Electron impact spectrometer of high sensitivity and large helium tolerance and process of characterizing gaseous atoms and molecules by the energy loss spectrum

Claim 2

The process of characterizing gaseous material, comprising the steps of: surrounding said gaseous material in a region of predetermined potential with a predetermined electrostatic potential barrier; impacting said gaseous material with electrons of predetermined total energy; collecting electrons having a predetermined relationship between their kinetic energy and the potential of said predetermined their kinetic energy and the potential of said predetermined electrostatic potential barrier to provide a current, said current characterizing said gaseous material; and measuring said current.

Claim 3

The process according to claim 1 wherein said collected electrons providing said current are related to the potential of said electrostatic potential barrier by having insufficient residual kinetic energy after colliding with said gaseous material to surmount said electrostatic potential barrier.

Claim 4

The process according to claim 1 wherein said collected electrons providing said current are related to the potential of said electrostatic potential barrier by having sufficient kinetic energy to surmount said electrostatic potential barrier and wherein said current includes electrons having sufficient residual kinetic energy after colliding with said gaseous material to surmount said electrostatic potential barrier.

Claim 5

The process according to claim 1 including the further step of processing said current to characterize said gaseous material.

Claim 6

The process according to claim 4 including the further step of modulating one of the potentials which establishes said predetermined electrostatic potential barrier and wherein said processing comprises the step of measuring said current as a function of said modulated potential.

Claim 7

The process according to claim 5 wherein said processing comprises the step of taking the derivative of said current with respect to said potential which is modulated.

Claim 8

The process according to claim 1 wherein said electrostatic potential barrier is varied over a predetermined range.

Claim 9

The process according to claim 1 including the further step of modulating the energy of said electrons over a predetermined energy range.

Claim 10

The process according to claim 1 wherein said electrostatic potential is provided by two potentials and wherein one of said potentials is varied in a predetermined manner with respect to the other.

Claim 11

The process according to claim 9 wherein said one potential is varied proportionally with respect to said other potential.

Claim 12

The process according to claim 9 wherein said one potential is varied to provide a constant predetermined potential difference between said one potential and said other potential.

Claim 13

The process according to claim 1 wherein said predetermined potential of said region is a substantially uniform potential.

Claim 14

The process according to claim 1 wherein said predetermined potential of said region is a varying potential.

Claim 15

The process according to claim 1 including the further step of pre-analyzing the kinetic energy distribution of said electrons impacting said gaseous material so as to impact said gaseous material with a stream of electrons having a predetermined energy distribution about a predetermined energy average.

Claim 16

The process according to claim 14 wherein said energy distribution is approximately 100 millivolts full width at half maximum.

Claim 17

The process according to claim 1 including the further step of modulating said varying retarding potential.

Claim 18

The process according to claim 16 wherein said energy distribution is approximately 100 millivolts full width at half maximum.

Claim 19

The process of characterizing gaseous material, comprising the steps of: providing a stream of electrons from an electron source at a predetermined potential; providing a collision space at a predetermined potential relative to said potential of said electron source, said predetermined relative potential being greater in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material; substantially surrounding said collision space with a variable retarding potential at a predetermined potential realtive to said potential of said electron source; evacuating the region occupied by said collsion space and said variable retarding potential to a predetermined pressure; introducing said gaseous material into said collision space; introducing said electrons into said collision space to provide said electrons with predetermined kinetic energy substantially equal in electron volts to said predetermined potential of said collision space and impacting said gaseous material with said electrons provided with said predetermined kinetic energy; varying the predetermined potential of said variable retarding potential over a predetermined potential range; providing a current by collecting electrons having insufficient residual kinetic energy after colliding with said gaseous material to surmount the potential difference between the potential of said collision space relative to said electron source and the varying potential of said variablE retarding potential relative to said electron source upon the potential diffference between said variable retarding potential and said potential of said electron source being at least less in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material; and measuring said current as a function of said varying retarding potential.

