Time-of-flight secondary ion mass spectrometer

Fig. 45—The schematic of a Time-of-Flight Secondary Ion Mass Spectrometer.

A few SIMS and SNMS instruments for surface analysis187-189 are commercially available on the analytical market. These are SIMS instruments using a double-focusing sector field mass spectrometer (e.g., CAMECA IMS-7f), time-of-flight secondary ion mass spectrometers (ToF-SIMS IV from CAMECA, Cedex, France, or ToF-SIMS 5, the ToF-SIMS 300 from ION-TOF, Munster, Germany and the PHI TRIFT IV from Physical Electronics, USA) and quadrupole based SIMS (SIMS 4550 and 4600 CAMECA, Cedex, France) or the quadrupole based SNMS instruments with SIMS option (INA-X, SPECS GmbH, Berlin, Germany). 

Transportation of Li in the electrolyte through the SEI may occur via several different mechanisms. One possible mechanism is that Li after desolvation directly passes through pores since SEI is porous the other possibility is that Li after desolvation exchanges with Li in the SEI. Recently, Harris et al. provided a more detailed description of ion transport mechanisms in SEI film by using isotope-labeled electrolyte approach [71]. They immersed three copper electrodes which were preformed SEI in LiC104 EC/DEC electrolyte into 1 M LiBp4 EC/DEC electrolyte for 30 s, 3 min, and 15 min. After immersion, the electrodes were rinsed with DMC solvent and then transferred under Ar to a time-of-flight secondary ion mass spectrometer (TOF-MS) the results are shown in Fig. 5.24. 

Niehuis, E., Heller, T., Feld, H., and Benninghoven, A. (1987) Design and performance of a reflectron based time-of-flight secondary ion mass spectrometer with electrodynamic primary ion mass separation. J. Vac. Sci. TechnoL, A5,1243-1246. 

Bush, K.L. Mullis, J.O. Chakel, J.A. High-resolution imaging of samples in thin layer chromatograms using a time-of-flight secondary ion mass spectrometer. J. Planar Chromatogr.-Mod. TLC 1992,5,9-15. 

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) Measurements. Secondary ion mass spectra were recorded on a PHI 7200 time-of-flight secondary ion mass spectrometer (Physical Electronics, Eden Prairie, MN) in the... 

The time-of-flight secondary ion mass spectroscopy (ToF-SIMS) analysis was performed on a CAMECA ION-TOF Model IV spectrometer. This instrument was equipped with a reflection-type ToF mass analyzer and a pulsed 25 kV primary... 

Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a surface analysis technique used to analyze mass and image constituents that are present on the surface of materials. The equipment (Figure 12.47) uses a pulsed primary ion beam to desorb and ionize species from the sample surface. The resulting secondary ions are accelerated into a mass spectrometer and analyzed by measuring the ToF from the sample surface to the deteetor. The location and distribution of the species on the surface can be identified and an image shown at the detector. The composition is determined from the mass spectrum. Many different primary sources can be used for ionization ... 

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is an extremely surface-sensitive analytical technique that uses a beam of hquid metal ions to probe the top one to three molecular layers of a sample, causing the emission of ions from the sample to be detected in a time-of-flight mass spectrometer, which gives detailed information about the specific molecules and atoms at a surfiice. 

Chemical bond information for materials can be determined with inferred and/or Raman spectroscopy, SIMS (second ion mass spectroscopy) and TOF-SIMS (time-of-flight secondary ion mass spectroscopy). Chemical bond information, especially on the materials surfaces, can be obtained with TOF-SIMS. Micro-IR and micro-Raman spectroscopes have been developed to map the chemical compositions of samples on a micrometer scale. The chemical species presented in MEAs after different lifetime tests were studied by a Raman spectrometer [36]. Cheng and co-workers observed a significant shift in the Raman bands of ruthenium oxide (RUO2) from 528, 646, and 716 cm in a single crystal to 506, 616, and 675-680 cm of amorphous ruthenium oxide at the anode side of MEAs. Although the RUO2 was initially present in the powder sample of the anode... 

Figure 2.12 illustrates the mass spectrum of a narrow-dispersed polystyrene sample recorded using a Secondary Ion Mass Spectrometer equipped with a time-of-flight detector (TOF-SIMS). There are a series of mass spectral peaks due to ions of the type H-(St) -C4H9, Ag (silver was added as a cationization agent). Equahon (2.1) yielded Mn = 4550, which is within 8% with the value Mn = 4964 obtained by VPO. 

The TOF SIMS instrument design is based on the flight time of the secondary ions. A pulsed primary beam impacts a sample surface and resulting pulses of secondary ions are accelerated by an electric field away from the sample and into the mass spectrometer analyzer. Ions with different mass/charge ratios will travel with... 

To minimize surface damage, static SIMS mass spectrometers should be as efficient as possible for detecting the total yield of secondary ions from a surface. Also, to be able to separate elemental from molecular species, and molecular species from each other, the mass resolution usually given as the mass m divided by the separable mass Am, should be very high. With this in mind, two types of mass spectrometer have been used - in early work mainly quadrupole mass filters and, more recently, time-of-flight mass spectrometers. 

Zitomer (67) was the first to describe the coupling of a thermobalance to a time-of-flight mass spectrometer and a magnetic sector mass spectrometer. This technique eliminated the practice of collecting or trapping fractions for subsequent analysis and also permitted careful control of the furnace atmosphere. One of the important features of the TG-MS system is its relatively short dead time, that is, the time between product evolution and introduction into the mass spectrometer ion source. Under proper flow conditions, this time is of the order of seconds. There is also less probability of the formation of secondary reaction that can lead to products other than those initially evolved. 

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