Molecular beam mass spectrometry

The application of a selective pyrolysis process to the recovery of chemicals from waste PU foam is described. The reaction conditions are controlled so that target products can be collected directly from the waste stream in high yields. Molecular beam mass spectrometry is used in small-scale experiments to analyse the reaction products in real time, enabling the effects of process parameters such as temperature, catalysts and co-reagents to be quickly screened. Fixed bed and fluidised bed reactors are used to provide products for conventional chemical analysis to determine material balances and to test the concept under larger scale conditions. Results are presented for the recycling of PU foams from vehicle seats and refrigerators. 12 refs. 

Kasper, T.S. et al., Ethanol flame structure investigated by molecular beam mass spectrometry. Combust. Flame, 150,220,2007. 

There are at least three approaches to fast GC/MS (1) use of microbore columns with time-of-flight mass spectrometry (TOFMS) (2) use of low-pressure (LP)-GC/MS to aid separations at increased flow rate " and (3) use of supersonic molecular beam mass spectrometry (SMBMS) (also known as supersonic GC/MS), which can accept increased flow rates and short analytical columns."... 

Jones, R. H., Olander, D. R., Siekhaus, W. J., and Schwarz, J.A. Investigation of gas-solid reactions by modulated molecular beam mass spectrometry. J. Vac. Sci. Technol. 

Molecular beam mass spectrometry has been used to study penta-fluorides ofNb, Ta, Mo, Re, Os,Ir, Ru, Rh, Pt, Sb, and Bi (139), indicating dimeric, trimeric, and even tetrameric ions (139). Simple fragmentations of the type... 

Fig. 13.11 Low-pressure, premixed, methane-air, flat flame with a molecular-beam mass-spectrometry probe positioned above the flame [187]. Photograph is courtesy of Dr. A. Mcllroy, Sandia National Laboratiories.

Dayton, D. C., French, R. J., and Milne, T. A., Direct observation of alkali vapor release during biomass combustion and gasification. 1. application of molecular-beam mass-spectrometry to switchgrass combustion. Energy Fuels 1995, 9 (5), 855-865. 

Molecular Beam Mass Spectrometry Multi-Channel Plate... 

Molecular-Beam Mass-Spectrometry. This procedure was carried out on equipment described by Evans and Milne (H). Pyrolysis of the oils (or fractions) was performed under controlled conditions and followed in real time by a free-jet, molecular beam MS. Pyrolysis products and fragmentation ions were detected. 

A.G. Lowe, A.T. Hartlier, J. Brand, B. Atakan, and K. Kohse-Hoinghaus, In situ Temperature and Species Concentration Measurements by Laser Diagnostics and Molecular Beam Mass Spectrometry, Combustion Flame, Vol.118, 1999, pp.37-50. 

The kinetics of the decay of CIO, prepared by the reaction of Cl with OCIO or with O3, have been followed by molecular beam mass spectrometry at 298 The major reaction gives Cl + ClOO and the minor reaction Cl + OCIO. The heats of formation of CIO, OCIO, and ClOO were estimated the latter two compounds are unimportant under stratospheric conditions because they will probably be photolysed. 

Fig. 51. A RE capacitively-coupled diode with a variety of plasma diagnostics, including Langmuir probe, optical emission spectroscopy, molecular beam mass spectrometry, and ion flux/energy analysis systems. After [35).

TIME-RESOLVED MOLECULAR BEAM MASS SPECTROMETRY OF TRANSIENT COMBUSTION PHENOMENA... 

Characterization Tools for Pyrolysis Oils. It wasn t too many years ago that the only tools available to the scientist interested in pyrolysis oil composition were gas chromatography and thermogravi-metric analysis. The complexity of the pyrolysis oils demands high performance equipment, and a list of such equipment mentioned during the symposium would include proton and carbon nuclear magnetic resonance spectroscopy, free-jet molecular beam/mass spectrometry (16.25), diffuse reflectEuice Fourier transform infrared spectrometry ( ), photoelectron spectroscopy ( ), as well as procedures such as computerized multivariate analysis methods (32) - truly a display of the some of the most sophisticated analytical tools known to man, and a reflection of the difficulty of the oil composition problem. 

