Abstract

Resonant two-photon ionization (R2PI) has been demonstrated for several classes of biomolecules in a supersonic jet. These thermally labile and nonvolatile species have been vaporized with pulsed laser desorption, with the use of a CO₂ laser from a ceramic surface with subsequent entrapment in a jet expansion. R2PI is then demonstrated in a time-of-flight mass spectrometer (TOFMS) with the use of ultraviolet laser radiation at either 280 or 266 nm. The 280-nm wavelength is found to be a fairly general tool for exciting the π-π* transition of the molecules under study, <i>viz</i>., metabolites of catecholamines, indoleamines, and tyrosine near their respective origin regions. The resulting mass spectra exhibit soft ionization where either molecular ions or minimal fragmentation is produced. At frequencies of much higher energy than that of the origin, fragmentation becomes increasingly difficult to prevent.

Use of two-photon excitation in resonance ionization mass spectrometry

E. C. Apel, J. E. Anderson, R. C. Estler, N. S. Nogar, and C. M. Miller
Appl. Opt. 26(6) 1045-1050 (1987)

Ultrasensitive detection of atmospheric constituents by supersonic molecular beam, multiphoton ionization, mass spectroscopy

Jack A. Syage, James E. Pollard, and Ronald B. Cohen
Appl. Opt. 26(17) 3516-3520 (1987)

Resonance-ionization mass spectrometry of carbon

L. J. Moore, J. D. Fassett, J. C. Travis, T. B. Lucatorto, and C. W. Clark
J. Opt. Soc. Am. B 2(9) 1561-1565 (1985)

Molecular analysis by ionization of laser-desorbed neutral species

Keith R. Lykke, Peter Wurz, Deborah H. Parker, and Michael J. Pellin
Appl. Opt. 32(6) 857-866 (1993)

Chemical ionization Fourier transform mass spectrometry of chemical warfare agent simulants using laser-produced metal ions

Chih-Cong Chou and S. Randolph Long
Appl. Opt. 29(33) 4981-4986 (1990)