Spatially correlated dynamic focusing

Patent metadata

Field	Value
Publication number	US-9406494-B2
Application number	US-201414772439-A
Country	US
Kind code	B2
Filing date	Mar 5, 2014
Priority date	Mar 5, 2013
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

A Time of Flight mass analyzer is disclosed comprising one or more acceleration electrodes and a first device arranged and adapted to apply a DC voltage pulse to the one or more acceleration electrodes. The DC voltage pulse causes ions to be accelerated into a time of flight or drift region and the DC voltage pulse is applied, in use, to the one or more acceleration electrodes between a time T 1 and a time T 2 . A second device is arranged and adapted to apply a single phase oscillating voltage to the one or more acceleration electrodes, wherein the single phase oscillating voltage undergoes multiple oscillations between the time T 1 and the time T 2 . The application of the DC voltage pulse and the single phase oscillating voltage to the one or more acceleration electrodes establishes an homogeneous electric field having a net force towards the time of flight or drift region.

First claim

The invention claimed is:

1. A Time of Flight mass analyser comprising:
one or more acceleration electrodes; and
a first device arranged and adapted to apply a DC voltage pulse to said one or more acceleration electrodes, wherein said DC voltage pulse causes ions to be accelerated into a time of flight or drift region and wherein said DC voltage pulse is applied, in use, to said one or more acceleration electrodes between a time T 1 and a time T 2 ;
wherein said Time of Flight mass analyser further comprises:
a second device arranged and adapted to apply a single phase oscillating voltage to said one or more acceleration electrodes, wherein said single phase oscillating voltage undergoes multiple oscillations between said time T 1 and said time T 2 ; and
wherein the application of said DC voltage pulse and said single phase oscillating voltage to said one or more acceleration electrodes establishes a substantially homogeneous electric field having a net force towards said time of flight or drift region.

2. A Time of Flight mass analyser as claimed in claim 1 , wherein said oscillating voltage comprises a sinusoidal, sawtooth or triangular waveform.

3. A Time of Flight mass analyser as claimed in claim 1 , wherein said first device is arranged and adapted to apply said DC voltage pulse to said one or more acceleration electrodes at substantially the same time as said second device applies said oscillating voltage to said one or more acceleration electrodes.

4. A Time of Flight mass analyser as claimed in claim 1 , wherein said oscillating voltage causes ions to experience an electric field that provides a spatially correlated energy deviation so as to reduce second or higher order spatial focusing aberrations.

5. A Time of Flight mass analyser as claimed in claim 1 , wherein said Time of Flight mass analyser comprises an orthogonal acceleration Time of Flight mass analyser.

6. A Time of Flight mass analyser as claimed in claim 1 , wherein said one or more acceleration electrodes comprise one or more orthogonal acceleration electrodes for orthogonally accelerating ions into a time of flight or drift region.

7. A Time of Flight mass analyser as claimed in claim 1 , wherein said single phase oscillating voltage has a frequency selected from the group consisting of: (i) <100 kHz; (ii) 100-500 kHz; (iii) 500-1000 kHz; (iv) 1-5 MHz; (v) 5-10 MHz; (vi) 10-50 MHz; (vii) 50-100 MHz; (viii) 100-500 MHz; (ix) 500-1000 MHz; (x) 1-5 GHz; (xi) 5-10 GHz; and (xii) >10 GHz.

8. A mass spectrometer comprising a Time of Flight mass analyser as claimed in claim 1 .

9. A method of analysing ions comprising:
providing one or more acceleration electrodes; and
applying a DC voltage pulse to said one or more acceleration electrodes between a time T 1 and a time T 2 so as to cause ions to be accelerated into a time of flight or drift region;
wherein said method further comprises:
applying a single phase oscillating voltage to said one or more acceleration electrodes, wherein said single phase oscillating voltage undergoes multiple oscillations between said time T 1 and said time T 2 and wherein the application of said DC voltage pulse and said single phase oscillating voltage to said one or more acceleration electrodes establishes a substantially homogeneous electric field having a net force towards said time of flight or drift region.

10. A method of mass spectrometry comprising a method as claimed in claim 9 .

11. A Time of Flight mass analyser comprising:
one or more orthogonal acceleration electrodes;
a drift or time of flight region arranged downstream of said one or more orthogonal acceleration electrodes;
one or more electrodes arranged in said drift or time of flight region; and
a device arranged and adapted to apply an oscillating voltage to said one or more electrodes arranged in said drift or time of flight region in order to reduce second or higher order spatial focusing aberrations.

12. A method of analysing ions comprising:
providing one or more orthogonal acceleration electrodes, a drift or time of flight region arranged downstream of said one or more orthogonal acceleration electrodes and one or more electrodes arranged in said drift or time of flight region; and
applying an oscillating voltage to said one or more electrodes arranged in said drift or time of flight region in order to reduce second or higher order spatial focusing aberrations.

Assignees

• Micromass Ltd

Inventors

• Brown Jeffery Mark
• Green Martin Raymond

Classifications

• H01J49/401 Primary

  characterised by orthogonal acceleration, e.g. focusing or selecting the ions, pusher electrode · CPC title

• H01J49/403 Primary

  characterised by the acceleration optics and/or the extraction fields · CPC title

• H01J49/0031

  Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence) · CPC title