CA1107232A
Expired / Lapsed
CA
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Use of autoionization transitions in isotopically selective photoexcitation
Assignee: Jersey Nuclear Avco Isotopes Inc
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Filing: 1978-12-18
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Granted: 1981-08-18
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Expires: 1998-12-18
Abstract
Abstract A B S T R A C T Apparatus and process for isotopically selective multi-step photoionization in which the final or ionizing step is tuned to produce a specific transition to an excited state above ionization for which the ionization cross-section is substantially greater than for ionization transitions in general. The autoionization transition to an ionized state is typically made from a highly excited bound state which is reached in one or two isotopically selective energy jumps from the ground state or other low-lying levels. The isotope shift for the ionization transition is typically small compared to the bandwidth of the ionization transition and relatively broad band photoionization radiation covering the entire absorption line can be employed. Broad band radiation is more economic and is preferable for use whereever possible. A technique is also shown for identifying the ionization transitions of augmented cross-section.
Inventors
- 👤 Robert E. Schlier
- 👤 George S. Janes
Bibliographic Details
Application Number
—
Jurisdiction
CA
Data Source
google_patents
Last Synchronized
2026-11-07 10:17
CPC Classifications
B; B01; B01D; B01D59/00; B01D59/34
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
110 words
A method for ionizing particles of a selected isotope type in an environment of plural isotope types comprising the steps of: selectively exciting the particles of said selected isotope type in one or more energy steps to an excited state; applying electromagnetic radiation of a predetermined spectral width and frequency and tuned to an absorption line for the particles in said excited state which both excites the particles from the excited state to a state within a predetermined energy range above the ionization level and excites the particles with a predetermined frequency which is absorbed more strongly than absorption at immediately adjacent frequencies by at least an order of magnitude.
Claim 2
Independent Claim
110 words
A method for ionizing particles of a selected isotope type in an environment of plural isotope types comprising the steps of: selectively exciting the particles of said selected isotope type in one or more energy steps to an excited state; applying electromagnetic radiation of a predetermined spectral width and frequency and tuned to an absorption line for the particles in said excited state which both excites the particles from the excited state to a state within a predetermined energy range above the ionization level and excites the particles with a predetermined frequency which is absorbed more strongly than absorption at immediately adjacent frequencies by at least an order of magnitude.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein the step of selectively exciting includes the step of exciting in at least three energy steps to said excited state.
Claim 4
Dependent Claim
20 words
The method of claim 1 wherein said electromagnetic radiation is tuned within a range of approximately 5,800 to 6,000 angstroms.
Claim 5
Dependent Claim
20 words
The method of claim 1 wherein said predetermined energy range is approximately 50 to 300 cm-1 above the ionization level.
Claim 6
Dependent Claim
48 words
The method of claim 1 wherein: the step of selectively exciting includes applying at least one frequency of narrow band radiation tuned selec-tively for an absorption line of said selected isotope; and said predetermined spectral width is substantially greater than the spectral width of said narrow band radia-tion.
Claim 7
Dependent Claim
20 words
The method of claim 5 wherein said predetermined spectral width is on the order of magnitude of approximately 0.5 angstroms.
Claim 8
Dependent Claim
59 words
The method of claim 1 further including the steps of: varying the frequency of said electromagnetic radiation over a range including said predetermined frequency and frequencies either side thereof which are less strongly absorbed by particles in said excited state; and detecting the degree of absorption by the particles in said excited state over the range of frequency variation.
Claim 9
Dependent Claim
11 words
The method of claim 1 wherein said particles include uranium atoms.
Claim 10
Dependent Claim
13 words
The method of claim 8 wherein the selected isotope is the U-235 isotope.
Claim 11
Dependent Claim
24 words
The method of claim 1 further including the step of separating the particles excited to said state above the ionization level from said environment.
Claim 12
Dependent Claim
16 words
The method of claim 10 wherein said separating step includes applying crossed electric and magnetic fields.
Claim 13
Dependent Claim
12 words
The method of claim 1 wherein said electromagnetic radiation includes laser radiation.
Claim 14
Dependent Claim
17 words
The method of claim 1 wherein said step of selectively exciting includes exciting in two energy steps.
Claim 15
Dependent Claim
17 words
The method of claim 1 wherein the selectively exciting step includes the step of applying laser radiation.