New characterization tools such as molecular beam mass spectrometry (5Z) help in understanding the mechanisms by which wood vapor and related compounds react over catalysts. 

The goal of the molecular-beam, mass-spectrometry (MBMS) studies of biomass pyrolysis product conversion over zeolite catalysts is to provide rapid characterization, in real time, of the fate of the complex reactants as a function of reaction parameters. This technique allows the qualitative observation of transient, reactive and high molecular weight reactants and products that might otherwise escape detection by conventional collection and analysis methods. The goal is to optimize gasoline yields from biomass, at this small scale, by evaluating a typical Mobil HZSM-5 zeolite in its ability... 

Fig. 4.5. Molecular beam mass spectrometry for kinetic studies in a discharge-flow system. A, skimmer. Dj, 2 x 2501 s" diffusion pumps. Dji, trapped 7001 s diffusion pump. H, high vacuum chamber maintained at 10 torr by Djj. Ij, ion source. P, flow tube pump. S, 0-2 mm hole in quartz thimble. Str, flow system. Schr, adjusting screws. Z, intermediate vacuum chamber maintained at 5 x 10" torr by Dj.

The most direct experimental approach to the species involved in diamond growth, molecular beam mass spectrometry of stable and reactive speeies extraeted through a 300 pm orifice in the substrate plane, was used by Hsu to investigate the HF-CVD as well as the MWP-CVD process [57,58]. The most interesting results of these measurements are as follows. 

Impressed by the information provided by Py-FIMS, another research group developed pyrolysis-molecular beam mass spectrometry (Py-MBMS) by coupling a quartz pyrolysis chamber to the inlet of a triple-quadrupole mass spectrometer. This group wished to study the organic matrix of forest soils and saw two limitations for the application of Py-FIMS to their study first, that the very small sample used in Py-FIMS might not be representative of the macro soil sample, and second, that the time required for each sample analysis by Py-FIMS was relatively long if one wished to examine and compare a large number of soil samples. 

The kinetics of the reaction CH3O2 + NO3 was studied by modulated photolysis spectroscopy [7] and later in a discharge flow reactor combined with molecular beam mass spectrometry [8]. In the latter experiment, the CD3O2 radicals were used instead of CH3O2, and their first order decay monitored in the presence of excess NO3 radicals. It was however observed that the first order decay of the methylperoxy radicals did not extrapolate to a common intercept and that the second order plot showed a large positive intercept. This is caused by the regeneration of CH3O2 radicals via reaction... 

Behrens, Jr., R., (1986), A New Simultaneous Thermogravimetry and Modulated Molecular Beam Mass spectrometry Apparatus for Quantitative Thermal Decomposition Studies , Rev. Sci. Instrum., 58, pp. 451- 461. 

ABSTRACT. We describe an apparatus by which the detonation products of an explosive can be identified and whose relative concentrations can be determined quantitatively. These measurements can be made on products that have been formed in less than one microsecond after the passage of the detonation wave. The technique is based on the rapid quenching of chemical reactions by virtue of the free expansion of the products into vacuum. Of course, products that have been formed over a longer period of time and under different pressure/temperature conditions can also be studied. Time resolved molecular-beam mass spectrometry is used, so that whether detonation occurred or not in forming the products can be determined. We describe optical techniques, principally Schlieren photographs, that also confirm detonation. We report measurements made on six standard explosives, PETN, RDX, HMX, HNS, TNT and TATB, and one research explosive, nitric oxide. For none of the standard explosives do we measure product distributions that agree with model predictions based on equilibrium assumptions. A computer model of the free expansion is described briefly and its importance to the interpretation of the data is emphasized. 

A low-pressure, rich (9=2.3), laminar, premixed propene/oxygen/argon flame doped with ferrocene was studied experimentally using molecular beam mass spectrometry (MBMS) and laser-induced fluorescence (LIF) and by numerical simulations (Tian et al., 2009). The... 

Biordi, J. Lazarra, C. Papp, J. (1974). Molecular beam mass spectrometry applied to determining the kinetics of reactions in flames. I. Empirical characterization of flame perturbation by molecular beam sampling probes. Combustion and Flame, Vol.23, No. 1, pp. 73-82, ISSN 0010-2180... 

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