Mass spectroscopy apparatus

Temperature programmed desorption (TPD) of NH3 adsorbed on the samples was carried out on an Altamira TPD apparatus. NH3 adsorption was performed at 50°C on the sample that had been heat-treated at 120°C in a helium flow. After flushing with helium, the sample was subjected to TPD from 50 to 600°C (AT = 10°C min 1). The evolved NH3, H20 and N2 were monitored by mass spectroscopy by recording the mass signals of m/e = 16, 18 and 28, respectively using a VG Trio-1 mass spectrometer. 

Figure 1. Schematic of a typical electrospray apparatus as used in electrospray mass spectroscopy (see text for explanation of dimensions)...

Frictional Force Microscopy Fourier-transform infrared spectroscopy scanning electron microscope surface force apparatus Secondary ion mass spectroscopy scanning tunneling microscope X-ray photoelectron spectroscopy bovine serum albumin immunoglobulin G... 

Figure 5. Absorption spectroscopy by two-photon ionization mass spectrometry, apparatus (A) and schematic for a dimer (B). Substates of the intermediate electronic state are spectroscopically investigated.

Triethylarsine pyrolysis under MOCVD-type conditions was investigated by Speckman and Wendt using GC-mass spectroscopy. In studies of this type it is essential to be mindful of the apparatus employed. Accordingly the appratus is shown schematically in Figures 3 and 4. Their results are summarized in Figures 5 and 6. 

The emphasis now being placed upon the GLC/mass spectroscopy combination is already paying a rich dividend in some areas of analytical chemistry. Further research on this combination is bound to lead to a quickening interest from instrument manufacturers. The need is for an apparatus which is sufficiently sensitive and which, in terms of expense and expert labor, is within the range of laboratories specializing in residue analysis. When a reasonably inexpensive and easy-to-use equipment, capable of working at trace concentrations, becomes available, it will have the capacity to solve many analytical problems. However, it will be some years before this kind of instrument is on the market. 

The essential apparatus for pressure measurement and analysis, and other important aspects such as furnaces and temperature control, are reviewed for thermal, photochemical and radiochemical systems. The latter two also involve sources of radiation, filters and actinometry or dosimetry. There are three main analytical techniques chemical, gas chromatographic and spectroscopic. Apart from the almost obsolete method of analysis by derivative formation, the first technique is also concerned with the use of traps to indicate the presence of free radicals and provide an effective measure of their concentration. Isotopes may be used for labelling and producing an isotope effect. Easily the most important analytical technique which has a wide application is gas chromatography (both GLC and Gsc). Intrinsic problems are those concerned with types of carrier gases, detectors, columns and temperature programming, whereas sampling methods have a direct role in gas-phase kinetic studies. Identification of reactants and products have to be confirmed usually by spectroscopic methods, mainly IR and mass spectroscopy. The latter two are also used for direct analysis as may trv, visible and ESR spectroscopy, nmr spectroscopy is confined to the study of solution reactions... 

The hydrolysis of Alq3 was characterized with a gas chromatography and mass spectroscopy (GC-MS) apparatus modified with a headspace accessory designed to study volatile products evolved from solid materials (illustrated in Fig. 3.2, inset).41 Powder or film (deposited on foil) samples of Alq3 were held in a constant-temperature injection port for a given time, and the eluents at the end of the heating period were fed to the GC column. The relative areas of water and Hq peaks were used to measure the conversion (a typical trace is shown in Fig. 3.2). The prepurified Alq3 samples were allowed to absorb an equilibrium amount of water from the atmosphere, which occurred in about 3 min for the samples used.16... 

The ASTM F 1185 designation specifies chemical and crystallographic requirements for hydroxyapatite applied to the surfaces of surgical implants. Elemental analyses for calcium and phosphorus will confirm the expected stoichiometry of hydroxyapatite. The calcium and phosphorus contents will be determined by a suitable method such as ion chromatography. A quantitative X-ray diffraction analysis will determine a hydroxyapatite content of at least 95%. The concentration of deleterious trace elements such as arsenic, cadmium, mercury and lead will be assessed for hydroxyapatite derived from natural resources. The analysis of other trace elements may be required, based on the conditions, apparatus or environments specific to the manufacturing techniques and raw materials. Inductively coupled plasma/mass spectroscopy (ICP/MS), atomic absorption (AAS) or the... 

In 1979 Bickley and Vishwanathan reported that N2 was oxidized in a series of experiments in which Ti02 was irradiated under air or a nitrogen oxygen mixture of unspecified composition. A similar effect was observed when Ti02 was irradiated under pure oxygen and subsequently exposed to N2. Products were thermally desorbed and analyzed by mass spectroscopy in conjunction with GLC [122], The putative catalyst was 99% pure commercially available rutile powder with water adsorbed on its surface prior to irradiation. The surface area of the powder was determined by krypton absorption at 78 K to be 13m2g 1. The experimental apparatus was not described. 

A variety of techniques and apparatus have been developed to study and measure surface properties of pol5uners and other materials. Three of the most useful techniques for such measurements are electron spectroscopy for chemical analysis (ESCA) also known as x-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS) and ion scattering spectroscopy (ISS). Table 10.8 shows a comparison of the sampling depth of traditional methods and the new techniques. These analyses can focus on a much shallower thickness of the surface and virtually yield analyses of the outermost layers of a polymer article. Some of these methods and examples of their application to fluoroplastics are discussed below. 

