Linear time of flight

Brown, R. S. Lennon, J. J. Mass resolution improvement by incorporation of pulsed ion extraction in a matrix-assisted laser desorption/ionization linear time-of-flight mass spectrometer. Anal. Chem. 1995,67,1998-2003. 

R. S. Brown and J. J. Lennon. Mass Resolution Improvement by Incorporation of Pulsed Ion Extraction in a Matrix-Assisted Laser Desorption/Ionization Linear Time-of-Flight Mass Spectrometer. Anal. Chem., 67(1995) 1998-2003. 

R. M. Whittal, L. M. Russon, S. R. Weinberger, and L. Li. Functional Wave Time-Lag Focusing Matrix-Assisted Laser Desorption/Ionization in a Linear Time-of-Flight Mass Spectrometer Improved Mass Accuracy. Anal Chem., 69(1997) 2147-2153. 

Schuerch, S. Schaer, M. Boemsen, K.O. Schlunegger, U.P. Enhanced Mass Resolution in MALDl Linear Time-of-Flight Mass Spectrometry. Biol. Mass Spectrom. 1994,25, 695-700. 

Another type of dynamic mass spectrometer is the time-of-flight (ToF) analyzer. In 1946, Stephens presented his concept of the linear time-of-flight mass spectrometer (ToF-MS) as the simplest mass separation technique at an American Physical Society meeting in Cambridge, MA.49 Cameron and Eggers first published the design and showed mass spectra for linear ToF-MS in... 

Dynamic mass separation systems use the fact that ions with different masses (accelerated with the same voltage) possess several velocities and consequently their flight times are different. There are about 50 dynamic separation systems known2 using several types of ion movements (linear straight ahead, linear periodic or circular periodic as a function of the electric or magnetic sector field applied). The simplest dynamic mass separation system is a linear time-of-flight (ToF) mass analyzer, and a widely applied mass separation system is the quadrupole analyzer. 

Figure 3.10 Diagram of a linear time-of-flight mass analyzer separation of ions is shown with three different masses (heavy ions - Of i°ns of medium mass and light ions - ). The flight time of heavy ions is longer than that of light ions due to their lower kinetic energy.

Figure 16.6—Linear time of flight (TOF) and principle of the reflectron. 1) Sample and sample holder 2) MALDI ionisation device 3 and 3 ) extraction and acceleration grid (5 000 V potential drop) 4) control grid 5) multichannel collector plate 6) electron multiplier 7) signal output. The bottom figure shows a reflectron, which is essentially an electrostatic mirror that is used to time-focus ions of the same mass, but which have different initial energies. This device increases resolution, which can attain several thousand.

Fig. 1. kHz molecular beam ablation setup with a linear time of flight mass spectrometer. 

Kemptner J (2009) Evaluation of matrix-assisted laser desorption/ionization (MALDI) preparation techniques for surface characterization of intact Fusarium spores by MALDI linear time-of-flight mass spectrometry. Rapid Commun Mass Spectrom 23 877-884. doi 10.1002/... 

Mass analyzer/ Feature Linear Quadrupole Quadrupole ion trap Linear time-of-flight Reflectron time-of-flight... 

A.E. CAMERON and D.F. EGGERS publish design and mass spectra for a linear time-of-flight (LTOF) mass spectrometer [25], W. STEPHENS proposed the concept of this analyser in 1946 [26]. 

Schematic description of a continuous extraction mode and a delayed pulsed extraction mode in an linear time-of-flight mass analyser, o = ions of a given mass with correct kinetic energy = ions of the same mass but with a kinetic energy that is too high. Delayed pulsed extraction corrects the energy dispersion of the ions leaving the source with the same mjz ratio.

Liquid Secondary Ion Mass Spectrometry Linear Time of Flight Matrix-Assisted Laser Desorption Matrix-Assisted Laser Desorption/Ionization Molecular Beam... 

Figure 9.8 Schematic of a reflectron time of flight mass analyser. Reflectron lenses act as an electrostatic mirror to both increase the effective length of the flight path, but also to compensate for ion kinetic energy variations (Uq), resulting in higher mass accuracy relative to purely linear time of flight mass analyzers. Consequently, linear time of flight analyzers are nowadays largely obsolete.

Further performance improvements in analysing nucleic acids could be achieved by the introduction of 3-hydroxypicolinic add as matrix [8] and the introduction of delayed extraction in a linear time-of-flight mass spectrometer [9]. If, for MALDI Fourier transform mass spectrometry, the molecular weight range in analysing nucleic add fragments could be extended further this type of MALDI MS would become of significant value due to the extraordinary resolution possible [10, 11]. In order to reach the sensitivity level necessary for MALDI-TOF MS analysis an amplification step has to be incorporated into the sample preparation process for... 

Mass spectrometric analysis Spectra were recorded on a Bruker Reflex 111 time-of-flight mass spectrometer (Bruker Daltonik GmbH, Bremen, Germany). This mass spectrometer was equipped with a Scout MTP ion source with delayed extraction. Spectra were recorded in positive ion linear time-of-flight mode. Typical acceleration potentials were 18 kV. For delayed extraction, the acceleration potential was switched with a delay of 200 ns. 

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