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Abstract No.: MoP-062
Session: Fundamentals: Theory and Experiment
Presentation date: Mon, Aug 28, 2006
Presentation time: 14:30 – 16:00

Polyaromatic Hydrocarbons Photoionization at 355nm and TOF Analysis

Juan Carlos Jaramillo Poveda1, Alfonso Tapia Guerrero1, Ignacio Torres Alvarez1, Carmen Gudino Cisneros1

1 Universidad Nacional Autonoma de Mexico, Cuernavaca, Mexico

Correspondence address: Juan Carlos Jaramillo Poveda, Universidad Nacional Autonoma de Mexico, Postgrado en Quimica, Av. Univesidad, Colonia Chamilpa, Cuernavaca, Morelos, 62210 Mexico.

Keywords: Hydrocarbons; Laser Ionization; Mass Spectrometry, Time of Flight; Multiphoton Ionization.

Novel aspect: New analysis in resonant and non-resonant photoionization of PAHs as about development of efficently techniques to analysis of solid matrices. IR vibrational desortion has been proved on very high complex systems.


In this work we were analyzed the photoionization of polyaromatic hydrocarbons (PAHs) using 355nm radiation from second harmonic of Nd:YAG laser in nanosecond regimen (8 ns pulse width and 10 Hz frequency). An molecular beam of naphthalene (NAP), phenanthrene (PHE), anthracene (ANT), pyrene (PYR), chrysene (CHR), perylene (PER), fluoranthene (FLU), 1,2-Benzanthracene (12BEN), 2,3-Benzanthracene (23BEN), and coronene (COR) (used as well received from Aldrich chemical Co.) was generated by thermal treatment (maximum temperature was thermocouple controlled)to increase the vapor pressure, differential vacuum introduce the sample vapor in ionization region through and skimmer (background pressure was 10-8 torr). The vibrational cooled molecular beam generated was ionized using energies from cero to 50 mJ by pulse (Intensity:106 Wcm-2), and the ions products from photoionization were analyzed using a TOF system. Non molecular ions were detected at the energy regime used, and a high molecular fragmentation and, double charged ions (Cn+2, n=1-5) as about very protonated carbon ions (CHn+, n=1-6, etc) were observed. Argon was used as carrier gas, and this effect on fragmentation, and the type ions products, and efficiency of fragmentation were studied. Maximum fragmentation yield was moved to high energies as a consequence of carrier gas.

1. J. W. Hager, S. C. Wallace, Anal. Chem. 60, 5 (1988).
2. H. W. Jochims, E. Ruhl, H. Baumgartel, S. Tobita, S. Leach, Int. J. Mass Spec. Ion Proc. 167/168 35 (1997).