Reflection mass spectrometry

NIRMS = noble-gas-ion reflection mass spectrometry OSEE = optically stimulated exoelectron emission PES = photoelectron spectroscopy PhD = photoelectron diffraction SIMS = secondary ion mass spectroscopy UPS = ultraviolet photoelectron spectroscopy ... 

The result of the Back-to-Basics series is an accumulation of some 50 separate but interrelated expositions of mass spectrometric principles and apparatus. Some areas of mass spectrometry, such as ion cyclotron resonance and ion trap instruments, have not been covered except for passing references. This decision has not been due to any bias by the authors or Micromass but simply reflects the large amount of writing that had to be done and the needs of the greatest proportion of users. 

Other technique—for example, dynamic secondary ion mass spectrometry or forward recoil spectrometry—that rely on mass differences can use the same type of substitution to provide contrast. However, for hydrocarbon materials these methods attain a depth resolution of approximately 13 nm and 80 nm, respectively. For many problems in complex fluids and in polymers this resolution is too poor to extract critical information. Consequently, neutron reflectivity substantially extends the depth resolution capabilities of these methods and has led, in recent years, to key information not accessible by the other techniques. 

Surface analysis has made enormous contributions to the field of adhesion science. It enabled investigators to probe fundamental aspects of adhesion such as the composition of anodic oxides on metals, the surface composition of polymers that have been pretreated by etching, the nature of reactions occurring at the interface between a primer and a substrate or between a primer and an adhesive, and the orientation of molecules adsorbed onto substrates. Surface analysis has also enabled adhesion scientists to determine the mechanisms responsible for failure of adhesive bonds, especially after exposure to aggressive environments. The objective of this chapter is to review the principals of surface analysis techniques including attenuated total reflection (ATR) and reflection-absorption (RAIR) infrared spectroscopy. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) and to present examples of the application of each technique to important problems in adhesion science. 

In secondary ion mass spectrometry (SIMS), a beam of energetic primary ions is focused onto the surface of a solid. Some of the ions are reflected but most of the energy of the primary ions is dissipated in the surface by binary collisions that cause neutrals, excited neutrals, and ions (positive and negative) to be ejected or sputtered from the surface. The secondary ions can be analyzed by a mass spectrometer to provide information about the surface composition of the solid. 

Further structural information is available from physical methods of surface analysis such as scanning electron microscopy (SEM), X-ray photoelectron or Auger electron spectroscopy (XPS), or secondary-ion mass spectrometry (SIMS), and transmission or reflectance IR and UV/VIS spectroscopy. The application of both electroanalytical and surface spectroscopic methods has been thoroughly reviewed and appropriate methods are given in most of the references of this chapter. 

Method abbreviations D-AT-FAAS (derivative flame AAS with atom trapping), ETAAS (electrothermal AAS), GC (gas chromatography), HGAAS (hydride generation AAS), HR-ICP-MS (high resolution inductively coupled plasma mass spectrometry), ICP-AES (inductively coupled plasma atomic emission spectrometry), ICP-MS (inductively coupled plasma mass spectrometry), TXRF (total reflection X-ray fluorescence spectrometry), Q-ICP-MS (quadrapole inductively coupled plasma mass spectrometry)... 

Heinen M, Jusys Z, Behm RJ. 2009. Reaction pathways analysis and reaction intermediate detection via simultaneous differential electrochemical mass spectrometry (DBMS) and attenuated total reflection Bourier transform infrared spectroscopy (ATR-BTIRS). In Vielstich W, Gasteiger HA, Yokokawa H, eds. Handbook of Buel Cells. Volume 5 Advances in Electrocatalysis. Chichester John Wiley Sons, Ltd., in press. 

In this chapter, we have chosen from the scientific literature accounts of symposia published at intervals during the period 1920 1990. They are personal choices illustrating what we believe reflect significant developments in experimental techniques and concepts during this time. Initially there was a dependence on gas-phase pressure measurements and the construction of adsorption isotherms, followed by the development of mass spectrometry for gas analysis, surface spectroscopies with infrared spectroscopy dominant, but soon to be followed by Auger and photoelectron spectroscopy, field emission, field ionisation and diffraction methods. 

State-of-the-art ToF-MS employs reflection lenses and delayed extraction [176] to improve resolution by minimising small differences in ion energies, and in these cases up to 12000 mass resolution (FWHM, m/z 600) is available. This is sufficient for most modern applications. Solid probe ToF-MS (or direct inlet high-resolution mass spectrometry, DI-HRMS) is a breakthrough. DIP-ToFMS is a thermal separation technique. Advantages of DIP-ToFMS are ... 

With recent developments in analytical instrumentation these criteria are being increasingly fulfilled by physicochemical spectroscopic approaches, often referred to as whole-organism fingerprinting methods.910 Such methods involve the concurrent measurement of large numbers of spectral characters that together reflect the overall cell composition. Examples of the most popular methods used in the 20th century include pyrolysis mass spectrometry (PyMS),11,12 Fourier transform-infrared spectrometry (FT-IR), and UV resonance Raman spectroscopy.16,17 The PyMS technique... 

At present, it has only been possible to isolate and identify high concentrations of one compound, isorhamnetin, from pollen of Phleum pretense using high-speed counter-current chromatography. This does not reflect the lack of proper technology, but rather the preparation, time and expense of isolating cryptic and perhaps ephemeral compounds via techniques involving more sophisticated HPLC and mass spectrometry. Consistent with the author s earlier hypothesis that an isorhamnetin class... 

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