Time-of-flight mass spectrum

Figure 7. Time-of-flight mass spectra showing results of platinun cluster reactions with benzene. The lower trace is clean metal without reactant. The upper trace is with the pulsed addition of. 21 % benzene in heliun. The notation indicates the nmber of adducts on each metal cluster. The metal cluster are all two photon ionized, while the observed products are single photon ionized, hence the enhancement of the product over metal signals. Reproduced from Ref. 17.

Other pattern recognition strategies have been used for bacterial identification and data interpretation from mass spectra. Bright et al. have recently developed a software product called MUSE, capable of rapidly speciating bacteria based on matrix-assisted laser desorption ionization time-of-flight mass spectra.13 MUSE constructs a spectral database of representative microbial samples by using single point vectors to consolidate spectra of similar (not identical) microbial strains. Sample unknowns are then compared to this database and MUSE determines the best matches for identification purposes. In a... 

Arnold, R. J. Reilly, J. P. High resolution time of flight mass spectra of alkylthio-late-coated gold nanocrystals. J. Am. Chem. Soc. 1998,120,1528-1532. 

Y. Ma, Y. Lu, H. Zeng, D. Ron, W. Mo, T. A. Neubert, Characterization of phosphopeptides from protein digests using matrix assisted laser desorption/ionization time of flight mass spectra metry and nanoelectrospray quadrupole time of flight mass spectrometry, Rapid Commun. Mass Spectrom., 15, 1693 1700 (2001). 

Tobe s group also succeeded in applying the [2+2]cycloreversion process to the formation of smaller carbon cages, notably C36 [40]. Macroscopic quantities of C35 have been produced before [41, 42] and were shown to contain carbon cages that are covalently connected to form polymeric clusters of overall D6h-symmetry. In their efforts to obtain C36 from acetylenic precursors, Tobe et al. prepared cyclophynes 19 and 20 [40]. LD time-of-flight mass spectra of 19 depict a signal for the anion of cyclophyne C3(3H8, generated from 19 by four-fold... 

Fig. 2 Cf-252 fission fragment ionization time-of-flight mass spectra of Er-1, Er-2, and Er-10. Hie region between m/z 1600-10000 is shown. M designates the intact Er molecule. The data for Er-1 are taken from ref. 13 by permission of the American Society of Biochemistry and Molecular Biology.

Figure 10. Laser desorption/ionization time-of-flight mass spectra of La Li-BINOL complex in anionic (top) and cationic (bottom) modes.

Fig. 1.2. Mass-resolved momentum imaging (MRMI) technique applied to the N2+ ion produced from N2 in intense laser fields ( 3.5PW/cm2). The two-dimensional momentum map is constructed from a set of time-of-flight mass spectra recorded at different angles a between the laser polarization direction and the TOF tube...

Fig. 7.6. The time-of-flight mass spectra of the ion species recorded when ethanol molecules are irradiated with intense laser pulses. The strong peak appearing at rn/q = 18 is ascribed to the residual water molecules existing in the vacuum chamber. The linear chirp rates of the laser pulses are a 1.6 x 10 2ps2, b 0 (transform limit), and c —1.6 x 10 2ps2 [13]...

Figure 2. Time-of-flight mass spectra of iron dusters as a function of increasing deuterium partial pressure in the reactor. The upper panel shows the reference mass spectrum obtained when helium only is pulsed into the reactor. The lower curves show the effect of increasing deuterium pressure.

Figure 13. Left, dispersed emission spectra (recorded with a low resolution of the detection part) of jet-cooled monomer and self-clusters of DMAEB (XII). Right, time-of-flight mass spectra. The cluster size distribution was varied by changing the operating conditions of the pulsed nozzle. Reproduced with permission from Ref. (92a).

Fig. I. Time-of-flight mass-spectra of purified films of C o and C70 on tungsten foil, taken using the laser-desorption jet-cooling mass spectrometer. The horizontal axis is linear in time-of-flight and the corresponding (nonlinear) mass scale is indicated. The maximum sublimation cell temperatures, T, are indicated.

Figure 3. Laser-desorption time-of-flight mass spectra of molecular carbon samples, (a, left) Pure Cm and Cw samples. The ions are produced by SO mJ pulses (over a I-mm area) of 266 nm radiation. Small peaks at lower masses are due to fragmentation occurring during desorption, (b, center) Enriched samples of the larger fullerenes. (c, right) Effect of desorbing laser pulse fluence on the mass spectrum of pure samples (pulse energies indicated in pJ per pulse).

We isolated C7g, Cg2 and Cg4 by high-performance liquid chromatography (the preparation is described in detail elsewhere ). Laser-desorption time-of-flight mass spectra were obtained to confirm the purity of the isolated samples. We used an ArF (193 nm) laser as the desorption light source . Mass spectra for the samples of C78, Cg2 and Cg4 are shown as inserts to Fig. la-c. We measured C NMR spectra of the higher fuiierenes using CS2 as the solvent with Cr(C5H702)3 as a relaxant. 