Claim 20

The process of characterizing gaseous material, comprising the steps of: providing a stream of electrons from an electron source at a predetermined potential; providing a collision space at a predetermined potential relative to said potential of said electron source, said predetermined relative potential being greater in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material; substantially surrounding said collision space with a variable retarding potential at a predetermined potential realtive to said potential of said electron source; evacuating the region occupied by said collsion space and said variable retarding potential to a predetermined pressure; introducing said gaseous material into said collision space; introducing said electrons into said collision space to provide said electrons with predetermined kinetic energy substantially equal in electron volts to said predetermined potential of said collision space and impacting said gaseous material with said electrons provided with said predetermined kinetic energy; varying the predetermined potential of said variable retarding potential over a predetermined potential range; providing a current by collecting electrons having insufficient residual kinetic energy after colliding with said gaseous material to surmount the potential difference between the potential of said collision space relative to said electron source and the varying potential of said variablE retarding potential relative to said electron source upon the potential diffference between said variable retarding potential and said potential of said electron source being at least less in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material; and measuring said current as a function of said varying retarding potential.

Claim 21

The process according to claim 16 including the further step of varying the potential of said collision space relative to said potential of said electron source to vary the kinetic energy provided said electrons over a predetermined kinetic energy range.

Claim 22

The process according to claim 19 wherein the potential of said collision space relative to said potential of said electron source is varied in a predetermined manner with respect to said varying potential of said surrounding retarding potential relative to said potential of said electron source so as to vary said kinetic energy provided said electrons in a predetermined manner with respect to said varying relative potential of said surrounding retarding potential.

Claim 23

The process according to claim 20 wherein said potential of said collision space relative to said potential of said electron source is varied proportionally with respect to said varying potential of said surrounding retarding potential with respect to said potential of said electron source so as to vary the kinetic energy provided said electrons proportionally with respect to said varying potential of said surrounding retarding potential with respect to said potential of said electron source.

Claim 24

The process according to claim 20 wherein said potential of said collision space relative to said potential of said electron source is varied to provide a predetermined constant potential difference with respect to said varying potential of said surrounding retarding potential with respect to said potential of said electron source so as to provide said electrons with varying kinetic energy in electron volts which is at a predetermined constant difference with respect to said varying potential of said surrounding retarding potential with respect to said potential of said electron source in volts.

Claim 25

The process according to claim 22 wherein said predetermined constant potential difference is at least one volt.

Claim 26

The process according to claim 22 wherein said predetermined constant potential difference is between 1 and 6 volts.

Claim 27

The process according to claim 18 wherein the potential of said collision space relative to said potential of said electron source is a predetermined relative positive potential and wherein the potential of said surrounding variable potential relative to said potential of said electron source is varied between a relative potential more positive than said relative positive potential of said collision space and a relative potential which is negative with respect to said potential of said electron source.

Claim 28

The process according to claim 18 wherein said step of measuring said current as a function of said varying retarding potential comprises the step of taking the derivative of said current with respect to said varying retarding potential.

Claim 29

The process according to claim 18 including the further step of pre-analyzing the kinetic energy distribution of said electrons from said electron source to provide a stream of electrons for impacting said gaseous material having a predetermined energy distribution about a predetermined average.

Claim 30

The process according to claim 27 including the further step of modulating the energy of said stream of electrons.

Claim 31

The process of characterizing gaseous material, comprising the steps of: providing a source of electrons, each of said electrons from said source having approximately the same energy; providing a first region of space over which the potential energy of an electron relative to the reference zero of potential energy, which referEnce zero of potential energy is defined as that potential energy for electrons at which the average energy electron from said electron source would possess zero kinetic energy, is substantially negative over a substantial portion thereof, said first region of space containing said gaseous material; providing a second region of space surrounding said first region of space and over which second region of space the potential energy of electrons increases with separation from said first region of space; bounding said second region of space with a surface at a predetermined variable potential relative to said reference zero of potential, upon said electrons from said source being introduced into said first region of space and impacting said gaseous material, certain of said electrons passing through said surface and providing a current depending in magnitude upon said predetermined variable potential, said dependence characterizing said gaseous material directing electrons from said source into said first region; and measuring said current as a function of said variable potential.

