Probing trapped ion energies in a quadrupole ion trap mass spectrometer

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:7112355

Basic, C

This dissertation presents a series of studies elucidating the energies of ions stored in a quadrupole ion trap mass spectrometer. Two kinetic and three thermodynamic thermometer reactions are used to assign ion energies when no supplemental resonant excitation potentials are employed. The collision-induced dissociation, CID, breakdown graphs for a series of small molecules are then used to determine average ion internal energies upon application of an excitation potential to effect CID. Rate constants for the charge exchange reaction of Ar[sup +] with N[sub 2] and for the reaction of O[sub 2][sup +] with CH[sub 4] are used to assign center-of-mass kinetic energies, K.E.[sub cm], to ions as a function of the neutral pressures, the q[sub z] value of the ion, and the pressure of the He buffer gas. The K.E.[sub cm] values reflect anticipated trends in ion energy and range from 0.1 to 0.3eV. These values correspond to effective ion temperatures for the He buffered Ar[sup +] ions of [approx]1700K to 3300K. The ion-molecule equilibrium constants, K[sub eq], for the proton transfer reactions of protonated toluene with ethylbenzene, and of protonated diethylamine with di-n-propylamine, and the charge exchange reaction of ionized fluorobenzene with m-dichlorobenzene are used to calculate temperatures of ions stored for 2 to 10s. The CID breakdown graphs for ionized acetone, 2-propanone, propane, toluene, and benzene are compared to the corresponding graphs calculated from quasi-equilibrium theory, QET. The CID breakdown surfaces for the molecular ions of n-butylbenzene, n-pentylbenzene, n-hexylbenzene, and n-octylbenzene are used to assign average ion internal energies upon resonance excitation on the 91[sup +]/92[sup +] fragment ion ratios. The internal energies range from 3 to 8eV based on the excitation amplitude and time and increase with increasing size of the n-alkyl group.

• Research Organization: Florida Univ., Gainesville, FL (United States)
• OSTI ID: 7112355
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IONS
KINETIC ENERGY
TEMPERATURE MEASUREMENT
TRAPPING
MASS SPECTROMETERS
THERMODYNAMIC PROPERTIES
AMINES
ARGON IONS
HYDROCARBONS
METHANE
NITROGEN
OXYGEN IONS
QUADRUPOLES
ALKANES
CHARGED PARTICLES
ELEMENTS
ENERGY
MEASURING INSTRUMENTS
MULTIPOLES
NONMETALS
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
SPECTROMETERS
664000* - Atomic & Molecular Physics- (1992-)
400102 - Chemical & Spectral Procedures