Abstract: This invention provides a means of detecting unlabeled DNA or RNA following hybridization to an immobilized, labeled DNA probe. The immobilized DNA oligomers (probes) form a hairpin structure containing a unique restriction site that persists only when hybridization to the internal target-hybridization sequence has not occurred. Restriction enzyme digestion of unhybridized, labeled DNA probes at or above room temperature detaches the label from the surface and the label is washed away. The hairpin structure is disrupted when hybridization of the internal target-hybridization sequence occurs, removing the restriction site and preventing cleavage. In this case, the labels on target-hybridized probes remain bound to the substrate and are detected. In its preferred embodiment, a bioluminescent label is located on one end of the probe and a surface attachment moiety is on the other.

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.

Abstract: A dosimeter which incorporates new methods for determining neutron dose. Less than one millirad of dose due to neutrons of all energies down to approximately 10.sup.3 eV can be measured, and the response can be adjusted by design of the dosimeter. The dosimeter utilizes the sputtering of material from a target due to the action of the neutrons and measuring of the amount of sputtered material to determine the dose. The sputtered material may be, for example, a noble gas or an inert solid. Various radiator materials can be included to interact with the neutrons so that the resulting charged particles control the sputtering process and hereby increase the sensitivity of the dosimeter. The target material can be, for example, noble-gas-impregnated polycrystalline or amorphous metals. The sputtered material is analyzed using resonance ionization spectroscopy, sputter-initiated resonance ionization spectroscopy or other methods to determine its quantity and hence the neutron dose.

Abstract: An ultrasensitive mass spectrometry method based on multiphoton sub-Doppler resonance ionization is used 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. 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 (24). Isotopic spectrum analysis of the ions is performed by the spectrometer (24) and the ions are then detected by a detector (26) 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.