Apparatus and methods for separating electrons from ions

Claim 2

Apparatus for separating first charged particles from second charged particles of substantially higher mass, comprising means for causing said particles to move from a first region toward a second region, a pair of adjacent grid members interposed transversely to paths between said first region and said second region, and means for applying alternating voltages between said grid members at a rate sufficiently great to cause the second particles to be unaffected by the instantaneous potential of said grid members and to pass therethrough but to permit the first particles to respond to the instantaneous voltages of said grid members and to be captured thereby.

Claim 3

Apparatus in accordance with claim 1, wherein said means for causing said particles to move from said first region toward said second region comprises means for applying a drift field between said regions.

Claim 4

Apparatus in accordance with claim 1, further comprising a source of electrons for providing said first particles and a source of ions for providing said second particles.

Claim 5

Apparatus in accordance with claim 1, further comprising means for producing an output current in response to the particles which pass through said grid members.

Claim 6

Apparatus in accordance with claim 1, further comprising means for producing an output current in accordance with the particles captured by said grid members.

Claim 7

Apparatus in accordance with claim 1, wherein said means for applying alternating voltages between said grid members comprises means for applying alternating voltages at a frequency between substantially 1 and substantially 10 MHz.

Claim 8

Apparatus in accordance with claim 1, wherein said means for applying said alternating voltages comprises a source of sine waves.

Claim 9

Apparatus comprising an envelope, a pair of electrodes spaced in said envelope, a source of electrons adjacent to one of said electrodes, means for introducing a substance to be ionized by said electrons in said envelope, means for applying a drift field between said electrodes to cause said electrons and ions resulting from the ionizing to move toward the other of said electrodes, and filter means for capturing said electrons but permitting said ions to pass therethrough, said filter means comprising a pair of adjacent grid members interposed transversely to paths between said electrodes and means for applying high frequency alternating voltages between said grid mEmbers.

Claim 10

Apparatus comprising an envelope, a pair of electrodes spaced in said envelope, a source of electrons adjacent to one of said electrodes, means for introducing a substance to be ionized by said electrons in said envelope, means for applying a drift field between said electrodes to cause said electrons and ions resulting from the ionizing to move toward the other of said electrodes, and filter means for capturing said electrons but permitting said ions to pass therethrough, said filter means comprising a pair of adjacent grid members interposed transversely to paths between said electrodes and means for applying high frequency alternating voltages between said grid mEmbers.

Claim 11

Apparatus in accordance with claim 8, wherein said means for applying said alternating voltages to said grid members comprises means for applying sine waves to said grid members.

Claim 12

Apparatus in accordance with claim 8, wherein said grid members are interdigitated.

Claim 13

Apparatus in accordance with claim 8, wherein said means for applying said alternating voltages to said grid members comprises means for applying square waves to said grid members.

Claim 14

Apparatus in accordance with claim 8, wherein the frequency of said alternating voltages is between substantially 1 and substantially 10 MHz.

Claim 15

Apparatus in accordance with claim 8, further comprising means for measuring a current flowing in said other electrode as the result of ions impinging thereon.

Claim 16

Apparatus in accordance with claim 8, further comprising a pair of ion gates spaced between said filter means and said other electrode, and means for opening said ion gates sequentially.

Claim 17

Apparatus in accordance with claim 8, further comprising means for measuring the current flowing in said other electrode as the result of ions impinging thereon.

Claim 18

Apparatus in accordance with claim 8, further comprising means for measuring the current flowing in said filter means as the result of electrons captured thereby.

Claim 19

Apparatus in accordance with claim 8, wherein said means for introducing said substance in said envelope comprises means for introducing said substance at substantially atmospheric pressure.

Claim 20

Apparatus in accordance with claim 1, wherein said means for applying said alternating voltages comprises a source of square waves.

Claim 21

Apparatus in accordance with claim 1, wherein said grid members are interdigitated.

Claim 22

Apparatus in accordance with claim 1, wherein said means for causing said particles to move from said first region toward said second region comprises means for applying a DC potential between a pair of electrodes at said regions, respectively, and wherein said grid members are interposed transversely to paths between said electrodes and have means for applying a DC potential thereto intermediate the potentials of said electrodes and with respect to which said alternating voltages are applied.

Claim 23

Apparatus in accordance with claim 14, wherein the grid members of said filter means are interdigitated and wherein each of said ion gates comprises a pair of interdigitated grid members provided with means for maintaining the grid members at equal and opposite potentials with respect to an average potential and means for temporarily driving the grid members of each ion gate to the average potential.

Claim 26

A method in accordance with claim 22, wherein said second particles are formed by ion-molecule reactions, and further comprising segregating said second particles which pass through said grid members in accordance with their mobility, the foregoing steps being performed substantially at atmospheric pressure, and detecting at least some of the segregated particles.

Claim 27

A method in accordance with claim 22, wherein the segregating includes gating of at least some of said second particles from a first location to a second location in the drift field.