Claim 32

The process of characterizing gaseous material, comprising the steps of: providing a source of electrons, each of said electrons from said source having approximately the same energy; providing a first region of space over which the potential energy of an electron relative to the reference zero of potential energy, which referEnce zero of potential energy is defined as that potential energy for electrons at which the average energy electron from said electron source would possess zero kinetic energy, is substantially negative over a substantial portion thereof, said first region of space containing said gaseous material; providing a second region of space surrounding said first region of space and over which second region of space the potential energy of electrons increases with separation from said first region of space; bounding said second region of space with a surface at a predetermined variable potential relative to said reference zero of potential, upon said electrons from said source being introduced into said first region of space and impacting said gaseous material, certain of said electrons passing through said surface and providing a current depending in magnitude upon said predetermined variable potential, said dependence characterizing said gaseous material directing electrons from said source into said first region; and measuring said current as a function of said variable potential.

Claim 33

Apparatus for characterizing gaseous material, comprising: means for providing a stream of electrons; means for surrounding said gaseous material with an electrostatic potential at a predetermined potential, for providing said electrons with predetermined kinetic energy and for impacting said gaseous material with electrons provided with predetermined kinetic energy; and means for measuring current provided by electrons having a predetermined relationship between their kinetic energy and said predetermined potential of said electrostatic potential, said current characterizing said gaseous material.

Claim 34

Apparatus for characterizing gaseous material, comprising: means for providing a stream of electrons; means for surrounding said gaseous material with an electrostatic potential at a predetermined potential, for providing said electrons with predetermined kinetic energy and for impacting said gaseous material with electrons provided with predetermined kinetic energy; and means for measuring current provided by electrons having a predetermined relationship between their kinetic energy and said predetermined potential of said electrostatic potential, said current characterizing said gaseous material.

Claim 35

Apparatus according to claim 30 wherein said current measuring means is for measuring current provided by electrons that are related to said predetermined potential of said electrostatic potential by having insufficient residual kinetic energy after colliding with said gaseous material to surmount said electrostatic potential.

Claim 36

Apparatus according to claim 30 wherein said current measuring means is for measuring current provided by electrons that are related to said predetermined potential of said electrostatic potential by having sufficient kinetic energy to surmount said electrostatic potential and wherein said measured electrons include electrons having sufficient residual kinetic energy after colliding with said gaseous material to surmount said electrostatic potential.

Claim 37

Apparatus according to claim 30 wherein said current measuring means comprises means for measuring said current as a function of said predetermined electrostatic potential.

Claim 38

Apparatus according to claim 30 wherein said current measuring means comprises means for taking the derivative of said current with respect to said predetermined electrostatic potential.

Claim 39

Apparatus according to claim 30 further including means for varying said electrostatic potential over a predetermined range.

Claim 40

Apparatus according to claim 35 further including means for varying said kinetic energy provided said electrons over a predetermined kinetic energy range.

Claim 41

Apparatus according to claim 36 wherein said means for measuring said electron current to said grid means measure said electron current as a function of said varying potential of said electrode means, said function characterizing said gaseous material.

Claim 42

Apparatus according to claim 36 wherein said means for providing said electrons with varying kinetic energy provides said electrons with kinetic energy which is varied in a predetermined manner with respect to said varying electrostatic potential.

Claim 43

Apparatus according to claim 38 wherein said means for varying said kinetic energy provided said electrons varies said kinetic energy to provide a constant predetermined potential difference between said varying kinetic energy and said varying electrostatic potential.

Claim 44

Apparatus according to claim 38 wherein said mEans for measuring said electron current as a function of said varying potential of said electrode means is for taking the derivative of said electron current with respect to said varying potential of said electrode means.

Claim 45

Apparatus according to claim 38 wherein said means for varying said kinetic energy provided said electrons varies said kinetic energy proportionally with respect to said varying electrostatic potential.

Claim 46

Apparatus according to claim 41 wherein said derivative is the second derivative of said electron current with respect to said varying electrode means potential.