Claim 16
Dependent Claim
21 words
The method of claim 1 wherein the step of applying electromagnetic radiation includes producing autoionization of particles in said excited state.
Claim 17
Dependent Claim
23 words
The method of claim 15 wherein the autoionization step is generally produced without isotopic selectivity with respect to particles in said excited state.
Claim 18
Independent Claim
136 words
A method for ionizing particles of a selected isotope type in an environment of plural isotope types including the steps of: selectively exciting particles of said selected isotope to a level below ionization therefor; applying to the excited particles photons of energy sufficient to further excite the particles to a bound energy state substantially above the ionized level, and which bound state has a short but finite life time, substantially less than a nanosecond before degenerating to an ion and released electron; the energy of said photons spanning an energy range sub-stantially greater than the isotope shift for isotopes of said plural isotope types including the selected isotope type and centered on an absorption peak for said particles which is greater by at least an order of magnitude than the absorption for immediately neighboring photon energies.
Claim 19
Independent Claim
136 words
A method for ionizing particles of a selected isotope type in an environment of plural isotope types including the steps of: selectively exciting particles of said selected isotope to a level below ionization therefor; applying to the excited particles photons of energy sufficient to further excite the particles to a bound energy state substantially above the ionized level, and which bound state has a short but finite life time, substantially less than a nanosecond before degenerating to an ion and released electron; the energy of said photons spanning an energy range sub-stantially greater than the isotope shift for isotopes of said plural isotope types including the selected isotope type and centered on an absorption peak for said particles which is greater by at least an order of magnitude than the absorption for immediately neighboring photon energies.
Claim 20
Dependent Claim
15 words
The method of claim 17 wherein said energy range is at least approximately 1.5 cm-1.
Claim 21
Dependent Claim
25 words
The method of claim 17 wherein said excited state life time is approximately 10-11 seconds and said energy range is at least approximately 100 GHZ.
Claim 22
Dependent Claim
27 words
The method of claim 17 wherein said bound excited state is within the range of approximately 50 to 300 cm-1 above the ionization level for said particles.
Claim 23
Dependent Claim
19 words
The method of claim 17 wherein the energy of the applied photons corresponds approximately to 5800 to 6000 angstroms.
Claim 24
Dependent Claim
64 words
A process for identifying ionization peaks comprising: exciting particles to an excited level below the ioniza-tion level therefor; applying to said particles photons of energy sufficient to ionize the excited particles; varying the energy of the applied radiation over a range of energies to excite said particles to above ionization; and detecting the absorption rate for the applied photons as a function of energy.
Claim 25
Dependent Claim
64 words
A process for identifying ionization peaks comprising: exciting particles to an excited level below the ioniza-tion level therefor; applying to said particles photons of energy sufficient to ionize the excited particles; varying the energy of the applied radiation over a range of energies to excite said particles to above ionization; and detecting the absorption rate for the applied photons as a function of energy.
Claim 26
Dependent Claim
110 words
Apparatus for ionizing particles of a selected isotope type in an environment of plural isotope types comprising: means for selectively exciting the particles of said selected isotope type in one or more energy steps to an excited state; means for applying electromagnetic radiation of a pre-determined spectral width and frequency and tuned to an absorption line for the particles in said excited state which both excites the particles from the excited state to a state within a predetermined energy range above the ionization level and excites the particles with a predetermined fre-quency which is absorbed more strongly than absorption at immediately adjacent frequencies by at least an order of magnitude.
Claim 27
Dependent Claim
110 words
Apparatus for ionizing particles of a selected isotope type in an environment of plural isotope types comprising: means for selectively exciting the particles of said selected isotope type in one or more energy steps to an excited state; means for applying electromagnetic radiation of a pre-determined spectral width and frequency and tuned to an absorption line for the particles in said excited state which both excites the particles from the excited state to a state within a predetermined energy range above the ionization level and excites the particles with a predetermined fre-quency which is absorbed more strongly than absorption at immediately adjacent frequencies by at least an order of magnitude.
Claim 28
Dependent Claim
25 words
The apparatus of claim 23 wherein the means for selec-tively exciting includes means for exciting in at least three energy steps to said excited state.
