Ultrasensitive method for measuring isotope abundance ratios
US4734579A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 7, 1986 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Jul 7, 2006 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01D59/44
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
An ultrasensitive mass spectrometry method based on multiphoton sub-Doppler resonance ionization to measure abundance sensitivities. The method preferentially ionizes a selected isotope in a sample by using Doppler-free resonant multiphoton ionization to produce an enhanced ratio of selected isotopes. Background species are separately ionized and rejected. As necessary or desired, selected isotope ions are preferentially ionized by using a second Doppler-free resonant multiphoton ionization to provide an additional isotope enhancement. The ions produced are injected into a mass spectrometer. Isotopic spectrum analysis of the ions is performed by the spectrometer and the ions are then detected by a detector such as a particular photon multiplier capable of observing a single ion. In one embodiment, at least one of the steps of preferentially ionizing the selected isotope is accomplished by two counter propagating laser beams of slightly different frequencies. Further improved sensitivity is achieved by: (1) using a frequency offset of the laser frequency in an amount proportional to the laser intensity to overcome AC Stark shifts, and (2) withdrawing ions for mass separation from on…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.