Our apparatus is considered to need pulsed valves, an ultra high vacuum system and Time of flight mass spectroscopy (TOP) because of the above requirements (Fig. 2). We call our newly developed apparatus Toyota Timc-rcsoIvcd Timc-of-llighi Mass-spcctromcicr with Molecular-Pulsc-Probc Reaction Analysis at the Surface of a Catalyst (TMPRAS TM+)... 

An article on the mass-spectrometric analysis of g.l.c. effluents has been published, together with reviews on g.l.c. in combination with mass spectroscopy and with infrared spectroscopy. Although combined g.l.c.-m.s. instruments may be purchased, it is often found necessary to adapt existing apparatus. Several papers give details of such modifications for instance, constructional details for a probe to fit the AEI MS-9 have been published, a simple heated inlet system has been described, and molecule separators have been discussed. Methods for interfacing g.l.c. and m.s. instruments have been reviewed by D. I. 

Among chemical analysis methods are gas chromatography, infrared spectroscopy, and mass spectroscopy for example, a TGA apparatus may be coupled with a Fourier Transform Infrared (FTIR) spectrophotometer to measure the thermal oxidative stabilities of several fluorinated polyimides." ... 

Quantum chemistry has certainly come of age, and quantum chemical concepts appear in nearly all papers published in the chemical literature today. Actual quantum chemical calculations are now reported in many experimental papers, and computer codes that perform these calculations are now often considered as another piece of chemical apparatus. Various experimental groups now train experts in computational chemistry, along with experts in NMR spectroscopy, mass spectroscopy, and so on. Nearly all molecular electronic structure calculations today start with molecular orbital (MO) calculations, but the history of the development of this methodology is often forgotten. Today s heroes have become the writers of useful computer code, but the basic underpinnings of these codes, the ideas that let these codes develop and become useful and those who developed these ideas, are often forgotten. Who is Roothaan What did he do that so influenced MO theory I can make my distinction of theoretical chemist versus computational chemist, should such a distinction be appropriate, on the basis of this answer. This short manuscript reviews the 1951 paper by C.C.J. Roothaan entitled New developments in molecular orbital theory [1], hopefully putting this... 

The evolved gas analyses were conducted on FTIR and mass spectroscopy (MS) devices, coupled to the TG apparatus. The main volatile compounds released below 350 °C were carbon dioxide and water vapours, which increased during the whole thermal decomposition process. Alcohol traces and aromatic structured compounds were also identified. Volatile structures containing carbonyl groups were found in the gaseous mixture at temperature values above 350 °C. Ammonia evolvement was also found in the gaseous mixture. The MS spectra were in good correlation with the findings from the FTIR spectra data. 

Lee, S., Hoobler, R.J., Leone, S.R. (2000) A Pulsed Laval Nozzle Apparatus with Laser Ionization Mass Spectroscopy for Direct Measurements of Rate Coefficients at Low Temperatures with Condensable Gases. Rev. Sci. Instrum. 71 1816-1823. 

Because fluorescence detection by repeated absorption-emission cycles is not applicable to trapped molecular ions in UHV, that is, in the absence of collisions with a buffer gas [68], different techniques are required for their reliable identification. A commonly used destructive technique for molecular ions is time-of-flight (TOP) mass spectroscopy. We have used a simplified variant in the Ba+ apparatus. The trapped ions are extracted from the trap by reducing the radio-frequency amplitude, in the presence of a finite dc quadrupole potential Vo, which causes the ion trajectories to become unstable (the Mathieu -parameter enters the instability region). Heavy and hot ions escape first. Upon leaving the trap, the ions are guided to and attracted by the cathode of a channel electron multiplier (CEM) and counted. 

ATP apparatus equipped with a mass spectrometer. Right-hand side TPR patterns of silica-supported Rh, Fe, and Fe-Rh catalysts, which had been previously calcined to ensure that all metals are oxidized at the start of the measurement. [Adapted from J.W. Niemantsverdriet, Spectroscopy in Catalysis, An Introduction (2000), Wiley-VCH, Weinheim, and H.F.J. van t Blik and J.W. Niemantsverdriet, Appl. Cota/. 10 (1984) 155.]... 

The apparatuses used for the studies of both ammonia synthesis emd hydrodesulfurization were almost identical, consisting of a UHV chamber pumped by both ion and oil diffusion pumps to base pressures of 1 x10 " Torr. Each chamber was equipped with Low Energy Electron Diffraction optics used to determine the orientation of the surfaces and to ascertain that the surfaces were indeed well-ordered. The LEED optics doubled as retarding field analyzers used for Auger Electron Spectroscopy. In addition, each chamber was equipped with a UTI 100C quadrupole mass spectrometer used for analysis of background gases and for Thermal Desorption Spectroscopy studies. 

Abstract A brief introduction deals with the time period from Dalton to the discovery of isotopes by Soddy and Fajans in the early twentieth century which was soon followed by the invention of the mass spectrograph (1922). The next section covers the period from 1922 to the discovery of deuterium by Urey and his colleagues. It includes a discussion of isotope effects in spectroscopy, particularly band spectra of diatomic molecules, and also discusses the discovery of the important stable isotopes in the second row of the periodic table. It ends with the discovery of deuterium, probably the most popular isotope for isotope effect studies. The chapter ends with a short description of the apparatus of theory and experimentation available for isotope effect work at the time of the discovery of deuterium. 

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