Claim 29
Dependent Claim
20 words
The apparatus of claim 23 wherein said electromagnetic radiation is tuned within a range of approximately 5,800 to 6,000 angstroms.
Claim 30
Dependent Claim
20 words
The apparatus of claim 23 wherein said predetermined energy range is approximately 50 to 300 cm-1 above the ionization level.
Claim 31
Dependent Claim
50 words
The apparatus of claim 23 wherein: the means for selectively exciting includes means for applying at least one frequency of narrow band radiation tuned selectively for an absorption line of said selected isotope; and said predetermined spectral width is substantially greater than the spectral width of said narrow band radia-tion.
Claim 32
Dependent Claim
20 words
The apparatus of claim 27 wherein said predetermined spectral width is on the order of magnitude of approximately 0.5 angstroms.
Claim 33
Dependent Claim
11 words
The apparatus of claim 23 wherein said particles include uranium atoms.
Claim 34
Dependent Claim
13 words
The apparatus of claim 29 wherein the selected isotope is the U-235 isotope.
Claim 35
Dependent Claim
23 words
The apparatus of claim 23 further including means for separating the particles excited to said state above the ionization level from said environment.
Claim 36
Dependent Claim
18 words
The apparatus of claim 31 wherein said separating means includes means for applying crossed electric and magnetic fields.
Claim 37
Dependent Claim
12 words
The apparatus of claim 23 wherein said electromagnetic radiation includes laser radiation.
Claim 38
Dependent Claim
19 words
The apparatus of claim 23 wherein said means for selec-tively exciting includes means for exciting in two energy steps.
Claim 39
Dependent Claim
136 words
Apparatus for ionizing particles of a selected isotope type in an environment of plural isotope types including: means for selectively exciting particles of said selected isotope to a level below ionization therefor; means for applying to the excited particles photons of energy sufficient to further excited the particles to a bound energy state substantially above the ionized level, and which bound state has a short but finite life time, substantially less than a nanosecond before degenerating to an ion and released electron; the energy of said photons spanning an energy range substantially greater than the isotope shift for isotopes of said plural isotope types including the selected isotope type and centered on an absorption peak for said particles which is greater by at least an order of magnitude than the absorption for immediately neighboring photon energies.
Claim 40
Dependent Claim
136 words
Apparatus for ionizing particles of a selected isotope type in an environment of plural isotope types including: means for selectively exciting particles of said selected isotope to a level below ionization therefor; means for applying to the excited particles photons of energy sufficient to further excited the particles to a bound energy state substantially above the ionized level, and which bound state has a short but finite life time, substantially less than a nanosecond before degenerating to an ion and released electron; the energy of said photons spanning an energy range substantially greater than the isotope shift for isotopes of said plural isotope types including the selected isotope type and centered on an absorption peak for said particles which is greater by at least an order of magnitude than the absorption for immediately neighboring photon energies.
Claim 41
Dependent Claim
15 words
The apparatus of claim 35 wherein said energy range is at least approximately 1.5 cm-1.
Claim 42
Dependent Claim
25 words
The apparatus of claim 35 wherein said excited state life time is approximately 10-11 seconds and said energy range is at least approximately 100 GHZ.
Claim 43
Dependent Claim
27 words
The apparatus of claim 35 wherein said bound excited state is within the range of approximately 50 to 300 cm-1 above the ionization level for said particles.
Claim 44
Dependent Claim
19 words
The apparatus of claim 35 wherein the energy of the applied photons corresponds approximately to 5800 to 6000 angstroms.
Claim 45
Dependent Claim
71 words
Apparatus for identifying ionization peaks comprising: means for exciting particles to an excited level below the ionization level therefor; means for applying to said particles photons of energy sufficient to ionize the excited particles; means for varying the energy of the applied radiation over a range of energies to excite said particles to above ionization; and means for detecting the absorption rate for the applied photons as a function of energy.
Claim 46
Dependent Claim
71 words
Apparatus for identifying ionization peaks comprising: means for exciting particles to an excited level below the ionization level therefor; means for applying to said particles photons of energy sufficient to ionize the excited particles; means for varying the energy of the applied radiation over a range of energies to excite said particles to above ionization; and means for detecting the absorption rate for the applied photons as a function of energy.
References Cited (Backward Citations)
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