title: Broad-band fourier transform quadrupole ion trap mass spectrometry.
abstract: Broad-band nondestructive ion detection is achieved in a quadrupole ion trap mass spectrometer by impulsive excitation of a collection of trapped ions of different masses and recording of ion image currents induced on a small detector electrode embedded in but isolated from the adjacent end cap electrode. The image currents are directly measured using a simple differential preamplifier, filter, and amplifier combination and then Fourier analyzed to obtain broad-band frequency domain spectra characteristic of the sample ions. The use of the detector electrode provides a significant reduction in capacitive coupling with the ring electrode. This minimizes coupling of the rf drive signal, which can saturate the front-end stage of the detection circuit and prevent measurement of the relatively weaker ion image currents. Although impulsive excitation is preferred due to its broad-band characteristics and simplicity of use, results are also given for narrow-band ac and broad-band SWIFT (stored wave-form inverse Fourier transform) excitation. Data using argon, acetophenone, and n-butylbenzene show that a resolution of better than 1000 is obtained with a detection bandwidth of 400 kHz. An advantage of nondestructive ion detection is the ability to measure a single-ion population multiple times. This is demonstrated using argon as the sample gas with an average remeasurement efficiency of >90%. Tandem mass spectrometry experiments using a population of acetophenone ions are also shown.
authors: Department of Chemistry, Purdue University, West Lafayette, Indiana 47907.
authors: M
authors: M
authors: Soni
authors: V
authors: V
authors: Frankevich
authors: M
authors: M
authors: Nappi
authors: R E
authors: RE
authors: Santini
authors: J W
authors: JW
authors: Amy
authors: R G
authors: RG
authors: Cooks