Kinetic energy distribution measurement of laser produced ions

Laser desorption mass spectrometry of nonvolatiles under shock wave conditions

“…For this purpose we used various oligosaccharide samples to get information on the thermal stress exerted on the desorbed molecules. Oligosaccharides are known to be thermally labile-stachyose more than raffinose and sucrose-and have been used repeatedly for similar applications (7)(8)(9)(10)(11)(12)18,25). We found direct evidence for the existence of at least two different desorption modes, thermal and nonthermal, depending on laser power density and sample thickness, which may even coexist under particular conditions.…”

“…Thousands of gas chromatograph/ mass spectrometers (GC/MS) are now used daily worldwide (J). A major application is the identification of unknown compounds, which in many laboratories results in the production of hundreds of unknown mass spectra per day, making obvious the need for computerized identification systems (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). For samples representing complex mixtures, incomplete GC separation is unavoidable (17,18)•, for the resulting spectra which represent more than one component reverse searching (only requiring the peaks of the reference to be in the unknown) improves retrieval performance (4)(5)(6)(7).…”

“…But keeping in mind the above outlined situation concerning the diversity of instrumentation and sample handling, it is not to be expected that there will by the one model describing all experimental conditions. Kistemaker (7)(8)(9)(10), Rpllgen (11,12), Cotter (13)(14)(15)(16)(17), and Heresch (18) favor a thermal mode for their experimental conditions: sample on bulk substrates and irradiation with moderately focused laser beams at moderate laser power densities at the sample side. However, as is pointed out in some cases (11,18,19), thermal processes cannot explain sufficiently all observed phenomena.…”

Ion cloud manipulation using the radiofrequency-only-mode as an improvement for high mass detection in fourier transform mass spectrometry

“…Important ionization methods in chemistry, such as matrix-assisted laser desorption (MALO), electrospray ionization, and fast-atom bombardment or liquid secondary ionization mass spectrometry, can produce massive ions with kinetic energy distributions that are high compared with the normal trapping well depths of a few volts [7][8][9][10][11]. Energetic ions can be trapped in deeper wells (> 10 V), but these result in poor performance owing to larger electric field inhomogeneities.…”

Lasers and Mass Spectrometry

“…sample or substrate following a single pulse. The evidence for thermal mechanisms includes the observation of thermal kinetic energy spreads for the ions formed (63,64), ion formation by gas phase cationization between codesorbed neutral molecules and thermionically emitted alkali ions (65), and broad desorption times following the laser pulse (66,67). Figure 8 shows that the desorption of quaternary ammonium ions from tetramethylammonium chloride continues for some time (microseconds) following the laser pulse but that the desorption of these "molecular ions" is enhanced at the early stages, while decomposition is generated in a longer time frame (66).…”