Laser desorption Fourier transform ion cyclotron resonance (LD/FT/ICR) mass spectrometry for high mass ions

Miscellaneous · Fri Jan 01 00:00:00 EST 1993

OSTI ID:7015762

Wood, T D

The focus of this dissertation is the utility of laser desorption Fourier transform ion cyclotron resonance (LD/FT/ICR) mass spectrometry as a tool in analyzing high mass ions. Improved sensitivity for laser desorption is demonstrated when a solid state NH[sub 4]Br is coadded to aromatic hydrocarbon samples. The laser desorbs the salt into its ionic components; the cationic NH[sub 4][sup +] acts to selectively protonate neutral hydrocarbons generated by laser desorption via chemical ionization (LD/CI) to form (M + H)[sup +]. Laser desorption is also a useful tool for fullerene soot analysis. Small fullerenes coalesce to form even-numbered giant carbon clusters not originally present in the soot (C[sub n], N [ge] 100) in the positive ion mode when fullerene soots are applied as thick films. Toluene extracts of the soots heated in pressure bombs examined in positive and negative ion modes exhibit similar qualitative distributions of fullerene ions, provided thin-film conditions are maintained. Heretofore undiscovered dehydrogenated toluene-fullerene adducts (C[sub 2n]C[sub 7]H[sub 6], 102 [ge] 2n [ge] 60) were discovered in the bomb extracts. Derivations of the upper mass limits for matrix-assisted laser desorption FT/ICR showed that the axial upper limit is responsible for the poor mass range performance of this technique. Based on radial and axial limits, optimal trapping voltages were derived. The upper limit is increased by using high trapping voltages, gated trapping, and collisional cooling. Collisional cooling combined with quadrupolar excitation was shown to be an effective means of axializing ions for efficient sustained ion trapping with high mass resolving power and single-isotope ion isolation selectivity. The selectivity advantages was explored in detail.

• Research Organization: The Ohio State Univ., Columbus, OH (United States)
• OSTI ID: 7015762
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AMMONIUM COMPLEXES
ION CYCLOTRON RESONANCE SPECTROSCOPY
MASS SPECTRA
BROMIDES
FULLERENES
FOURIER TRANSFORM SPECTROMETERS
LASER SPECTROSCOPY
TRAPPING
BROMINE COMPOUNDS
CARBON
COMPLEXES
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
ION SPECTROSCOPY
MEASURING INSTRUMENTS
NONMETALS
SPECTRA
SPECTROMETERS
SPECTROSCOPY
400201* - Chemical & Physicochemical Properties