Two-Photon Ionization of Polyatomic Molecules in a Mass Spectrometer

1978 ◽  
Vol 33 (12) ◽  
pp. 1546-1548 ◽  
Author(s):  
U. Boesl ◽  
H. J. Neusser ◽  
E. W. Schlag
Keyword(s):  
Mass Spectrometer ◽  
Polyatomic Molecules ◽  
Dye Laser ◽  
Ionization Source ◽  
Two Photon ◽  
Photon Ionization ◽  
Tunable Frequency

Abstract Two-photon ionization of benzene molecules in a mass spectrometer is performed with a tunable frequency-doubled dye laser. The nonlinear ionization is resonantly enhanced by real intermediate rovibronic levels in the S1 state of the molecule. Our results show that stepwise multi-photon ionization is a very selective and versatile ionization source for a mass spectrometer.

scholarly journals Two-Color Two-Photon Ionization Spectrum of Pyrene in N-Hexane

1997 ◽  
Vol 17 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Keiji Nakashima ◽  
Hirofumi Soga ◽  
Teiichiro Ogawa
Keyword(s):  
Polar Solvent ◽  
Dye Laser ◽  
Ionization Threshold ◽  
Excitation Energies ◽  
Ionization Technique ◽  
Two Photon ◽  
Photoionization Process ◽  
Photon Ionization ◽  
Ionization Spectrum ◽  
Near Threshold

The photoionization process of pyrene in non-polar solvent has been investigated using a two-color two-photon ionization technique. The ionization spectrum near threshold of pyrene in n-hexane was measured by a delayed irradiation of a dye laser 20 ns after an N2 laser at total excitation energies of 5.9–6.22 eV. The two-photon ionization threshold of pyrene was in the vicinity of 5.9 eV which is larger by 0.7 eV than that expected from the onset of one-photon ionization. The ionization spectrum shows maxima at 5.92 and 5.99 eV which may be assigned to an autoionization process.

scholarly journals Preparation and Study of Single Sized Cluster Ions in a Supersonic Jet

1991 ◽  
Vol 11 (3-4) ◽  
pp. 225-230 ◽  
Author(s):  
E. W. Schlag ◽  
H. L. Selzle
Keyword(s):  
Mass Spectrometer ◽  
Time Scale ◽  
Supersonic Jet ◽  
Excess Energy ◽  
Cluster Ions ◽  
Mass Analysis ◽  
Two Photon ◽  
Supersonic Jet Expansion ◽  
Photon Ionization ◽  
Single Size

Experiments with supersonic jet expansion have been performed to prepare clusters of benzene molecules. The clusters produced in the jet are ionized by two-photon ionization and mass analysis is achieved in a reflectron time of flight mass spectrometer. Due to an excess energy up to several hundred me V unimolecular decay occurs on a time-scale from nanoseconds up to microseconds and even longer. To discriminate against interferences from fragmentation of higher mass clusters in the observed spectra different experiments have been performed which include a new method by which single size cluster ions are stopped in the supersonic jet. These ions then stay isolated in space and the metastable decay of these complexes can be analyzed without further perturbation from fragmentation of higher clusters.

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