United States Patent [191 [ill Patent Number: 5,726,448 Smith et al. [451 Date of Patent: Mar. 10, 1998 [54] ROTATING FIELD MASS AND VELOCITY Grosshans. Peter B. and Shields, Patrick J. Comprehensive ANALYZER theory of the fourier transform ion cyclotron resonance signal for all ion trap geometries. J. Chemical Physics. vol. r/5] Inventors: Steven Joel Smith, Alhambra; Am 94(8), Apr. 15. 1991. Chutjian, La Crescenta. both of Calif. Grosshans. Peter B., Chen. Ruidan, Limbach. PatrickA. and [73] Assignee: California Institute of Technology. Marshall. Alan G. Linear excitation and detection in Fourier Pasadena, Calif. transform ion cyclotron resonance mass spectrometry.Inter- national Journal of Mass Spectrometry and Ion Process, vol. [21] Appl. No.: 803,331 139, pp. 169-189. 1994. Guan, Shenheng, Gorshkov, Michael V.. Marshall. Alan G. [22] Filed Feb. 21, 1997 Cicularly polarized quadrature excitation for Fouria-trans- Related U.S. Application Data form ion cyclotron resonance mass spectometry. Chemical Physical Letters, vol. 198. No. 1, 2. pp. 143-148. 1992. [63] Continuation of Ser. No. 694,850,Aug. 9,1996,abandonad. Guan. Shenheng and Marshall. Alan G. Filar ion cyclotron [51] Int. C1.6 ..................................................... BOlD 59/44 resonance ion trap: Spatially multiplexed dipolar and qua- [52] U.S. CI. ............................................. 290/270; 250/295 drupolar excitation for simultaneous ion axialization and [58] Field of Search ..................................... 250/290, 291, detection. Rev. Sci. Insh., vol. 66(1). pp. 63-66, Jan. 1995. 2501292, 293. 294.295 Hatakeyama, Rikizo, Sato, Naoyuki and Sato, Noriyoshi. An efficient mass separation by using traveling waves with ion [561 References Cited cyclotron frequencies. Nuclear Instruments and Methods in U.S. PmDOCUMENTS Physics Research, vol. B70. pp. 21-25. 1992. 4,221,964 911980 Schleretb et al. ....................... 250/290 (List continued on next page.) 5,495,108 211996 Apffel, Jr. et al. ..................... 25W288 Primary Examiner-Kiet T. Nguyen FOREIGN Pp;TENT DOCUMENTS Attorney, Agent, or Firm-Michaeison & Wallace WO 95/00237 111995 WIPO. [571 ABSTRACT WO 95123018 811995 WIPO . A rotating field mass and velocity analyzer having a cell with OTHER PUBLICATIONS four walls. time dependent RF potentials that are applied to Alber, G.M. and Marshall, A.G. Fourier Transform Ion each wall. and a detector. The time dependent RF potentials Cyclotron Resonance of Highly-charged Atomic Ions. create an RF field in the cell which effectively rotates within Physica Scripta. vol. 46. pp. 598-602. 1992. the cell. An ion beam is accelerated into the cell and the Campbell. Victoria. Guan. Ziqiang, Vartanian, Victor H. and rotating RF field disperses the incident ion beam according Laude, David A. Cell Geometry Considexations for the to the mass-to-charge (de) ratio and velocity distribution Fourier Transform Ion Cyclotron Resonance Mass Spec- present in the ion beam. The ions of the beam either collide trometry Remeasurement Experiment. Anal. Chela, vol. 67, with the ion detector or deflect away from the ion detector. pp. 514-518, 1991. depending on the de,RF amplitude, and RF frequency. The Caravatti. P. and Allemann, M. The 'Infinity Cell': a new Trapper-ion Cell With Radiofrequency Covered Trapping detector counts the incident ions to determine the deand Electrodes for Fourier Transform Ion Cyclotron Resonance velocity distribution in the ion beam. Mass Spectrometry. Organic Mass Spectrometry. vol. 26, pp. 514-518.1991. 24 Claims, 7 Drawing Sheets 62 I /- /- .- 68 .. .. < ,---== 66 -=4 7811 ll t --50 -------------L-------------- ,, , 5,726,448 Page 2 (YTHER PUBLICATIONS Sugihara, Ryo and Yamanaka, Kaoru. Nonlinear Ion Cyclo- Hiroki. s., T. Abe and Murakami Y. Influence of the fringing tron Resonance in Electromagnetic Wave with Non-Uni- field length on the separated 4HelDZ peak shape of a form Amplitude. Journal of the Physical Society of Japan, high-resolution quadrupole mass spectrometer. Interna- vol. 63, No. 12.pp. 43864395, Dec. 1994. tional Journal of Mass Spectrometry and Ion Processes. vol. 136. p~.85-89. 1994. Wang, Mingda and Marshall. Alan G. Laboratory-Frame Limbach. Patrick L., Grosshans, Peter B. and Marshall, Alan and Rotating-Frame Ion Trajectories in Ion Cyclotron Reso- G. Harmonic enhancement of a detected ion cyclotron nance Mass Spectrometry. International Journal of Mass resonance signal by use of segmented detection electrodes. International Journal of Mass Spectrometry and Ion Pro- Spectrometry and Ion Processes. vol. 100, pp. 323-346, cesses, vol. 123, pp. 43-47. 1993. 