| 摘要 |
<p>A reflecting MALDI oa-TOFMS instrument is provided, having a pulsed correcting lens to reduce expansion of the ion plume desorbed from the target prior to orthogonal acceleration. The Mass Spectrometer has a MALDI Source including a target (11), upon which samples are deposited, an orthogonal accelerator (12) and a mirror (16) located to deflect ions towards the detector (17). A mask (18), is located between the MALDI Sample Target (11) and the orthogonal accelerator (12), to limit the spread of ions in the orthogonal acceleration direction in the orthogonal acceleration chamber prior to the acceleration pulse being applied. A pulsed lens (19) is included between the MALDI Sample Target (11) and the mask (18). The lens comprises a plurality of cylindrical elements located axially along a path of desorbed ions travelling from the sample target (11) to the orthogonal accelerator (12). A high voltage pulse is applied between the elements of the lens as the plume travels through the lens to produce a gradient field which acts todifferentially accelerate the ions in the plume to reduce expansion of the plume prior to entry into the orthogonal accelerator.</p> |