Claim 47

Apparatus according to claim 41 wherein said derivative is the third derivative of said electron current with respect to said varying potential of said electrode means.

Claim 48

Apparatus for characterizing gaseous material, comprising the steps of: means for providing a stream of electrons from an electron source at a predetermined potential; means for providing a collision space at a predetermined substantially uniform, potential relative to said potential of said electron source, said predetermined relative potential being greater in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material, and said collision space containing said gaseous material; means for introducing said electrons into said collision space to impact said gaseous material; means for substantially surrounding said collision space with a variable retarding potential at a predetermined variable potential relative to said potential of said electron source and for varying said surrounding predetermined retarding potential over a predetermined potential range; means for evacuating the region occupied by said collision space and said variable retarding potential to a predetermined pressure; upon said electrons being introduced into said collision space, said electrons acquiring predetermined kinetic energy substantially equal in electron volts to said relative predetermined potential in volts of said collision space whereby said gaseous material is impacted with said electrons of said predetermined kinetic energy; said means for providing said collision space also for collecting electrons having insufficient residual kinetic energy after colliding with said gaseous material to surmount the potential difference between said predetermined potential of said collision space relative to said electron source and the varying potential of said variable surrounding retarding potential relative to said electron source upon the potential difference between said variable surrounding retarding potential and said potential of said electron source being at least less in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material, said collected electrons providing a current; and means for measuring said current as a function of said varying surrounding retarding potential.

Claim 49

Apparatus for characterizing gaseous material, comprising the steps of: means for providing a stream of electrons from an electron source at a predetermined potential; means for providing a collision space at a predetermined substantially uniform, potential relative to said potential of said electron source, said predetermined relative potential being greater in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material, and said collision space containing said gaseous material; means for introducing said electrons into said collision space to impact said gaseous material; means for substantially surrounding said collision space with a variable retarding potential at a predetermined variable potential relative to said potential of said electron source and for varying said surrounding predetermined retarding potential over a predetermined potential range; means for evacuating the region occupied by said collision space and said variable retarding potential to a predetermined pressure; upon said electrons being introduced into said collision space, said electrons acquiring predetermined kinetic energy substantially equal in electron volts to said relative predetermined potential in volts of said collision space whereby said gaseous material is impacted with said electrons of said predetermined kinetic energy; said means for providing said collision space also for collecting electrons having insufficient residual kinetic energy after colliding with said gaseous material to surmount the potential difference between said predetermined potential of said collision space relative to said electron source and the varying potential of said variable surrounding retarding potential relative to said electron source upon the potential difference between said variable surrounding retarding potential and said potential of said electron source being at least less in volts than the kinetic energy lost by said electrons in electron volts upon said electrons colliding with said gaseous material, said collected electrons providing a current; and means for measuring said current as a function of said varying surrounding retarding potential.

Claim 50

Apparatus according to claim 44 wherein the potential of said collision space relative to said potential of said electron source is a predetermined relative positive potential and wherein the potential of said surrounding variable potential relative to said potential of said electron source is varied between a relative potential more positive than said relative positive potential of said collision space and a relative potential which is negative with respect to said potential of said electron source.

Claim 51

Apparatus according to claim 44 wherein said means for mmeasuring said current as a function of said varying retarding potential comprises means for taking the derivative of said current with respect to said varying retarding potential.

Claim 52

Apparatus according to claim 44 further including means for modulating said variable retarding potential.

Claim 53

Apparatus according to claim 44 further including means for pre-analyzing the kinetic energy distribution of said electronS so as to impact said gaseous material with a stream of electrons having a predetermined energy distribution about a predetermined energy means.

Claim 54

Apparatus according to claim 48 wherein said energy distribution is approximately 100 millivolts full width at half minimum.

Claim 55

Apparatus according to claim 44 further including means for varying the potential of said collision space relative to said potential of said electron source to vary the kinetic energy provided said electrons over a predetermined kinetic energy range.

Claim 56

Apparatus according to claim 50 wherein said means for varying the potential of said collision space relative to said potential of said electron source is for varying such potential in a predetermined manner so as to vary said kinetic energy provided said electrons in a predetermined manner with respect to said varying relative potential of said surrounding retarding potential.

