Sequential multiphoton excitation method

Claim 2

A multiphoton excitation method comprising the sequential steps of: (a) exposing a gaseous material comprising polyatomic molecules to infrared laser radiation of a first predetermined wavelength to excite the polyatomic molecules to excited vibrational states of the ground electronic state and (b) after a time delay that is shorter than the vibrational but longer than the rotational relaxation time of the polyatomic molecule, exposing the material to infrared laser radiation of a second predetermined wavelength to further excite the molecules to produce a state at which the excited molecules undergo a chemical reaction.

Claim 3

An isotope enrichment and separation method comprising the sequential steps of: (a) exposing a gaseous material of polyatomic molecules comprising a particular isotope of an element and at least one other isotope of the same element to infrared laser radiation of a first predetermined wavelength to preferentially excite the polyatomic molecules containing the particular isotope of the element to excited vibrational states of the ground electronic state, (b) after a time delay that is shorter than the vibrational but longer than the rotational relaxation time of the polyatomic molecule, exposing the material to infrared laser radiation of a second predetermined wavelength whereby the excited molecules, enriched in the particular isotope, are further excited to produce a state at which the excited molecules undergo a chemical reaction, and (c) separating the resultant reaction product, enriched in the particular isotope, from the remainder of the material.

Claim 4

An isotope enrichment and separation method comprising the sequential steps of: (a) exposing a gaseous material of polyatomic molecules comprising a particular isotope of an element and at least one other isotope of the same element to infrared laser radiation of a first predetermined wavelength to preferentially excite the polyatomic molecules containing the particular isotope of the element to excited vibrational states of the ground electronic state, (b) after a time delay that is shorter than the vibrational but longer than the rotational relaxation time of the polyatomic molecule, exposing the material to infrared laser radiation of a second predetermined wavelength whereby the excited molecules, enriched in the particular isotope, are further excited to produce a state at which the excited molecules undergo a chemical reaction, and (c) separating the resultant reaction product, enriched in the particular isotope, from the remainder of the material.

Claim 5

The process of claim 2 in which the material is a hydrofluorocarbon of the formula HCF 2 X, wherein X is F, CF 3 , CHF 2 , CH 2 F, or CH 3 .

Claim 6

The process of claim 3 in which the material is trifluoromethane.

Claim 7

The process of claim 2 in which the material is expanded through a nozzle to form a molecular beam, and exposure to the first and second predetermined wavelengths is effected at spaced-apart points along the beam path.

Claim 8

The process of claim 5 in which the material comprises UF 6 .

Claim 9

The process of claim 1 or 2 in which the first and second predetermined wavelengths are substantially equal.

Claim 10

The process of claim 1 or 2 in which the first predetermined wavelength is selected to have a photon energy approximately corresponding to the energy difference between the ground and first excited vibrational states of the molecule and the second predetermined wavelength is selected to have a photon energy approximately corresponding to the difference between the first and second excited vibrational states of the molecule.

Claim 11

The process of claim 1 or 2 in which the material is selected from a group consisting of SF 6 , BCl 3 , D 2 CO 3 , and gaseous aliphatic hydrofluorocarbons having two or fewer carbon atoms.

Claim 12

The process of claim 1 or 2 in which the material further comprises a gas selected from a group consisting of N 2 , O 2 , CO, NO 2 , and the noble gases.