US 4,542,293 AGranted

Process and apparatus for changing the energy of charged particles contained in a gaseous medium

AssigneeYale University

InventorsJohn B. Fenn, Masamichi Yamashita, Craig Whitehouse

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Abstract

A method of changing the energy of charged particles contained in a gas comprises allowing the gas to flow into a region of reduced pressure through a tube like member so that viscous forces exerted on the charged particles by the flowing gas molecules determine the kinetic energy of the charged particles. A potential gradient is maintained along the length of the tube so that the potential energy of the charged particles is changed as they pass through the tube. At the end of the tube a free jet expansion occurs so that the kinetic energy of the charged particles is no longer determined by the flowing gas, so that they can be accelerated to any desired kinetic energy by means of another potential gradient. The invention can be used to interface any high pressure ion source to a magnetic sector mass spectrometer, or to permit the operation of an electrospray ion source with an earthed inlet capillary with either a quadrupole or a magnetic sector mass spectrometer.

Claims38

Dependent claims

In a method of increasing the energy of charged particles contained in a gas, the improvement comprising:

(a) maintaining a flow of said gas containing said charged particles from a first region through a tube-like member into a second region where the pressure is maintained substantially lower than in said first region, said flow being great enough to ensure that collisions between molecules of said gas and said charged particles in said tube-like member substantially determine the kinetic energy possessed by said charged particles;
(b) providing along at least part of said tube-like member an electrical potential gradient in a direction which in the absence of said flow of gas would serve to reduce the kinetic energy of said charged particles passing along said tube-like member from said first to said second region, thereby increasing the potential energy of said charged particles;
(c) permitting a free expansion of said gas containing said charged particles at the outlet of said tube-like member into said second region, so that the kinetic energy of said charged particles is no longer determined by collisions with molecules of said gas;
and
(d) accelerating said charged particles to a desired kinetic energy by allowing them to pass through an electrical potential defining means maintained at a potential less than that existing at the outlet of said tube-like member.

2 more elements

Apparatus for increasing the energy of charged particles contained in a gas comprising:

(a) a first chamber adapted to contain a gas containing charged particles and having a conductive wall through which is fitted a tube-like member with its inlet flush with said conductive wall;
(b) a second chamber, one wall of which is formed by said conductive wall, into which said tube-like member extends, and means for maintaining the ambient pressure in said second chamber substantially below that in said first chamber;
(c) A first plate-like electrode disposed parallel to and spaced apart from said conductive wall and at least part way along said tube-like member;
(d) a second plate-like electrode spaced apart from and disposed parallel to said first plate-like electrode, disposed further from said conductive wall and having therein a slit or orifice aligned with said tube-like member through which at least some of said charged particles can pass after they leave said tube-like member;
(e) means for maintaining a first potential difference between said conductive wall and said first plate-like electrode which is at least as great as that required to increase the potential energy of said charged particles to a desired level during passage of said particles along said tube-like member from said first to said second chamber;
(f) means for maintaining a second potential difference between said first plate-like electrode and said second plate-like electrode equal to that required to accelerate said charged particles to a desired kinetic energy as they pass through said slit or orifice in said second plate-like electrode.

3 more elements

Dependencies are inferred from the claim text.