Interference No. 104,745
The invention and the prior art
The subject matter of the interference relates to mass spectrometers and more particularly
to mass spectrometers of the MALDI (Matrix Assisted Laser Desorption Ionization) type. In
prior-art MALDI spectrometers, the sample, which includes a matrix material and an analyte
material, is located in a vacuum region, where it is irradiated by the laser. Such an arrangement
is shown, for example, in Figure 1 of the aforementioned Hillenkamp patent (BX 2075), wherein
the target material 10 is contained within the vacuum chamber of ion source 11, which is
connected to vacuum chamber 19 of the analyzer:
Bai's specification, in
describing a prior-art MALDI apparatus in which the target consists of co-precipitate of a matrix
and an analyte, explains that the laser pulse
induc[es] the accumulation of a large amount of energy in the co-precipitate
through electronic excitation or molecular vibrations of the matrix molecules.
The matrix dissipates the energy by desorption, carrying along the analyte into the
gaseous phase. During this desorption process, ions are formed by charge transfer
between the photoexcited matrix and the analyte.
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