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METEORMETRICS LIMITED

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.

DrKFS.net

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

THE SPECTRO-PAEDIA

click on any item in the list for its wikipedia entry if available.


absorbance
adsorption
Atomization
bandwidth
Beamsplitters
bioluminescence
chemiluminescence
chromatography
electroluminescence
electromagnetic
emission
Emissivity
Fluorescence
luminescence
Michelson
monochromators
photo-multiplier
Phosphorescence
photodiodes
photoelectric
photoluminescence
Rayleigh
Raman
spectrofluorometer
spectrometer
spectrophotometer
Spectrum
Transmittance
ultraviolet
Visible
wavelength
Wavenumber
UV Light
Beer's Law
Diode Array
Deuterium Discharge Lamp
Low Pressure Zinc Discharge Lamp
High Pressure Mercury Discharge Lamp
Low Pressure Cadmium Lamp
Tungsten Halogen Lamp
Lens and Window Material in Spectrometers
Cuvettes
Luminescence
Photoluminescence
Fluorescence
Phosphorescence
Bioluminescence
Radioluminescence
Electroluminescence
Fluorescence Reagents
Spectrum
Diffraction Grating
Interferogram
Fourier Transform IR Spectrometer
FT-IR
Halide Disks
Mull Samples
Film Samples for IR Spectroscopy
Light Pipes
Attenuated Total Reflectance Spectroscopy
Multiple Internal Reflectance
External Reflectance
Specular Reflectance
Diffuse Reflectance
Photoacoustic Spectroscopy
Beam Splitter
Raman Scattering
Rayleigh Scattering
Raman Spectroscopy
Atomic Spectroscopy
Atomic Emission Spectroscopy
Atomic Absorption Spectroscopy
The Inductively Coupled Plasma Torch
The Helium Plasma Torch
Emission Spectrometer
Atomic Absorption Spectrometry
Flame Atomic Absorption Spectrometer
Flame AA
Hollow Cathode Lamp
Electrothermal Atomization
Graphite Furnace
L’vov Platform
Electron Paramagnetic Resonance
Zeeman Effect
Continuous Wave
Electron Paramagnetic Resonance
Pulsed EPR
Electron Spin Echo
Multple Resonance Spectroscopy
Magnetic Resonance Spectroscopy
NMR
Precessing
Nucleus Spin Decoupling in NMR
Superconducting Magnets
NMR Microcells
Electron Impact Ionisation
Chemical Ionization
Inductively Coupled Plasma Ionization
Secondary Ion Mass Spectrometry
Fast Atom Bombardment
Plasma Desorption Mass Spectrometry
Laser Desorption Mass Spectrometry
Matrix Assisted Desorption mass Spectrometry
Field Desorption Ionization
Thermospray Ionization
Electrospray Ionization
Atmospheric Pressure Ionization
Particle Beam Interface
Permeable Membrane Interface
Sector Mass Spectrometer
Quadrupole Mass Spectrometer
Ion Trap Mass Spectrometer
Time of Flight Mass Spectrometer
Optical RotationCircular Dichroism
Circularly Polarized Light
Verdet Constant
Faraday Effect
 

An Example of a Commercially Available IR spectrometer

Commercial instruments are available in an number of different arrangements Some are supplied with automatic samplers for the routine analysis of specific sample types, some with near infrared facilities (NIR) and some with microscopy attachments. An example of the Perkin Elmer Spectrum GX system with an associated AutoIMAGE microscope is shown in figure 25. Modern IR spectrometers have high sensitivity and stability and a huge range of options and upgrades providing multi-range and multi-beam facilities. Light spanning from the near infrared to the far infrared is available. Most instruments are modular in form and can cope with up to four equivalent output beams The Perkin Elmer model shown above has ten interchangeable beam splitters, ten different types of detector and alternative configurations include FT Raman, IR microscope and GC-IR interfaces.

Courtesy of the Perkin Elmer Corporation

Figure 25. The Perkin Elmer Spectrum GX Infrared System with an AutoIMAGE microscope.

Spectrum GX Detectors Spectrum GX Beamsplitters

Courtesy of the Perkin Elmer Corporation

Figure 26. Spectrum Range of the GX Detectors and Beam Splitter

The properties of Beam Splitters and detectors are shown in figure 26. Most modern IR instruments have a range of programs to process the IR data collected, a number of which are used to improve sensitivity, resolution and repeatability. The effect of an algorithm that removes the effect of atmospheric absorption from the spectra in real time is shown in figure 27.

Courtesy of the Perkin Elmer Corporation

Figure 27. Effect of Atmospheric Vapour Correction Algorithm on the Background Spectrum

Courtesy of the Perkin Elmer Corporation

Figure 28. The AVI Routine Lowers The Standard Error of Prediction in Quantitative Analysis

Although most IR spectrometers employ a reference laser, the wave number calibration and the line shape is affected by differences in beam divergence and uniformity. In addition differences can occur between instruments when using different sampling techniques and accessories. The Perkin Elmer instrument has a patented Absolute Virtual Instrument (AVI) protocol that improves measurement consistency by standardizing data against small variations in band position and line shape. An example of its use is given in figure 28, which shows the use of AVI to lower the standard error of prediction (SEP) for xylene concentration in the quantitative analysis of liquid mixtures.

Other accessories available are the photo acoustic detector, The FT-IR microscope, the low volume light pipe GC/IR interface and the Near-TR-FT Raman. An example of a high sensitivity application where the Spectrum of a monolayer of cadmium arachidate adsorbed on the surface of silica is obtained by reflectance is shown in figure 29.

Courtesy of the Perkin Elmer Corporation

Figure 29. The IR Reflectance Spectrum of a Monolayer of cadmium Arachinate on silica

 

 

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.

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