Improved rovibrational constants and frequency tables for the normal laser bands of 12C16O2

New frequency difference measurements between Doppler-free stabilized laser lines in the 9.4- and 10.4-μm bands of ¹²C¹⁶O₂, including high-J and across-the-band-center measurements, have made significant improvements in the rovibrational constants. The absolute frequencies were referred to the methane stabilized 3.39-μm HeNe laser. Frequency tables generated from these constants have absolute uncertainties of less than two parts in 10¹⁰ and are about a factor of 10 better than older tables. In addition, the laser lines P_I(50) in ¹³C¹⁶O₂ and R_II(26) in ¹³C¹⁸O₂, which were used as reference lines in recent visible laser frequency measurements, were also measured to about the same accuracy.     

On the proposed existence of an anti-gravity regime in the early universe

In an interesting letter, Linde has recently suggested that, as a result of the behaviour of dense matter in the early Universe, the realization of an anti-gravity phase is possible, in principle, without the intervention of quantum gravity. Using the Friedman cosmological model, we amplify the discussion given by Linde and find a difficulty with his interpretation.     

Lambda polarization in inclusive K−p interactions at 10 and 16 GeV/c

A strong negative transverse polarization P_z is found for forward produced lambdas observed in 10 and 16 GeV/c K^?p interactions. This indicates that exchanges of natural spin-parity are dominant in the production process. Using the polarization results, the $\text{d}\text{σ}\text{d}\text{u′}$ distributions for natural and unnatural spin-parity exchanges are derived. For unnatural exchanges, a dip is observed at u′?0.3 GeV², which can be explained as a nonsense-wrong-signature zero of the N_β trajectory. The value of P_z for forward producted lambdas is constant with energy. This is in agreement with the triple-Regge model prediction, as is the fact that P_z is constant as a function of $\text{M}{}^2\text{s}$. The two non-transverse polarization components, P_x and P_y, have been measured and are found to be consistent with zero for all x values, unlike P_z.     

A measurement of π+p backward elastic differential cross sections from 1.282 to 2.472 GeV/c

New high-statistics measurements of π⁺p elastic scattering differential cross sections are presented at 30 momentum points between 1.282 and 2.472 GeV/c, covering most of the angular distribution outside the forward diffractive peak. These data show significant disagreements at some momenta with previous high-statistics experiments and with current partial wave analyses.     

Optical properties and stable,broadly tunable cw laser operation of new FA-type centers in Tl+-doped alkali halides

A new group of complex color centers with F_A-type properties, involving simple center production and high thermal and optical stabilities, has been found in six Tl⁺-doped alkali halides: NaCl, KCl, RbCl, KBr, RbBr and RbI. In its first tested examples, KCl and KBr, broadly tunable cw laser operation over the 1.4 to 1.7 μm range has been obtained, with output powers in the 100 mW range. In contrast to already existing F⁺₂ and F⁺₂-like centers, operating in the same wavelength range, the new F_A(Tl⁺) lasers are optically stable and do not show any bleaching effects under laser operation.     

Approaching non-destructive surface chemical analysis of CMSX-4 superalloy with double-pulsed laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) was performed on the CMSX-4 Ni-based superalloy using a femtosecond pulsed laser. An orthogonal double-pulse technique was used to minimize surface damage associated with LIBS. With this technique, the depth of ablation craters was reduced from 200 nm for single-pulse LIBS down to less than 60 nm using orthogonal double-pulse LIBS. The technique also allowed the average velocity of the ablated material to be determined, which ranged from 4720 ± 560 m/s at a pump laser fluence of 3.1 J/cm² to 8150 ±1800 m/s at 10.1 J/cm².     

Fluoroarylphosphines as ligands

This short review concentrates on important aspects of fluoroarylphosphines, in particular their synthesis, ligand properties and chemical and catalytic properties of their complexes. Although the electronic, steric and chemical properties of fluoroarylphosphines have been known for 30 years, their use as ligands for homogeneous catalysis and in the synthesis of elaborate multidentate ligands has occurred more recently. The number of recent reports suggests that their importance is growing.     

New Adventures in Thermal Analysis

This paper describes recent advances in thermal analysis instrumentation which combine the high resolution imaging capabilities of the atomic force microscope with physical characterisation by thermal analysis. Images of the surface may be obtained according to the specimen's thermal conductivity and thermal expansivity differences in addition to the usual topographic relief. Localised equivalents of modulated temperature differential scanning calorimetry, thermomechanical and dynamic mechanical analysis have been developed with a spatial resolution of a few micrometres. A form of localised thermogravimetry-evolved gas analysis has also been demonstrated. The same instrument configuration can be adapted to allow IR microspectrometry at a resolution better than the optical diffraction limit. This revised version was published online in August 2006 with corrections to the Cover Date.