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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 Hillenkamp2 — 1Centre 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.