New FIR laser lines and frequency measurements for optically pumped CD3OH

Twenty new cw FIR laser lines in CD₃OH, optically pumped by a CO₂ laser, are reported. The frequencies of 39 of the stronger laser lines were measured relative to stabilized CO₂ lasers with a fractional uncertainty, as determined by the reproducibility of the FIR frequency itself, of 2 parts in 10⁷.Contribution of the U.S. Government, not subject to copyright.     

Working group report: Collider Physics

This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology (WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these problems by the subgroups formed during the workshop is included in this report.     

Tangential chow forms — rank 1 hypersurfaces in a Grassmannian

Let X ⁿ P ^N be an n-dimensional projective variety, and N–n–1kN–1. The closure in the Grassmannian G(k+1, N+1) of the set of k-planes meeting the smooth locus of X nontransversally is a tangential Chow form (TCF) of X.TCF's are generally hypersurfaces. We show that a hypersurface is a TCF iff its conormal form has rank 1, and that a TCF is a hypersurface iff some quadric in the second fundamental form of X has rank n+k+1–N.     

Simulation of the electronic and vibrational structure of hydrogenated amorphous silicon using cluster models

A set of simple models of hydrogenated amorphous silicon (a-Si:H) consisting of hypothetical silane molecules with diamond or similar lattices was studied by the semiempirical AM1 method. Densities of states and infrared spectra were calculated for the silane molecules and similar molecules with dangling bonds disorder, and with boron or phosphorus substitution to simulate doping. Some examples are presented, and a comparison is made with experimental properties of a-Si:H. It is proposed to use these models in a study of the Staebler–Wronski photodegradation of a-Si:H and other aspects of amorphous silicon technology. © John Wiley & Sons, Inc.     

Collisional activation spectra at improved resolving power obtained by the use of a collision chamber and a linked scan of the electric and magnetic sector field strengths

A method for obtaining collisional activation spectra at much higher resolving power than before by use of a collision chamber and a B/E linked scan, is described.     

Titrimetric study of the reaction of chloramine-T with ammonia

A titrimetric study of the reaction between chloramine-T (CAT) and ammonia is described. The effects of the presence of bromide, the ratio of CAT to ammonia concentrations, the time for reaction and the pH of the reaction media are all significant in the quantitativeness of the reaction that occurs.     

Solution kinetics of the degradation of the chemiluminescent reagent bis(2,4-dinitrophenyl) oxalate in water/acetonitrile

Simultaenous ultraviolet absorbance measurements at 240 and 260 nm are used to quantify DNPO and its principle degradation product 2,4-dinitrophenol. The stability of DNPO was determined in various water acetonitrile mixtures (23±0.5°C). The decomposition follows (pseudo)- first-order kinetics in each system, and is third order in water concentration. An Arrhenius plot was used to obtain estimates for the activation energy, activation enthalphy, and activation entropy.