A beam ionization gauge (BIG) detector is disclosed for use in spectroscopy and configured to receive an analyte beam along a beam path. The BIG detector includes a filament configured to emit electrons and a grid. The grid is positioned substantially adjacent to the filament and configured to produce ions by directing the electrons to collide with the analyte beam along the beam path. A collector is positioned substantially adjacent to the grid to define the beam path therebetween and configured to detect the ions produced by the collisions of electrons with the analyte beam.

A miniature, low cost mass spectrometer capable of unit resolution over a mass range of 10 to 50 AMU. The mass spectrometer incorporates several features that enhance the performance of the design over comparable instruments. An efficient ion source enables relatively low power consumption without sacrificing measurement resolution. Variable geometry mechanical filters allow for variable resolution. An onboard ion pump removes the need for an external pumping source. A magnet and magnetic yoke produce magnetic field regions with different flux densities to run the ion pump and a magnetic sector mass analyzer. An onboard digital controller and power conversion circuit inside the vacuum chamber allows a large degree of flexibility over the operation of the mass spectrometer while eliminating the need for high-voltage electrical feedthroughs. The miniature mass spectrometer senses fractions of a percentage of inlet gas and returns mass spectra data to a computer.

Provided herein is an ion source containing a plurality of components, at least one of which is partially coated with a layer of silicon. The ion source reduces reactivity between the sample and the carrier gas, reduces or eliminates tailing in ion chromatograms, and/or improves mass spectral fidelity. Also provided are methods of using the ion source in a mass spectrometer or gas chromatograph-mass spectrometer.

The present system is a filament and an ion guide configuration. The ion source and an ion guide are combined in one system to create a fast release of ions, with increased efficiency of ion transport. The present device is a high-efficiency ion source operating at very low up to a few Torr pressure. Ions generated from the source immediately introduced into or created in an ion guide. The ions are introduced in or around the zero field lines of the RF field. Therefore, they will be trapped under the influence of the RF field there and can be transported to the next region of the mass spectrometer device. One method of transferring ions is by using ion-guides. Multipole ion guides have efficiently transferred ions through a vacuum or partial vacuum into mass analyzers. In particular, multipole ion guides have been configured to transport ions from a higher pressure region of a mass spectrometer to the lower pressure and then vacuum where the analyzer is operational.

The indirectly heated cathode ion source assembly employs a cathode cup unit and filament arrangement wherein the filament has a flat face spaced from a tungsten disc-shaped body and is disposed in a space that is surrounded by a thermal barrier to reduce thermal losses. The thermal barrier is formed by a plurality of concentric foils that are closely spaced.

A method of static gas mass spectrometry is provided. The method includes the steps of: introducing a sample gas comprising two or more isotopes to be analyzed into a static vacuum mass spectrometer at a time, t.sub.0; operating an electron impact ionization source of the mass spectrometer with a first electron energy below the ionization potential of the sample gas for a first period of time that is following t.sub.0 until a time t.sub.1; and operating the electron impact ionization source with a second electron energy at least as high as the ionization potential of the sample gas for a second period of time that is after time t.sub.1. The first time period from t.sub.0 to t.sub.1 is a period corresponding to a period taken for the isotopes of the sample gas to equilibrate in the mass spectrometer. A constant ion source temperature is preferably maintained. Also provided is a static gas mass spectrometer.

An ion source is configured for soft electron ionization and produces a low electron-energy, yet high-intensity, electron beam. The ion source includes an electron source that produces the electron beam and transmits it into an ionization chamber. The electron beam interacts with sample material in the ionization chamber to produce an ion beam that may be transmitted to a downstream device. The electron source is configured for generating a virtual cathode upstream of the ionization chamber, which enhances the intensity of the electron beam.

Method for producing multiply-charged helium nanodroplets and charged dopant clusters and nanoparticles out of the helium nanodroplets, the method comprising: producing neutral helium nanodroplets in a cold head (1) via expansion of a pressurized, pre-cooled, supersonic helium beam of high purity through a nozzle (3) into high vacuum with a base pressure under operation preferably below 20 mPa, ionizing the helium nanodroplets by electron impact (15), wherein the electron impact (15) leads to multiply-charged helium nanodroplets, doping the charged helium nanodroplets with dopant vapor in the pickup cell (19), wherein the doped nanodroplets form cluster ions with the initial charges acting as seeds, wherein the size of the nanoparticles can vary from a few atoms up to 105 atoms by arranging the size of the neutral helium nanodroplets, the charge of the helium nanodroplets and the density of dopant vapor in the pickup cell (19).

Apparatus (e.g., ion source), systems (e.g., residual gas analyzer), and methods provide extended life and improved analytical stability of mass spectrometers in the presence of contamination gases while achieving substantial preferential ionization of sampled gases over internal background gases. One embodiment is an ion source that includes a gas source, nozzle, electron source, and electrodes. The gas source delivers gas via the nozzle to an evacuated ionization volume and is at a higher pressure than that of the evacuated ionization volume. Gas passing through the nozzle freely expands in an ionization region of the ionization volume. The electron source emits electrons through the expanding gas in the ionization region to ionize at least a portion of the expanding gas. The electrodes create electrical fields for ion flow from the ionization region to a mass filter and are located at distances from the nozzle and oriented to limit their exposure to the gas.

Among other things, we describe methods and apparatus for the ionization of target molecular analytes of interest, e.g., for use in mass spectrometry. In some implementations, a thin molecular stream is emitted in either single or a split mode and encounters both an electron-impact ion source and trochoidal electron monochromator placed sequentially or coincidently. The first ion source emits high-energy electrons (70 eV) to generate characteristic positively-charged mass fragment spectra while the second source emits low-energy electrons in a narrow bandwidth to generate negative molecular ions or other ions via electron capture ionization. The dual ion source may be coupled to analytical instruments such as a gas chromatograph and to any number of mass analyzers such as a polarity switching quadrupole mass analyzer or to multiple mass analyzers.