Gaseous nitrogen detection using excited-state laser spectroscopy

Claim 1

A method of measuring the concentration of nitrogen molecules in a sample of unknown concentration, wherein the absorption of a comparable sample of known concentration has previously been measured, said method comprising the steps of: (a) energizing the sample of unknown concentration so that its molecules are in the ##EQU25## state; (b) measuring the absorption of the energized sample of unknown concentration by the direct optical absorption technique; and, (c) comparing the absorption of the sample of unknown concentration with the previously measured absorption of a comparable sample of known concentration.

Claim 2

A method of measuring the concentration of nitrogen molecules in a sample of unknown concentration, wherein the absorption of a comparable sample of known concentration has previously been measured, said method comprising the steps of: (a) energizing the sample of unknown concentration so that its molecules are in the ##EQU25## state; (b) measuring the absorption of the energized sample of unknown concentration by the direct optical absorption technique; and, (c) comparing the absorption of the sample of unknown concentration with the previously measured absorption of a comparable sample of known concentration.

Claim 8

A method for measuring the concentration of nitrogen molecules in a sample, comprising the steps of: (a) introducing into a sample chamber a first sample of gas having a known concentration of nitrogen molecules; (b) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the sample chamber; (c) measuring the intensity N 0 of the beam after it has passed through the sample chamber containing the first sample; (d) energizing the sample sufficiently to raise the nitrogen molecules to the normally unpopulated ##EQU27## energy level, which differs in energy from a higher energy level B 3 πg by an energy difference corresponding to a photon wavelength of between 670 and 880 nm; (e) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the energized first sample; (f) measuring the intensity N E of the beam after it has passed through the sample chamber including the energized sample; (g) determining the reduction in intensity N 0 -N E that results from energizing the sample; (h) replacing the first sample of known concentration by a second sample having an unknown concentration of nitrogen molecules; (i) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the sample chamber; (j) measuring the intensity X 0 of the beam of photons after it has passed through the sample chamber containing the second sample; (k) energizing the second sample in such a way that the nitrogen molecules in it are raised to the normally unpopulated ##EQU28## energy level, which differs in energy from a higher energy level B 3 πg by an energy difference corresponding to a photon wavelength of between 670 and 880 nm; (l) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the energized second sample; (m) measuring the intensity X E of the beam that has passed through the sample chamber including the energized second sample; (n) determining the reduction in intensity X 0 -X E associated with energizing the second sample; (o) calculating the concentration of nitrogen molecules in the second sample by the equation ##EQU29##

Claim 9

A method for measuring the concentration of nitrogen molecules in a sample, comprising the steps of: (a) introducing into a sample chamber a first sample of gas having a known concentration of nitrogen molecules; (b) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the sample chamber; (c) measuring the intensity N 0 of the beam after it has passed through the sample chamber containing the first sample; (d) energizing the sample sufficiently to raise the nitrogen molecules to the normally unpopulated ##EQU27## energy level, which differs in energy from a higher energy level B 3 πg by an energy difference corresponding to a photon wavelength of between 670 and 880 nm; (e) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the energized first sample; (f) measuring the intensity N E of the beam after it has passed through the sample chamber including the energized sample; (g) determining the reduction in intensity N 0 -N E that results from energizing the sample; (h) replacing the first sample of known concentration by a second sample having an unknown concentration of nitrogen molecules; (i) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the sample chamber; (j) measuring the intensity X 0 of the beam of photons after it has passed through the sample chamber containing the second sample; (k) energizing the second sample in such a way that the nitrogen molecules in it are raised to the normally unpopulated ##EQU28## energy level, which differs in energy from a higher energy level B 3 πg by an energy difference corresponding to a photon wavelength of between 670 and 880 nm; (l) periodically directing a beam of photons having a wavelength between 670 and 880 nm through the energized second sample; (m) measuring the intensity X E of the beam that has passed through the sample chamber including the energized second sample; (n) determining the reduction in intensity X 0 -X E associated with energizing the second sample; (o) calculating the concentration of nitrogen molecules in the second sample by the equation ##EQU29##