Temperature-programmed desorption mass spectrometry

Interaction of nanomaterials with native cells is an important problem in modem life science. Recent progress in mass spectrometry provides a vital tool to study this problem. Advances in applications of mass spectrometry for investigating the interaction of nanoparticles with cell membranes and biomacromolecules are based on at least two methods. The first is matrix-assisted laser desorption ionization (MALDI),1 and the second is temperature-programmed desorption mass spectrometry (TPD MS), newly developed to study the interaction of nanoparticles with a cell surface.2 ... 

V. A. Pokrovskiy. Temperature-programmed desorption mass spectrometry of biomolecules, Rapid Commun. Mass Spectrom. 9, 588-591 (1995). 

Figure 1.11. A plot of the number of catalytically produced CO2 molecules against the nuclearity of Pt clusters. The CO2 molecules produced by oxidation of CO are studied by means of temperature-programmed desorption mass spectrometry. (Reproduced with permission from reference 77.)...

FIGURE 4.11 TPD mass spectra for heated carbosil prepared by phenylethanol carbonization at a silica gel surface. (Adapted from Carbon, 37, Pokrovskiy, V.A., Leboda, R., Turov, V.V., Charmas, B., and Ryczkowski, J., Temperature programmed desorption mass spectrometry of carbonized silica surface, 1039-1047, 1999, Copyright 1999, with permission from Elsevier.)... 

Danilchenko, S.N., Pokrovskiy, V.A., Bogatyrov, V.M., Sukhodub, L.R, and SuUdo-Cleff, B. 2005. Carbonate location in bone tissue mineral by X-ray diffraction and temperature-programmed desorption mass spectrometry. Cryst. Res. Technol. 40 692-697. 

TPD-MS temperature-programmed desorption-mass spectrometry TPR temperature-programmed reduction TREF temperature rising elution fractionation... 

Concerning the activation by ethylene monomer, Liu et al. reported an extensive investigation on reduction of the hexavalent chromate by means of XPS, temperature-programmed desorption-mass spectrometry (TPD-MS) methods and found that surface chromium species might exist in three oxidation states (1) surface chromate Cr(VI)Ox,surf species, (2) surface-stabihzed trivalent Cr(III) species, and (3) surface-stabilized Cr(II) species (Liu et al., 2002). Some short alkenes including propylene and butylene as well as the reduction by-product of formaldehyde were confirmed based on TPD-MS characterizations (Liu et al., 2003). 

Elementary steps in which a bond is broken form a particularly important class of reactions in catalysis. The essence of catalytic action is often that the catalyst activates a strong bond that cannot be broken in a direct reaction, but which is effectively weakened in the interaction with the surface, as we explained in Chapter 6. To monitor a dissociation reaction we need special techniques. Temperature-programmed desorption is an excellent tool for monitoring reactions in which products desorb. However, when the reaction products remain on the surface, one needs to employ different methods such as infrared spectroscopy or secondary-ion mass spectrometry (SIMS). 

The term 1 or h indicates low or high coverage of adsorbed ethene, as inferred from ethene exposures.h TPD, temperature-programmed desorption LITD, laser-induced thermal desorption 1 FT-MS, Fourier-transform mass spectrometry SIMS, secondary-ion mass spectrometry MS, mass spectrometry T-NEXAFS, transient near-edge X-ray absorption fine structure spectroscopy RAIRS, reflection-absorption infrared spectroscopy. d Data for perdeut-erio species.1 Estimated value. 

Fig. 2.8 Experimental set-up for temperature-programmed desorption studies in ultra-high vacuum. The heat dissipated in the tantalum wires resistively heats the crystal the temperature is measured by a thermocouple which is spot-welded to the back of the crystal. Desorption of gases is followed using mass spectrometry.

Temperature-programmed desorption (or decomposition) with quantitative analysis of gas-phase products (usually by mass spectrometry) has been used to help identify the ligands bonded to a metal in a supported complex. Complications such as reaction of desorbed ligands (e.g., CO) with support groups (e.g., OH) may complicate interpretation of the data (Brenner, 1986). 

The chemical nature of the surface was analysed by Temperature Programmed Desorption followed by Mass Spectrometry (TPD-MS). The samples (0.1 g) were heated up to 1273 K in He flow at a rate of 20 K min-1. The desorbed amounts of CO2, CO, H2O and H2 were monitored. 

Dealuminated M-Y zeolites (Si/Al = 4.22 M NH4, Li, Na, K, Cs) were prepared using the dealumination method developed by Skeels and Breck and the conventional ion exchange technique. These materials were characterised by infrared spectroscopy (IR) with and without pyridine adsorption, temperature-programmed desorption (t.p.d.) of ammonia. X-ray difiracto-metry (XRD) and differential thermoanalysis (DTA). They were used for encapsulation of Mo(CO)5. Subsequent decarbonylation and ammonia decomposition was monitored by mass spectrometry (MS) as a function of temperature. The oxidation numbers of entrapped molybdenum as well as the ability for ammonia decomposition were correlated to the overall acidity of the materials. It was found that the oxidation number decreased with the overall acidity (density and/or strength of Bronsted and Lewis acidity). Reduced acidity facilitated ammonia decomposition. 

The samples, prepared as self-supporting wafers, were activated in vacuum for 1 h at 873 K (MOR and ZSM5) or for 4 h at 773 K (Y zeolites). The adsorption of thiophene at 1 mbar partial pressure and room temperature were investigated by microgravimetry and IR spectroscopy. After evacuation of the zeolites at room temperature, the temperature programmed desorption (TPD) of thiophene was carried out and followed by IR spectroscopy and mass spectrometry. 

Yates group [67] used IR spectroscopy, temperature-programmed desorption, and mass spectrometry to study Xe adsorption on purified and cut SWNTs. The nanotubes were cut by subjecting them to a mixture of sulfuric and nitric acid treatment, followed by sonication with sulfuric acid and peroxide. Infrared (IR) measurements determined the presence of carboxylic acid and quinone groups on the treated tubes. Mass spectrometry of treated tubes heated under vacuum determined the evolution of different groups from the tubes as the temperature increased (CH4, CO, H2, and CO2). 

The apparatus which has been described in detail previously (ref 2), allows both temperature programmed desorption (TFD) and temperature programmed reaction (TPRn) studies to be effected. The quantitative analysis of the gas stream eluting from the reactor was accomplished by mass spectrometry. 

Adsorption and wetting Adsorption of gases and vapors, combined with IR spectroscopy, microcalorimetry, and so forth Temperature-programmed desorption of absorbed substances (ammonia, pyridine, and so forth, coupled with mass spectrometry and IR spectroscopy Heats of adsorption, specific surface area, pore size distribution, average pore diameter, and fractal dimension Acidic functional groups, relative acid strength ... 

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