High pressure fluid pulsed injection in supersonic beam/mass spectrometry with resonant two-photon ionization

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6963310

Pang, H

The sample introduction of non-volatile and thermally labile compounds is an important problem in mass spectrometry. In this thesis, supercritical fluids (CO{sub 2}, N{sub 2}O, NH{sub 3}) and subcritical fluids (H{sub 2}O, CH{sub 3}OH) have been used to introduce these samples into a time-of-flight mass spectrometer with the use of a supersonic expansion. A high pressure pulsed valved, which is capable of withstanding pressures as high as 400 atm, has been constructed in order to inject these high pressure fluids into vacuum at 10{sup {minus}5} torr for supersonic expansions. The short pulses permit the use of a 200-330 {mu}m orifice in order to increase the molecular beam density without overloading the moderate size pumping system. Resonant two-photon ionization could then be used to produce either molecular ions or fragmentation using UV laser radiation at different wavelengths and powers. In addition, the absorption profile observed due to the absorption of the first photon becomes narrow because of the cooling effect of the supersonic expansion, even with the use of these polyatomic carrier fluids. Relatively sharp wavelength ionization spectra (<0.10nm) are obtained by monitoring the molecular ion intensity as a function of the laser wavelength. These wavelength ionization spectra can then be used for distinguishing sample compounds. Several classes of compounds, such as PAH's neuroleptic drugs, amines and small peptides, have been successfully introduced into the time-of-flight mass spectrometer by this high pressure fluid pulsed injection method with resonant two-photon ionization detection.

• Research Organization: Michigan Univ., Ann Arbor, MI (USA)
• OSTI ID: 6963310
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical &amp; Spectral Procedures
ALCOHOLS
AMINES
AMMONIA
AROMATICS
BIOLOGICAL MATERIALS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
CONTROL EQUIPMENT
ELECTROMAGNETIC RADIATION
EQUIPMENT
FLOW REGULATORS
FLUID INJECTION
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
IONIZATION
LASERS
MASS SPECTRA
MASS SPECTROSCOPY
MATERIALS
MEASURING INSTRUMENTS
METHANOL
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
NITROUS OXIDE
OPENINGS
OPERATION
ORGANIC COMPOUNDS
ORIFICES
OXIDES
OXYGEN COMPOUNDS
POLYCYCLIC AROMATIC HYDROCARBONS
PRESSURIZING
PULSE TECHNIQUES
RADIATIONS
SAMPLERS
SPECTRA
SPECTROMETERS
SPECTROSCOPY
SUPERCRITICAL STATE
TIME-OF-FLIGHT SPECTROMETERS
ULTRAVIOLET RADIATION
VALVES
WATER