Patent ID: 6509562
Filing Date: 2003-01-21
Classification: G01N

Abstract:
A photo-onization detector comprising:an ionization chamber; a drift chamber adjacent the ionization chamber; a photo-ionization source mounted to illuminate the ionization chamber and generate ions from a sample in the ionization chamber, wherein the photo-ionization source produces a plurality of UV spectra for illumination of the ionization chamber; and a control coupled to the photo-ionization source, wherein the control selects which of the plurality of UV spectra the photo-ionization source provides for illumination during a measurement using the drift chamber to determine ion mobility; wherein the photo-ionization source comprises a UV lamp; the UV lamp has a window that transmits UV light for illumination of the ionization chamber; the window comprises a plurality of window zones, each window zone transmitting a corresponding one of the plurality of UV spectra; wherein the control comprises a zone selector mounted between the window and the ionization chamber, the zone selector being movable to position an opening in the zone selector so that the zone selector blocks UV light to the ionization chamber from all window zones except one.