FIGURE 6.9 Time-of-flight mass spectra and deconvolution results of (a) unmodified (3-LGA, (b) (3-LGA after reaction with NAPQI, (c) (3-LGA after reaction with AQQI, and (d) (3-LGA after reaction with CLZox. The mass spectra of the modified protein were obtained after online reaction of the unmodified protein with electrochemically generated reactive metabolites. (From Lohmann, W. et al., Anal. Chem., 80, 9714, 2008. With permission.)... 

Figure 6. Time-of-flight mass spectra for NjO obtained with e (citation at 401 eV (top), 405 eV (middle), and 536 eV (bottom), corresponding to the 2pjt <— 1 s trans itions involving the 1 s electrons of the terminal and central nitrogen atoms and the oxygen atom, respectively.

Schiller, J., Suss, R., Petkovic, M., Zschornig, O. and Arnold, K., Negative-ion matrix-assisted laser desorption and ionization time-of-flight mass spectra of complex phospholipids mixtures in the presence of phosphatidylcholine a cautionary note on peak assignment, Anal Biochem, 309 (2002) 311-314. 

The polymer is prepared by crosslinking p-CyD in DMSO with toluene 2,4-diisocyanate (TDI) in the presence of cholesterol as the template. In order to obtain homogeneous samples, the amount of TDI is kept small. Matrix-assisted laser desorption/ionization time-of-flight mass spectra (MALDI-TOFMS) are presented in Fig. 5.5. In the presence of the template (a), both the dimers of P-CyD (mass number (M) = 2000-3500) and its trimers (M = 4000-4500) are efficiently formed. In its absence (b), however, virtually all the products are monomeric P-CyDs (M = 1000-2000). The template enormously accelerates the bridging between two P-CyD molecules. Each of the signals in the spectra corresponds to different amount of substitution by TDI. These analyses clearly show that dimeric P-CyDs (the binding sites for choles-... 

CH4. (Reproduced with permission from Professor A. W. Castleman, Jr.) Smaller frame Time-of-flight mass spectra of carbon clusters prepared by laser vaporization of graphite. ... 

FIGURE 5. TPEPICO time-of-flight mass spectra of supersonically expanded acetylene at five photon energies. Lower right HC=CH (monomer) mass peak indicating narrow shape of translationally cold parent ions. Reproduced from Reference 28 by permission of the American Institute of Physics... 

LAMMA, or LAMMS, or LMMS (laser microprobe mass analysis or spectroscopy), is based on laser ablation. A high frequency laser beam scans the area of the sample in a minimum step size, time-of-flight mass spectra of each scan are evaluated with respect to several ion signals and transformed into two-dimensional distribution plots. 

FIGURE 47.14 Time-of-flight mass spectra of peptides prepared via tryptic digestion of bovine hemoglobin. (Reprinted with permission from Lazar, I. M., et al., Electrophoresis, 24, 3655, 2003. Copyright 2003 Elsevier B.V.) (a) Peptides separated in the CEC system with monolithic column shown in Figure 47.13, (b) unseparated... 

Christian, N. P, Arnold, R. J., and Reily, J. P, Improved Calibration of Time-of-Flight Mass Spectra by Simplex Optimization of Electrostatic Ion Calculations, Anal. Chem., 11, 3317, 2000. 

Montaudo, G., Scamporrino, E., Vitalini, D., and Mineo, P., Novel Procedure for Molecular Weight Averages Measurements of Polydisperse Polymers Directly from Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectra, Rapid Comm. Mass Spectrom., 10,1551,1996. 

Vitalini, D., Mineo, P, and Scamporrino, E., Further Application of a Procedure for Molecular Weight and Molecular Weight Distribution Measurement of Polydisperse Polymers from Their Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectra, Macromolecules, 30, 5285,1997. 

Kast J, et al. Noise filtering techniques for electrospray quadrupole time of flight mass spectra. J Am Soc Mass Spectrom 2003 14 766-776. 

S.A. (1997) On the initial velocity of ions generated by matrix-assisted laser desorption ionization and its effect on the calibration of delayed extraction time-of-flight mass spectra. J. Am. Soc. Mass Spectrom., 8, 209-217. 

Christian, N.P., Arnold, R.J., and Reilly, J.P. (2000) Improved calibration of time-of-flight mass spectra by simplex optimization of electrostatic ion calculations. Anal. Chem., 71,... 

Wieme AD, Spitaels F, Aerts M, De Bruyne K, Van Landschoot A, Vandamme P. Effects of growth medium on matrix-assisted laser desorption-ionization time of flight mass spectra a case study of acetic acid bacteria. Appl Environ Microbiol. 2014 80 1528 8, 12... 

Fig. 14 Top panel. Time-of-flight mass spectra illustrating formation of H2 adducts to ESI generated ions in a 10 K ion trap (a) the dipeptide (GlyGlyH ) and (b) the tripeptide indicated in the inset. Bottom panel. Vibrational predissociation spectrum of H2-tagged GlyGlyH (solid black line). The gray overlay in trace (c) is the previously reported IRMPD spectrum [146] of the bare ion at 300 K. Stars in top panel indicate presence of naturally occurring C isotopologues...

Time of flight mass spectra of cations obtained from sucrose... 

Fig. 7. Time-of-flight mass spectra of negative ions of C4H2N02" at 96.009 Da which is clearly separated from SO4" at 95.952 Da thanks to the mass resolution of m/Am=6900...

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