Claim 57

Apparatus according to claim 51 wherein said means for varying the potential of said collision space relative to said potential of said electron source is for varying such potential proportionally with respect to said varying potential of said surrounding retarding potential with respect to said potential of said electron source so as to vary the kinetic energy provided said electrons proportionally with respect to said varying potential of said surrounding retarding potential with respect to said potential of said electron source.

Claim 58

Apparatus according to claim 51 wherein said means for carrying the potential of said collision space relative to said potential of said electron source is for varying such potential so as to provide a predetermined constant potential difference between such potential and said varying potential of said surrounding retarding potential with respect to said potential of said electron source so as to provide said electrons with varying kinetic energy in electron volts which is at a predetermined constant difference with respect to said varying potential in volts of said surrounding retarding potential with respect to said potential of said electron source.

Claim 59

Apparatus for characterizing gaseous material, comprising: means for providing a stream of electrons; means for selecting a substream of said stream of electrons having a narrower energy spread than that of said stream of electrons; grid means for establishing a region of positive potential, said region containing gaseous material to be characterized, and said grid means having a predetermined percentage of transmission for electrons; electrode means surrounding said grid means, said electrode means for establishing a retarding field region and for accepting an electron current; means for providing said electrode means with a varying potential; means for introducing said substream of electrons into said region of positive potential to impact gaseous material received therein; and means for measuring the electron current to said grid means as a function of the potential of said electrode means, said current characterizing said gaseous material.

Claim 60

Apparatus for characterizing gaseous material, comprising: means for providing a stream of electrons; means for selecting a substream of said stream of electrons having a narrower energy spread than that of said stream of electrons; grid means for establishing a region of positive potential, said region containing gaseous material to be characterized, and said grid means having a predetermined percentage of transmission for electrons; electrode means surrounding said grid means, said electrode means for establishing a retarding field region and for accepting an electron current; means for providing said electrode means with a varying potential; means for introducing said substream of electrons into said region of positive potential to impact gaseous material received therein; and means for measuring the electron current to said grid means as a function of the potential of said electrode means, said current characterizing said gaseous material.

Claim 61

Apparatus for characterizing gaseous material, comprising: means providing a source of electrons, each of said electrons from said source having approximately the same energy; means providing a first region of space over which the potential energy of an electron relative to the reference zero of potential energy, which reference zero of potential energy is defined as that potential energy for electrons at which the average energy electron from said electron source would possess zero kinetic energy, is substantially negative over a substantial portion thereof, said first region of space containing said gaseous material; means providing a second region of space surrounding said first region of space and over which second region of space the potential energy of electrons increases with separation from said first region of space; means providing a surface at a predetermiNed variable potential relative to said reference zero of potential and which surface bounds said second region of space, upon said electrons from said source being introduced into said first region of space and impacting said gaseous material, certain of said electrons passing through said surface and providing a current depending in magnitude upon said predetermined variable potential, said dependence characterizing said gaseous material means for directing electrons from said source into said first region; and means for measuring said current as a function of said variable potential.

Claim 62

Apparatus for characterizing gaseous material, comprising: means providing a source of electrons, each of said electrons from said source having approximately the same energy; means providing a first region of space over which the potential energy of an electron relative to the reference zero of potential energy, which reference zero of potential energy is defined as that potential energy for electrons at which the average energy electron from said electron source would possess zero kinetic energy, is substantially negative over a substantial portion thereof, said first region of space containing said gaseous material; means providing a second region of space surrounding said first region of space and over which second region of space the potential energy of electrons increases with separation from said first region of space; means providing a surface at a predetermiNed variable potential relative to said reference zero of potential and which surface bounds said second region of space, upon said electrons from said source being introduced into said first region of space and impacting said gaseous material, certain of said electrons passing through said surface and providing a current depending in magnitude upon said predetermined variable potential, said dependence characterizing said gaseous material means for directing electrons from said source into said first region; and means for measuring said current as a function of said variable potential.