Velocity corrected ion extraction in microscope mode imaging mass spectrometry

Modifications to a commercially available linear mass spectrometer for mass‐resolved microscopy with the pixel imaging mass spectrometry (PImMS) camera

“…The post-extraction differential acceleration (PEDA) technique pioneered by Aoki and co-workers, and its extension (velocity correction) developed by Brouard and co-workers address this issue by controlling the trajectories of ablated ions from their creation rather than letting the ablation plumes expand into the vacuum. [47,48] The pulsed focussing then occurs further along the time-of-flight path. This can extend the range at which the peak width, Δm 50 % < 1 m/z unit.…”

Microscope imaging mass spectrometry with a reflectron

“…The focused m/z can be changed by adjusting the potentials applied to each electrode using the ratio (m/z) 2 /(m/z) 1 , where (m/z) 1 is the initially optimized ion and (m/z) 2 is the ion to be focused. 37 Higher potentials, therefore, focus ions with larger m/z, and vice versa. Figure 2(a) presents the laser desorption ionization mass spectrum of Rhodamine B, optimized for its most intense peak at 343 Da and averaged over 2000 laser shots.…”

“…The mass resolved window can be tuned to focus different m/z by applying a linear scaling parameter to each electrode in the ion microscope. 37 For a fixed reflectron potential, increasing the PEDA voltage results in faster ions and a longer distance between the first temporal focus and reflectron entrance. This moves the corresponding focal plane nearer to the reflectron exit, and vice versa.…”

Account: An Introduction to Velocity-Map Imaging Mass Spectrometry (VMImMS)

“…It has recently been shown that mass resolutions of several thousand are possible in combination with imaging when employing various pulsed extraction schemes. 61,62 An important factor influencing the achievable mass resolution is the extent of the ionisation region along the ToF axis. When laser ionisation methods are used, it is straightforward to focus the laser down to a spot size of a few hundred microns.…”