1990. Marshall, Alan G. and Schweikhard. Lutz. Fourier transform ion cyclotron resonance mass spectrometry: technique Xiang, Xinzhen. Grosshans. Peter B. and Marshall, Alan G. developments. International Journal of Mass Spectrometry Image charge-induced ion cyclotron orbital frequency shift and Ion Processes, vol. 118/119, pp. 37-70, 1992. for orthohombic and cylindrical FT-ICR ion traps. Interna- Marto, Jarrod A., Marshall. Alan G. and Schweikhard. Lutz. tional Journal of Mass Spectrometry and Ion Processes. vol. A hvo-electrode ion trap for Fourier transform ion cyclotron 125. pp. 33-43, 1993. resonance mass spectrometry. International Journal of Mass Spectrometry and Ion Processes, vol. 137, pp. 9-30. 1994. Fuerstenau. Stephen D. and Benner. Hemy W. Mollecular Nikolaev, E.N.. Frankevich. V.E. and Aberth. W. The reso- Weight Determination of Magadalton DNA Electrospray lution obtained from low energy ion scattering using an ion cyclotron resonance spectrometer. International Journal of Ions Using Charge Detection TimsQf-might Mass Spec- Mass Spectrometry and Ion Processes. vol. 130. pp. 9-14. trometry. Rapid Communication in Mass Spectrometry. vol. 1994. 9, pp. 11528-11538, 1995. t U.S. Patent Mar. 10, 1998 Sheet 1 of 7 5,726,448 n cq 4 U ro In c\l M 0t U.S. Patent Mar. 10, 1998 Sheet 2 of 7 5,726,448 1 +x C C US. Patent Mar. 10, 1998 Sheet 3 of 7 5,726,448 Qo t x In I w \ (& (v 10- (N US. Patent Mar. 10,1998 Sheet 4 of 7 5,726,448 co N c3 d *A v1 mN u m U 0 0-f 8) n / I us. Patent Mar. 10, 1998 Sheet 5 of 7 5,726,448 x POSITIONS X :I2 n \ 10.25n 1 \ e v,'.A e - I -6 xo GJ2 4; I 6 I -.I -.I 0 0.57~ 7T 1.5n 2n FIG. 7A 6 -- y POSrrlONS uto=0,2m/- t 4 -- 2 -- Y 0 -- hY -2 -- -4 -- -6 -- O.5n n 1.5n 2n FIG. 7B UaSa Patent Mar. 10, 1998 Sheet 6 of 7 5,726,448 0* c- U.S. Patent Mar. 10, 1998 Sheet 7 of 7 5,726,448 0 *0 00 ++0 5.726.448 1 2 ROTATING FIELD MASS AND VELOCITY For a quadrupole, the ultimate mass resolution depends on ANALYZER the accurate placement of apertures 34. the accurate posi- tioning and shaping of the rods 14. 16. 18, 20 and the This is a continuation of application Ser. No. 08/694,850, magnitude of an accurate and stable RF/DC voltage ratio. filed Aug. 9. 19%. now abandoned. 5 However, many current mass spectrometers are not ame- nable to the next generation of millimeter and sub- OlUGIN OF THE INVENTION millimeter-sized spectrometers. Such miniaturized and The invention described herein was made in the perfor- micromachined instruments are needed in the domestic mance of work under a NASA contract, and is subject to the sector for use in pollution monitoring in factories, homes, provisions of Public Law 96-517 (35 USC 202) in which the 10 auto exhausts. etc.; in laboratories for residual gas analysis Contractor has elected to retain title. and plasma processing; and on spacecraft for low-mass, low-power investigations of planetary environments. Cur- BACKGROUND OF THE INVENTION rent spectrometers either utilize magnetic fields (magnetic 1. Field of the Invention sector analyzers) and require bulky magnets and shielding; The present invention relates to mass spectrometers. and l5 Or require the Precise (0.1% tolerances) machining and in particular to a mass and velocity analyzer utilizing a Placement Of rods (quadrupole analyzer). As the size of rotating radio frequency (w)field for identifying mass and devices decreases, the manufacturing precision required can velocity distributions in ion beams. approach the micron- and submicron level, which presents 2. Related Art a formidable manufacturing challenge. Atoms and molecules present in a sampleare converted 2o Therefore, what is needed is a mass or velocity analyzer into ionsand introduced intoa mass spectrometerwhere the which is amenable to miniaturization to submillimeter ionic species are separated according to thekmass-to-charge dimensions. Such a should also be capable of (de)ratio. A chqed-p&cle detector located at the exit of respectable ion mass resolution without requh- the llliiss spectrometer counts the separated ionsin orbrto ing 0.1% dimensional tolerances. such as required in the Of identify the mass and velocity distribution in the ion beam. 25 the quadrupole mass spectrometer. In situations where the ion velocity or energy distribution of SUMMmY OF THE INVENTION a collection of ions are well known (or constant), the device provides a novel and mean of obtaining a mass TO overcome the limitations in the prior art described spectrum measurement. Information useful in detdning above. and to overcome other limitations that will become the chemical cowsition of the sample an det-ed 30 apparent upon reading and understanding the present onetype of mass spectrometer, the magnetic specification,the present invention is a rotating field mass analyzer, utilizes a magnetic field to mass select gen- and velocity analyzer. This invention includes a cell with from a sample.A gas, liquid, is bSt four walls, or two consecutive cells. each with two walls. via conventionalion SOUTCe into a bearn 35 orthogonally oriented. Time-dependent alternating RF of singly-charged ions. After the ions are accelerated by potentials are to each wall.