Laser ablation and ionization combined with mass spectrometry (MS) forms the basis of one of the most widely exploited analytical tools of the solid state. This paper describes the first demonstration of three dimensional (3D) molecular composition imaging with nanoscale spatial resolution by extreme ultraviolet (EUV) laser ablation time of flight (TOF) MS. The key innovation of our approach is the use of a compact capillary discharge EUV laser developed at Colorado State University that emits ~10 uJ nanosecond light pulses at a wavelength of 46.9 nm. The use of the EUV laser light makes it possible to ablate craters with diameters as small as 120 nm and a depth of 3.5 nm. Moreover, the single shot ablation of organic materials produces craters with none or little sign of thermal damage to the surroundings of the focal spot. Both positive and negative ion extraction modes provide single shot detection of intact analyte molecules from probing volumes down to 50 zL. We have applied EUV TOF MS to the chemical analysis of antibiotics, aminoacids, organic dyes, and dielectrics. The corresponding mass spectra show protonation is the dominant ionization mechanism in positive extraction mode while electron attachment is predominant in negative mode. The high sensitivity and spatial resolution of EUV TOF MS has enabled the demonstration of composition imaging in organic samples with nanoscale lateral - 75 nm and depth - 20 nm resolutions, without compromising mass resolution. EUV TOF MSI is specifically suited in analysis and imaging of insoluble solid state compounds with low ionization efficiency in ultraviolet range, i.e. for the sudy of physical and chemical changes in polycyclic hydrocarbon (PAH) materials and their oligomers after thermal treatment or chemical derivatization. These innovative materials show great promise as efficient organic semiconductors for variety of applications in organic electronics.

Nanoscale 3D molecular imaging by extreme ultraviolet laser ablation mass spectrometry: a new analytical tool for the organic and inorganic solid state

249th National Meeting (2015)

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