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Bruker-Franzen Analytik Gmbh

Bruker Analytische Messtechnik Gmbh

Edward W Schlag

Ulrich Boesl

Jurgen Grotemeyer

Heinrich Selzle

Klaus Walter

Rudiger Frey

Hanns Von Weyssenhoff

Josef Lindner

Ronald C Beavis

Rainer Weinkauf

Hans J Neusser

When vaporizing a sample substance consisting of big molecules, in particular for the purpose of mass-spectroscopic examinations, the energy introduced for the vaporization process may lead to thermolytic decomposition of the sample substance. In order to prevent such decomposition, the invention proposes that the sample substance be mixed, prior to its irradiation, with a matrix material which is easily decomposed under the influence of the laser beam pulses. The matrix may consist of a material which absorbs the radiation and which is easily decomposed thermolytically, or else of a material which is permeable to laser radiation, but mixed with a metal powder. When the mixture is exposed to laser beam pulses, the instable matrix material will decompose first whereby the embedded molecules of the sample substance are set free. It is possible in this manner to prevent, practically completely, the molecules of the sample substance from being destructed. Suitable compounds for use as matrix material are, in particular, sugar, cellulose and NH.sub.4 NO.sub.3 as well as polyethylene, with an admixture of gold or silver powder.

Method of vaporizing a sample substance

In an MS-MS time-of-flight mass spectrometer, a space focus of the ion source is defined by correction of the second order. If the geometrical and electric values of the ion source are suitably selected, the space focus may be such as to permit very good primary mass resolution when suitable secondary interaction methods are used. The secondary interaction at the space focus may be effected (a) by a focused, pulsed laser ray or other pulsed interaction methods that can be focused. (b) by a wire mesh consisting of very fine 'line combs' engaging each other, to which voltage pulses can be applied, (c) by a combination of a) and/or b) with an electrostatically high, primary, fieldless drift path. The MS-MS time-of-flight mass spectrometer is operated using a reflector comprising a movable reflector end plate with adjustable potential, which enables primary ions to be eliminated from the spectrum without any loss in mass resolution. By tuning the reflector fields in a suitable manner, and suitable selection of an observation window in the time-of-flight spectrum, it is possible to measure a secondary mass spectrum generated at the space focus.

MS-MS time-of-flight mass spectrometer

The ion reflector of the time of flight mass spectrometer comprises between the decelerating electrodes (27, 28) defining the decelerating field and the reflector electrode (29) an additional focusing electrode (30). Just as the focusing electrode (30), the deceleration electrodes (28, 28) are also preferably designed as grid-less diaphragm rings. Further, the front decelerating electrode arranged at the input of the ion reflector has preferably a larger aperture diameter than the rear decelerating electrode (28). The arrangement of the decelerating and focusing electrodes and the potentials applied to them are selected to ensure that an inhomogenous electric field is generated in the area of these electrodes which has the effect of a lens and which in conjunction with the following homogenous field which extends to the reflector electrode (29) ensures not only focusing in time, but also perfect geometrical focusing of the ion beam upon the detector.

Time of flight mass spectrometer using an ion reflector

Method and device for producing molecular beams

A process for determining molecular spectra in unseparated mixtures, in particular unseparated isotopic mixtures, which comprises allowing said mixture to successively flow through a photoreactor which is irradiated by an adjustable-wavelength laser and then through a mass spectrometer wherein the concentration of particles of specified mass is determined by variation of the wavelength of the laser or variation of the mass setting of the mass spectrometer in such a manner that a two-dimensional spectrum results having the parameters of wavelength and mass.

Process and apparatus for determining molecule spectra

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Munchen, Germany

Edward W Schlag