Collision energy, resolution

T. P. Softley At 10 meV collision energy for the H + H2 reaction the collision energy resolution is approximately 3 meV. This is due to the translational temperature of the beam and angular divergence primarily. 

Applications The diversity of MS/MS instrumentation offers considerable opportunities for polymer/addit-ive analysis. The best geometry for a particular application depends on a number of factors, including mass resolution in the first and third stages, mass range, sensitivity, available collision energy, the type of information required, data acquisition rate, etc. Polymer science applications of MS/MS comprise ... 

Compared to the H-atom Rydberg tagging technique,65 the resolution of the present method is somewhat worse, by about a factor of two. This loss in resolution, however, is realized in general only for photodissociation studies. In a typical crossed beam experiment, the product translational energy resolution is usually limited by the energy spread of the initial collision energy rather than the detection scheme. On the other hand, the present... 

D. M. Neumark Prof. Softley, what is the kinetic-energy resolution of your ion-molecule experiment I am particularly concerned about collisions that occur while the ions are being accelerated by the pulsed field. 

Positrons exhibit resonance phenomena in collisions with some atomic and molecular targets and, as with electrons, an infinite series of resonances is expected to be associated with each degenerate excitation threshold (Mittleman, 1966). For electrons, such thresholds can only arise with hydrogenic targets, but for positrons there are also degenerate thresholds in the excitation of positronium. Several of these resonances have been identified theoretically for a few simple target systems, but they are too narrow to be observed experimentally with the presently available energy resolution of positron beams. 

The observation of resonances in a scattering experiment requires high resolution of the collision energy, which, however, is rather difficult to achieve in a conventional molecular beam machine. In a photodissociation experiment, on the other hand, the frequency of the light beam determines the collision energy in the upper state and hence the necessary energy resolution is much easier to accomplish. More crucial for the... 

The novel approaches in LC-MS-based lipidomics, such as ultra-high performance LC (UHPLC), combined with high-resolution MS methodologies allow fast and reliable analysis of various classes of lipids (33). The modem instruments, with fast duty cycles, allow acquisition of high and low collision energy data simultaneously to provide both data on precursor ions and fragmentation data for all detectable molecular ions (34). 

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