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Bonn 2000 – scientific programme

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MS: Massenspektrometrie

MS 2: Apparatives

MS 2.4: Talk

Monday, April 3, 2000, 17:15–17:30, HS VII

Piezoacoustic analysis of the desorption process in MALDI-MS — •Lalit Mohan Kukreja1,2, Christoph Menzel2, and Franz Hillenkamp21Centre for Advanced Technology, Indore, India — 2Institut für Med. Physik und Biophysik, Münster, Germany

A concept of simultaneous but independent measurements of MALDI ions in a conventional time-of-flight (TOF) analyzer and the acoustic stress waves, due to the desorption of charged and uncharged species, with a piezoelectric transducer will be presented. For the time resolved analysis of the transient stress waves MALDI samples were prepared on a PVDF transducer mounted on a lucite acoustic absorber. These targets were inserted into the TOF-MS for a simultaneous detection of acoustic and ion signals. For MALDI in the ultraviolet a nitrogen laser (λ=337 nm, τ=3 ns) and in the infrared region an Er:YAG (λ=2940 nm, τ=100 ns) or an optical parametric oscillator (λ=2940 nm, τ=5 ns) were used. While under typical UV-MALDI conditions no stress transients have been observed so far, the IR lasers generated signals with a good signal-to-noise ratio, probably due to the larger amount of material desorbed per single exposure. Signals with a few nanoseconds resolution can be assigned either to thermoelastic compression and relaxation of the sample or the recoil momentum of ablated material. The parametric dependence of the ion signal intensity and ablation stress transients on the incident laser fluence will be presented. Features and limitations of the piezoelectric transducer will be discussed.
Funding of L.M.K by the A.v.Humboldt Stiftung is greatly acknowledged.

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