scholarly journals A continuous flow probe method for on‐line introduction of liquid samples for detection by laser desorption with resonant two‐photon ionization in supersonic beam mass spectrometry

1991 ◽  
Vol 62 (4) ◽  
pp. 957-962 ◽  
Author(s):  
David A. Lustig ◽  
David M. Lubman
Keyword(s):  
Mass Spectrometry ◽  
Continuous Flow ◽  
Laser Desorption ◽  
Probe Method ◽  
Flow Probe ◽  
Two Photon ◽  
Liquid Samples ◽  
On Line ◽  
Photon Ionization

Resonant Two-Photon Ionization of CBZ-Derivatized Nonaromatic Peptides Using Pulsed Laser Desorption in Supersonic Beam Mass Spectrometry

1988 ◽  
Vol 42 (3) ◽  
pp. 411-417 ◽  
Author(s):  
Liang Li ◽  
David M. Lubman
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Pulsed Laser ◽  
Laser Desorption ◽  
Small Peptides ◽  
Neutral Species ◽  
Supersonic Expansion ◽  
Two Photon ◽  
Photon Ionization ◽  
Desorption Method

Resonant two-photon ionization (R2PI) of nonaromatic peptides is studied with the use of CBZ-derivatization as a means of providing an absorbing aromatic center in the near-UV region at 266 nm. The peptides are then vaporized with a pulsed laser-induced desorption method, with subsequent entrainment of the desorbed neutral species into a supersonic expansion. The CBZ-derivatized peptides are then ionized and mass analyzed in a time-of-flight mass spectrometer. The resulting R2PI/MPI-induced fragmentation-ionization patterns generally yield the molecular ion as well as fragments due to specific bond cleavages which are characteristic of the structure of the peptide. Thus, the resulting mass spectra can be used for identification and structural analysis of these small peptides. Most significantly, the laser-induced fragmentation can be used to distinguish between isomeric peptides containing Ile, Leu, or Nle.

The spectroscopy of jet-cooled porphyrins: an insight into the vibronic structure of the Q band

2010 ◽  
Vol 14 (04) ◽  
pp. 314-323 ◽  
Author(s):  
Joseph M. Beames ◽  
Timothy D. Vaden ◽  
Andrew J. Hudson
Keyword(s):  
Laser Desorption ◽  
Electronic Transitions ◽  
Quantum Mechanical ◽  
Supersonic Expansion ◽  
Two Photon ◽  
Vibrational Levels ◽  
Inert Carrier ◽  
Mechanical Interpretation ◽  
Photon Ionization ◽  
Insight Into

We will present resonant two-photon ionization spectra for meso-tetraphenylporphyrin, H 2 TPP , measured under isolated conditions. The polycrystalline compound was vaporized, in vacuo, using both thermal and laser desorption, and seeded into a supersonic expansion of an inert-carrier gas. The molecules remain largely intact in the gaseous phase. However, the two techniques for vaporizing H 2 TPP give different internal temperatures for the isolated substrate, with greater vibrational cooling achieved using laser desorption. A comparison of the peak positions and intensities in the resonant two-photon ionization spectra of thermal- and laser-desorbed molecules provides an insight into the vibrational structure of the Q band. In particular, the greater contribution made by electronic transitions originating from higher vibrational levels in the ground state of H 2 TPP is emphasized. We conclude that vibronic coupling in the ground electronic state plays an important role in a quantum-mechanical interpretation of the Q band.

Applications of a continuous flow probe in FAB mass spectrometry

1987 ◽  
Vol 22 (9) ◽  
pp. 647-650 ◽  
Author(s):  
M. Barber ◽  
L. W. Tetler ◽  
D. Bell ◽  
A. E. Ashcroft ◽  
R. S. Brown ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Continuous Flow ◽  
Flow Probe ◽  
Fab Mass Spectrometry
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