.141 MHz, D_J = 1.12 kHz, D_JK = 1.87 kHz; $\text{α}{}_3{}^{\mathrm{B}}\text{= 8.622}$, $\text{α}{}_5{}^{\mathrm{B}}\text{= ? 11.994}$, $\text{α}{}_6{}^{\mathrm{B}}\text{= 6.042}$, |q₅| = 16.005, and |q₆| = 8.456 MHz.     

Refractive index measurements by probe-beam deflection

Two deflection techniques for the measurement of the dispersive properties of an optical medium have been implemented. Prismatic deflection is used to measure the dispersion of a medium exhibiting Electromagnetically Induced Transparency (EIT) with the cascade system in ⁸⁵Rb and ⁸⁷Rb. In addition, the dispersion associated with a saturated absorption and hyperfine pumping spectrum is measured by deflection due to a spatial inhomogeneity of the refractive index induced by an expanded Gaussian-profile pump beam.Received: 19 December 2003, Published online: 20 April 2004PACS: 39.30. + w Spectroscopic techniques - 33.55.Ad Optical activity, optical rotation; circular dichroismG. Jundt: Present address: Institute of Quantum Electronics, Department of Physics, ETH Zürich, Hönggerberg 8093, Switzerland     

On Idempotent-generated Subsemigroups of Principally Ordered Regular Semigroups

Here we consider, in a principally ordered regular semigroup in which the operation $x \mapsto x*$ is weakly isotone, the structure of the *-subsemigroup that is generated by a pair of comparable idempotents.     

High-throughput screening of pKa values of pharmaceuticals by pressure-assisted capillary electrophoresis and mass spectrometry

A high-throughput pKa screening method based on pressure-assisted capillary electrophoresis (CE) and mass spectrometry (MS) is presented. Effects of buffer type and ionic strength on sensitivity and pKa values were investigated. Influence of dimethyl sulfoxide (DMSO) concentration present in the sample on effective mobility measurement was examined. A series of ten volatile buffers, covering a pH range from 2.5 to 10.5 with the same ionic strength, was employed. The application of volatile background electrolytes resulted in significant signal increase as compared with commonly used non-volatile phosphate buffers. In general, the CE/MS system provided a ten-fold higher sensitivity than conventional UV detection. The newly developed CE/MS method offers high-throughput capacity by pooling a number of compounds into a single sample. Simultaneous measurement of more than 50 compounds was readily achieved in less than 150 min. The measured pKa values are consistent with the published data obtained from the CE/UV method and are also in good agreement with data generated by other methods. Other advantages of using CE/MS for pKa screening are illustrated with typical examples, including poorly soluble compounds and non-UV-absorbing compounds.     

Non-linear Sagnac interferometry for pump-probe dispersion spectroscopy

We explore pump-probe non-linear Sagnac interferometry as a tool to measure the dispersive properties of a medium. We introduce the background theory, and show experimental spectra obtained on the D₂ transition with ⁸⁵Rb and ⁸⁷Rb. The measured dispersion spectra are in excellent agreement with the Kramers-Kronig relations. In addition, as both beams traverse identical optical paths, Sagnac interferometry is very robust against mechanical vibrationReceived: 5 June 2003, Published online: 16 September 2003PACS: 39.30. + w Spectroscopic techniques - 33.55.Ad Optical activity, optical rotation; circular dichroismG. Jundt: Present address: Institute of Quantum Electronics, Department of Physics, ETH Zürich, Hönggerberg 8093, Switzerland.     

Pulsed ytterbium-doped large mode area double-clad fiber amplifier in MOFPA configuration

A pulsed master oscillator fiber power amplifier working in nanosecond range has been developed. An ytterbium-doped double-clad (large mode area) optical fiber was used as an amplifying medium. Actively Q-switched Nd:YVO laser was used as a seed of light pulses. The system worked at the repetition rate from 10 kHz to 40 kHz. At the amplifier output, pulses of 10.9 kW peak-power were achieved. The laser system worked at the slope efficiency of 30%.     

On the application of a single‐crystal κ‐diffractometer and a CCD area detector for studies of thin films

A multipurpose six‐axis κ‐diffractometer, together with the brilliance of the ESRF light source and a CCD area detector, has been explored for studying epitaxial relations and crystallinity in thin film systems. The geometrical flexibility of the six‐axis goniometer allows measurement of a large volume in reciprocal space, providing an in‐depth understanding of sample crystal relationships. By a set of examples of LaAlO₃ thin films deposited by the atomic layer deposition technique, the possibilities of the set‐up are presented. A fast panoramic scan provides determination of the crystal orientation matrices, prior to more thorough inspection of single Bragg nodes. Such information, in addition to a broadening analysis of families of single reflections, is shown to correlate well with the crystallinity, crystallite size, strain and epitaxial relationships in the thin films. The proposed set‐up offers fast and easy sample mounting and alignment, along with crucial information on key features of the thin film structures.     

Chiral lariat ethers as membrane carriers for chiral amino acids and their sodium and potassium salts

Four chiral lariat ethers 8–11 containing a (p-methoxyphenoxy) methyl side arm were used for chiral discrimination of amino acids in their zwitterionic form or as potassium and sodium salts in transport across a bulk chloroform membrane with satisfactory selectivity. The carriers that were employed exhibited different transport selectivity relative to the amino acids and their salts under study. The d/l selectivity strongly depends on the amino acids or their salts, and in some cases reverse selectivity has been obtained. The best selectivity was obtained in the case of tyrosine and its potassium salts for all carriers. The transport rates of amino acids and their salts were found to be controlled by factors such as the structure of the carriers and amino acids or their salts. Among these factors, it was also found that the side arm of the lariat ethers plays an important role in the transport process. As a consequence, the main goal of our investigation was to separate the chiral amino acids through liquid membranes.