Time-of-flight spectroscopy

Sputter-Initiated Resonance Ionization Spectroscopy Surface Analysis by Resonant Ionization Spectroscopy Time-of-Flight Mass Spectrometer... 

The identifications of atomic and molecular species is undertaken with a variety of mass spectroscopies. Time-of-flight (TOF) mass spectroscopy is of value for very short lived or highly peaked emissions. More sustained emissions are more readily studied with a quadrupole mass spectrometer (QMS), which can be tuned to a single mass peak. The time evolution (on a microsecond time scale) of a particular mass emission can be determined from the observed signals. Under the appropriate conditions, both these tools can be applied to studies of neutral emission (with ionizer) and positive or negative ion emission (without ionizer). 

Trimethylol propane triacrylate Trimethylol propane trimethacrylate Tetramethyl thiuram disulphide Total correlation spectroscopy Time-of-flight MS Thermoplastic elastomer(s)... 

On the basis of the combined results of X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and atomic force microscopy, the ODP molecules are proposed to preferentially coordinate to tantalum cations via both monodentate and bidentate complexation, leading to 7-fold site coordination, a preferred coordination number for Ta(V). A further stabilization of the ODP layer by intermolecular hydrogen bonding between monodentate and bidentate molecules is also likely to occur in such a model. 

Keywords Surface analysis X-ray photoelectron spectroscopy Time-of-flight secondary ion mass spectroscopy Attenuated total reflection infrared spectroscopy Zinc dialkyidithiophosphate Combinatorial methods In situ methods Tribochemistry... 

Laser-induced plasma spectroscopy Time-of-flight secondary ion mass spectrometry... 

See also Atmospheric Pressure Ionization in Mass Spectrometry Biochemical Applications of Mass Spectrometry Chromatography-MS, Methods Laboratory Information Management Systems (LIMS) Nucleic Acids and Nucleotides Studied Using Mass Spectrometry Proteins Studied Using NMR Spectroscopy Time of Flight Mass Spectrometers. 

The analytical tool selection for characterizing sihcone surface modification for biomedical apphcation is critical. The surface chemistry should be analyzed after every surface modification for the quantity and the quahty of the attached bioactive compound. The techniques of contact angle. X-ray photoelectron spectroscopy, time of flight secondary ion mass spectrometry (ToF-SlMS), and atomic force microscopy (AFM) have been successfully implemented on silicone surfaces as discussed in this section. 

Several experimental techniques can be used to study surfaces. X-ray Photoelectron Spectroscopy (XPS), Auger Spectroscopy, X-ray Absorption Spectroscopy, Low Energy Electron Diffraction (LEED), Infra-Red spectroscopy (IR), Raman spectroscopy. Time of Flight Secondary Ionization Mass Spectroscopy (ToF-SIMS), different microscopy techniques, cyclic voltammetry and many other methods have been used to understand the chemical composition and also the reactivity of many sulfide surfaces. However, any analysis using these methodologies are not limited to surface atoms and contributions from the bulk phase are also included. In LEED, for example, in which the incident electrons are elastically backscattered from a surface and subjected to diffraction, the electrons can travel around 5-20 A into the solid. This will make any spectra analysis very difficult and, sometimes, not conclusive. 

Time-of-flight mass spectrometers have been used as detectors in a wider variety of experiments tlian any other mass spectrometer. This is especially true of spectroscopic applications, many of which are discussed in this encyclopedia. Unlike the other instruments described in this chapter, the TOP mass spectrometer is usually used for one purpose, to acquire the mass spectrum of a compound. They caimot generally be used for the kinds of ion-molecule chemistry discussed in this chapter, or structural characterization experiments such as collision-induced dissociation. Plowever, they are easily used as detectors for spectroscopic applications such as multi-photoionization (for the spectroscopy of molecular excited states) [38], zero kinetic energy electron spectroscopy [39] (ZEKE, for the precise measurement of ionization energies) and comcidence measurements (such as photoelectron-photoion coincidence spectroscopy [40] for the measurement of ion fragmentation breakdown diagrams). 

Laser ionization mass spectrometry or laser microprobing (LIMS) is a microanalyt-ical technique used to rapidly characterize the elemental and, sometimes, molecular composition of materials. It is based on the ability of short high-power laser pulses (-10 ns) to produce ions from solids. The ions formed in these brief pulses are analyzed using a time-of-flight mass spectrometer. The quasi-simultaneous collection of all ion masses allows the survey analysis of unknown materials. The main applications of LIMS are in failure analysis, where chemical differences between a contaminated sample and a control need to be rapidly assessed. The ability to focus the laser beam to a diameter of approximately 1 mm permits the application of this technique to the characterization of small features, for example, in integrated circuits. The LIMS detection limits for many elements are close to 10 at/cm, which makes this technique considerably more sensitive than other survey microan-alytical techniques, such as Auger Electron Spectroscopy (AES) or Electron Probe Microanalysis (EPMA). Additionally, LIMS can be used to analyze insulating sam-... 

Chapter 12, Structure Determination Mass Spectrometiy and Infrared Spectroscopy—A new Section 12.4 discusses mass spectrometry of biological molecules, focusing on time-of-flight instruments and soft ionization methods such as MAI.DI. 

The molecular weights and molecular weight distributions (MWD) of phenolic oligomers have been evaluated using gel permeation chromatography (GPC),23,24 NMR spectroscopy,25 vapor pressure osmometry (VPO),26 intrinsic viscosity,27 and more recently matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).28... 

The anion 19 has been generated by high-energy collision of the p-pentazoylphenolate anion with an inert gas [109] and by laser desorption ionization time-of-flight mass spectroscopy of sohd p-dimethylaminophenylpentazole [110]. N AsP, NjSbF, and [Nj]jSnF have been used by Gordon, Christe et al. [Ill] in their attanpt to observe N F. 

The brief history, operation principle, and applications of the above-mentioned techniques are described in this chapter. There are several other measuring techniques, such as the fluorometry technique. Scanning Acoustic Microscopy, Laser Doppler Vibrometer, and Time-of-flight Secondary Ion Mass Spectroscopy, which are successfully applied in micro/nanotribology, are introduced in this chapter, too. 

Considering these situations, the observation of molecular weights, particularly by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MASS), is essential [33]. The operation is simple and enables us to observe the molecular ion peaks of CPOs with molecular weights exceeding 10,000. The quahty of the measurement is strongly dependent on the choice of the matrix. Therefore, the search for the best matrix for each CPO should be pursued. 

Figure 1. Schematic illustration of the laser-vaporization supersonic cluster source. Just before the peak of an intense He pulse from the nozzle (at left), a weakly focused laser pulse strikes from the rotating metal rod. The hot metal vapor sputtered from the surface is swept down the condensation channel in dense He, where cluster formation occurs through nucleation. The gas pulse expands into vacuum, with a skinned portion to serve as a collimated cluster bean. The deflection magnet is used to measure magnetic properties, while the final chaiber at right is for measurement of the cluster distribution by laser photoionization time-of-flight mass spectroscopy.

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