Specialising in custom-designed, precision scientific instruments, built, programmed and calibrated to the most exacting standards. The range includes precision dataloging barographs, with built-in statistical analysis, Barographic Transient Event Recorders and computer-interfaced detectors and sensors for environmental monitoring & process control.
A site dedicated to scientific techniques, experimental methods, & investigative tools for the inventor, researcher and laboratory pioneer. Articles on glassblowing, electronics, metalcasting, magnetic measurements with new material added continually. Check it out! www.drkfs.net
click on any item in the list for its wikipedia entry if available.
Fast atom bombardment spectrometry can be considered to be an extension of secondary ion mass spectrometry, and the design of the ionizer is shown in figure 10. A beam of high-energy particles is generated and focused onto the sample, which is held as a thin film on a clean metal surface. The secondary ions are extracted by an appropriate ion optical arrangement into the mass spectrometer analyzer. The impact of a high-energy ion striking the surface produces an intense thermal spike. The energy from this thermal spike is dissipated through the outer layers of the sample. In this innovative device first developed by Barber, neutral atoms of argon and Xenon were employed, but ultimately these were replaced by charged ions such as Ce+ and Xe+.
If a dry sample is used, the surface becomes damaged by the intense energy of the incident beam and the yield of secondary ions is rapidly reduced. However, if the sample is dissolved (or dispersed) in a liquid matrix (e.g. glycerol) the liquid surface is continuously renewed and the high-energy primary beam can be safely used. This method of ionization is now a standard procedure used to obtain the mass spectra of very polar or labile substances. The temperature of the glycerol is critical. At -20˚C the glycerol is too viscous, and cannot dissipate the energy rapidly enough, and at 40˚C the vapor pressure of the glycol is too high and it evaporates in the high vacuum of the source. Optimum sensitivity appears to be realized at a temperature of 25˚C.
About the Author
RAYMOND PETER WILLIAM SCOTT was born on June 20 1924 in Erith, Kent, UK. He studied at the University of London, obtaining his B.Sc. degree in 1946 and his D.Sc. degree in 1960. After spending more than a decade at Benzole Producers, Ltd. Where he became head of the Physical Chemistry Laboratory, he moved to Unilever Research Laboratories as Manager of their Physical Chemistry department. In 1969 he became Director of Physical Chemistry at Hoffmann-La Roche, Nutley, NJ, U.S.A. and subsequently accepted the position of Director of the Applied Research Department at the Perkin-Elmer Corporation, Norwalk, CT, U.S.A.
In 1986 he became an independent consultant and was appointed Visiting Professor at Georgetown
University, Washington, DC, U.S.A. and at Berkbeck College of the University of London; in 1986 he retired but continues to write technical books dealing with various aspects of physical chemistry and physical chemical techniques. Dr. Scott has authored or co-authored over 200 peer reviewed scientific papers and authored, co-authored or edited over thirty books on various aspects of physical and analytical chemistry. Dr. Scott was a founding member of the British chromatography Society and received the American Chemical society Award in chromatography (1977), the M. S. Tswett chromatography Medal (1978), the Tswett chromatography Medal U.S.S.R., (1979), the A. J. P. Martin chromatography Award (1982) and the Royal Society of Chemistry Award in Analysis and Instrumentation (1988).
Dr. Scott’s activities in gas chromatography started at the inception of the technique, inventing the Heat of Combustion Detector (the precursor of the Flame Ionization Detector), pioneered work on high sensitivity detectors, high efficiency columns and presented fundamental treatments of the relationship between the theory and practice of the technique. He established the viability of the moving bed continuous preparative gas chromatography, examined both theoretically and experimentally those factors that controlled dispersion in packed beds and helped establish the gas chromatograph as a process monitoring instrument. Dr. Scott took and active part in the renaissance of liquid chromatography, was involved in the development of high performance liquid chromatography and invented the wire transport detector. He invented the liquid chromatography mass spectrometry transport interface, introduced micro-bore liquid chromatography columns and used them to provide columns of 750,000 theoretical plates and liquid chromatography separations in less than a second. Dr. Scott has always been a “hands-on” scientist with a remarkable record of accomplishments in chromatography ranging from hardware design to the development of fundamental theory. He has never shied away from questioning “conventional wisdom” and his original approach to problems has often produced significant breakthroughs.