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Pulsed laser desorption with resonant two-photon ionization detection in supersonic beam mass spectrometry

Journal Article · · Anal. Chem.; (United States)
DOI:https://doi.org/10.1021/ac00298a007· OSTI ID:5630633
Laser desorption is used as a means of volatilizing high-melting-point or thermally labile compounds into a supersonic jet expansion. The neutral desorbed species are carried into the acceleration region of a time-of-flight mass spectrometer (TOFMS) where they are ionized by resonant two-photon ionization with an ultraviolet laser. In this soft ionization process only the molecular ion is detected in the TOFMS for several large polynuclear aromatic hydrocarbons and nonvolatiles such as adenine and cytosine. The desorption process in this work uses a shock mechanism in thick samples in which approximately a monolayer is desorbed per laser pulse so that extended repetitive desorption can be obtained for each sample. The effect of different wavelengths for producing neutral molecules without extensive ionization-fragmentation processes occurring is also investigated. In addition, the translational cooling of desorbed neutrals in the supersonic expansion is investigated based upon the ion packed width detected in the TOFMS.
Research Organization:
Univ. of Michigan, Ann Arbor
OSTI ID:
5630633
Journal Information:
Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 58:7; ISSN ANCHA
Country of Publication:
United States
Language:
English