US 5,338,931 AGranted

Photoionization ion mobility spectrometer

AssigneeEnvironmental Technologies Group, Inc.

InventorsGlenn E. Spangler, Joseph E. Roehl, Gautam B. Patel, Alvin Dorman

Life of this patent

Estimating the term…

Loading patent…

Abstract

An improved photoionization ion mobility spectrometer is disclosed which utilizes a flashlamp as the source for ionization. A gas sample is introduced via a carrier gas into a ionization chamber which is part of the spectrometer cell. Ionizable molecules contained in the injected gas sample are ionized by the ultraviolet light emitted from the flashlamp. The ionized molecules are attracted by an electrostatic drift field into a drift chamber and travel therethrough against the flow of a drift gas counter-current thereto until they are captured by a collector located in the drift chamber opposite to the ionization chamber. A dopant with an effective ionization potential lower than the photon energy of the emitted light can be introduced into the ionization chamber to further improve the sensitivity and specificity.

Claims24

Dependent claims

An improved photoionization ion mobility spectrometer system for the detection of ionizable chemical species, comprising:

(a) a housing having a main chamber therein, said main chamber comprising a photoionization chamber and a drift chamber;
(b) drift gas inlet passage in communication with said drift chamber for entering a drift gas therethrough;
(c) an exhaust passage in communication with said photoionization chamber for exiting said drift gas;
(d) pumping means for forcing said drift gas to travel in said main chamber in a first direction;
(e) a carrier gas inlet passage in communication with said photoionization chamber for introducing a carrier gas into said photoionization chamber;
(f) a gas sample inlet means in communication with said photoionizaton chamber for introducing a gas sample to be analyzed into said photoionization chamber;
(g) a lamp means exposed to said photoionization chamber for ionizing said gas sample therein to form ionized gas sample, said lamp means comprising
(i) an electrical pulse transformer,
(ii) a flashlamp filled with about two atmospheres of noble gas and sealed with a window for transmitting light with desired wavelength, and
(iii) said flashlamp further containing two electrodes and at least one trigger probe, said trigger probe being connected to said pulse transformer and said electrodes being connected to a capacitor of high energy, said capacitor being adapted to discharge when a trigger pulse from said pulse transformer causes an ionization of said noble gas in said flashlamp and a discharge of said capacitor;
(h) electrode means for driving said ionized gas sample in said main chamber in a second direction countercurrent to said first direction;
and
(i) detector means placed in said drift chamber for detecting said ionized gas sample.

10 more elements

Dependencies are inferred from the claim text.