Negative ion spectrometry for detecting nitrated explosives

Ionization procedure is modified to produce mainly negative ions by electron capture. Peaks of negative ions are monitored conventionally. Nitrated organic materials could be identified directly from sample sniff inlet stream by suitably modified mass spectrometer because of unique electronegativity which nitro group imparts to organic material

High-pressure Debye-Waller and Grueneisen parameters of Au and Cu

The lattice vibrations are determined in the quasi-harmonic approximation for elemental Au and Cu to twice their normal density by first-principles electronic band-structure calculations. It is found for these materials that the important moments of the phonon density of states can be obtained to high accuracy from short-ranged force constant models. We discuss the implications for the Grueneisen parameters on the basis of calculated phonon moments and their approximations by using bulk moduli and Debye-Waller factors.Comment: 4 pages, 2 figures to appear in the proceedings of the 13th APS Topical Conference on Shock Compression of Condensed Matter (scheduled for April 2004

Automated mass spectrometer/analysis system: A concept

System performs rapid multiple analyses of entire compound classes or individual compounds on small amounts of sample and reagent. Method will allow screening of large populations for metabolic disorders and establishment of effective-but-safe levels of therapeutic drugs in body fluids and tissues

Slabs of stabilized jellium: Quantum-size and self-compression effects

We examine thin films of two simple metals (aluminum and lithium) in the stabilized jellium model, a modification of the regular jellium model in which a constant potential is added inside the metal to stabilize the system for a given background density. We investigate quantum-size effects on the surface energy and the work function. For a given film thickness we also evaluate the density yielding energy stability, which is found to be slightly higher than the equilibrium density of the bulk system and to approach this value in the limit of thick slabs. A comparison of our self-consistent calculations with the predictions of the liquid-drop model shows the validity of this model.Comment: 7 pages, 6 figures, to appear in Phys. Rev.

Automated mass spectrometer analysis system

An automated mass spectrometer analysis system is disclosed, in which samples are automatically processed in a sample processor and converted into volatilizable samples, or their characteristic volatilizable derivatives. Each volatizable sample is sequentially volatilized and analyzed in a double focusing mass spectrometer, whose output is in the form of separate ion beams all of which are simultaneously focused in a focal plane. Each ion beam is indicative of a different sample component or different fragments of one or more sample components and the beam intensity is related to the relative abundance of the sample component. The system includes an electro-optical ion detector which automatically and simultaneously converts the ion beams, first into electron beams which in turn produce a related image which is transferred to the target of a vidicon unit. The latter converts the images into electrical signals which are supplied to a data processor, whose output is a list of the components of the analyzed sample and their abundances. The system is under the control of a master control unit, which in addition to monitoring and controlling various power sources, controls the automatic operation of the system under expected and some unexpected conditions and further protects various critical parts of the system from damage due to particularly abnormal conditions