| US 4,963,736 C2 (7032nd) | ||
| MASS SPECTROMETER AND METHOD AND IMPROVED ION TRANSMISSION | ||
| Donald J. Douglas, Toronto, Canada, and John B. French, Oakville, Canada, assignors to MDS Inc., Etobicoke, Ontario, Canada | ||
| Reexamination Request No. 90/008,608, Sep. 25, 2007. | ||
| Reexamination Certificate for Patent 4,963,736, issued Oct. 16, 1990, Appl. No. 437,047, Nov. 15, 1989. | ||
| Reexamination Certificate B1 4,963,736, issued May 25, 1999. | ||
| Claims priority, application Canada, Dec. 12, 1988, 585694 | ||
| Int. Cl. H01J 49/34;49/42 (2006.01) | ||
| U.S. Cl. 250—292 |
| AS A RESULT OF REEXAMINATION, IT HAS BEEN DETERMINED THAT: |
| The patentability of claims 1-30 is confirmed. |
| 1. A mass spectrometer system comprising: (a) first and second vacuum chambers separated by a wall, said first vacuum chamber having an inlet orifice therein,
(b) means for generating ions of a trace substance to be analyzed and for directing said ions through said inlet orifice into said first vacuum chamber,
(c) a first rod set in said first vacuum chamber extending along at least a substantial portion of the length of said first vacuum chamber, and a second rod set in said second vacuum chamber, each rod set comprising a plurality of elongated parallel rod means spaced laterally apart a short distance from each other to define an elongated space therebetween extending longitudinally through such rod set, said elongated spaces of said first and second rod sets being first and second spaces respectively, said first rod set being located end to end with said second rod set so that said first and second spaces are aligned,
(d) an interchamber orifice located in said wall and aligned with said first and second spaces so that ions may travel through said inlet orifice, through said first space, through said interchamber orifice, and through said second space,
(e) means for applying essentially an AC-only voltage between the rod means of said first rod set so that said first rod set may guide ions through said first space,
(f) means for applying both AC and DC voltages between the rod means of said second rod set so that said second rod set may act as a mass filter for said ions,
(g) means for flowing gas through said inlet orifice into said first space,
(h) means for pumping said gas from each of said chambers,
(i) the pressure in said second chamber being a very low pressure for operation of said second rod set as a mass filter,
(j) the product of the pressure in said first chamber times the length of said first rod set being equal to or greater than 2.25×10−2 torr cm but the pressure in said first chamber being below that pressure at which an electrical breakdown will occur between the rod means of said first rod set,
(k) and means for maintaining the kinetic energies of ions moving from said inlet orifice to said first rod set at a relatively low level, whereby to provide improved transmission of ions through said interchamber orifice.
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