Method and a mass spectrometer and uses thereof for detecting ions or subsequently-ionised neutral particles from samples

Abstract

A method is used in a time-of-flight mass spectrometer for analysis of a first pulsed ion beam, the ions of which are disposed along the pulse direction, separated with respect to their ion masses. The ions of at least one individual predetermined ion mass or of at least one predetermined range of ion masses can be decoupled from the first pulsed ion beam, as at least one decoupled ion beam, and the first ion beam and the at least one decoupled ion beam are analyzed.

What is claimed is: 
     
         1 .- 32 . (canceled) 
     
     
         33 . Method for operating a time-of-flight mass spectrometer for analysis of a first pulsed ion beam, the ions of which are disposed in a separated manner along the pulse direction with respect to their ion masses,
 wherein   the ions of at least one individual predetermined ion mass or of at least one predetermined range of ion masses are decoupled from the first pulsed ion beam as at least one decoupled ion beam,   the intensity of at least one decoupled ion beam or the intensity of the first ion beam is attenuated after decoupling;   and the first ion beam and the at least one decoupled ion beam are analysed, said at least one decoupled ion beam being analysed separated from the first ion beam,   wherein the analysis of one, of a plurality or of all the ion beams is effected by means of single particle detection.   
     
     
         34 . Method according to  claim 33 , wherein at least one decoupled ion beam, after attenuation of the first ion beam or of the decoupled ion beam, is reunited with the first ion beam in order to form a common ion beam. 
     
     
         35 . Method according to  claim 33 , wherein the ions of the decoupled ion beam and of the first ion beam are positioned in the common ion beam, separated with respect to their masses, advantageously corresponding to their mass. 
     
     
         36 . Method according to  claim 33 , wherein the first ion beam is analysed with lower sensitivity than the decoupled ion beam which is analysed separated from the first ion beam, or the decoupled ion beam, which is analysed separated from the first ion beam, is analysed with lower sensitivity than the first ion beam. 
     
     
         37 . Method according to  claim 33 , wherein a common mass spectrum, advantageously in portions, is determined from the analysis result with respect to the first ion beam and from the analysis result with respect to the at least one decoupled ion beam. 
     
     
         38 . Method according to  claim 33 , wherein the intensity of the first ion beam is determined as a function of the ion mass, in particular for one or more specific individual masses or for one or more specific individual mass ranges and, upon exceeding a boundary value, only the ions of the relevant mass or of the relevant mass range are decoupled from the first ion beam. 
     
     
         39 . Method according to  claim 33 , wherein the intensity of the first ion beam is determined for one or more specific individual masses or for one or more specific individual mass ranges and, upon falling below a boundary value, the ions of the relevant mass or of the relevant mass range are not or are no longer decoupled from the first ion beam. 
     
     
         40 . Method according to  claim 33 , wherein, at the beginning of the analysis, the intensity of the first ion beam is determined as a function of the ion mass, in particular for one or more specific individual masses or for one or more specific individual mass ranges and, upon exceeding a boundary value, the ions of the relevant mass or of the relevant mass range are decoupled from the first ion beam. 
     
     
         41 . Method according to  claim 33 , wherein the intensity of the first ion beam is determined continuously or at regular and/or irregular time intervals. 
     
     
         42 . Method according to  claim 40 , wherein the boundary value is that intensity of the ion beam at a specific mass or in a specific mass range above which the error, when counting single particles of the relevant mass or of the relevant mass range, exceeds a predetermined error boundary value. 
     
     
         43 . Method according to  claim 33 , wherein, wherein the analysis of one, of a plurality or of all the ion beams is effected by means of time-to-digital converters (TDC converter), and/or by means of multiparticle recording, in particular by means of analogue-digital converters (ADC). 
     
     
         44 . Time-of-flight mass spectrometer for analysis of a first pulsed ion beam, the ions of which are disposed along the pulse direction, separated with respect to their ion masses, having a first detector for analysis of the first pulsed ion beam,
 wherein   at least one beam switch which is disposed in the beam path of the first ion beam for deflecting ions of at least one specific mass or of at least one specific mass range from the first ion beam as a decoupled ion beam, and   at least one further detector for analysis of at least one decoupled ion beam and   at least one device for the attenuation of the first ion beam or of the decoupled ion beam which is disposed in the beam path of the first ion beam or of the decoupled ion beam between the beam switch which decouples the decoupled ion beam and the respective detector,   wherein at least one, a plurality or all detectors are single particle detectors.   
     
     
         45 . Time-of-flight mass spectrometer according to  claim 42 , wherein at least one of the devices for the attenuation of the ion beam is a filter. 
     
     
         46 . Time-of-flight mass spectrometer according to  claim 42 , wherein at least one control device for controlling at least one of the beam switches as a function of the intensity of the first ion beam or of the decoupled ion beam which intensity is detected by the first detector or possibly by the further detector. 
     
     
         47 . Time-of-flight mass spectrometer wherein at least one of the control devices controls the time-of-flight mass spectrometer according to a method according to  claim 33 . 
     
     
         48 . Use of a method or of a time-of-flight mass spectrometer according to claim  1 , wherein, the pulsed ion beam being produced by means of desorption, in particular by means of field desorption (FD), by means of desorption by atomic primary ions or cluster ions (SIMS) and/or by means of laser desorption (LD), in particular matrix-assisted laser desorption (MALDI), by means of plasma ionisation (ICP), by means of electrospray ionisation (ESI), by means of electron-impact ionisation (EI), by means of chemical ionisation (CI), possibly with neutral particles desorbed under subsequent ionisation, in particular by means of plasma, electrons and/or photons.