Ionisation and fragmentation dynamics of laser desorbed polycyclic aromatic hydrocarbons using femtosecond and nanosecond post-ionisation

L. Robson, A.D. Tasker, K.W.D. Ledingham, P. McKenna, T. McCanny, C. Kosmidis, P. Tzallas, D.A. Jaroszynski, D.R. Jones

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Nanosecond laser desorption/femtosecond laser mass spectrometry (LD/FLMS) incorporating a reflectron time-of-flight mass spectrometer has been used to study the ionisation/fragmentation of polycyclic aromatic hydrocarbons (PAHs) in intense laser fields (7.0×1014 to 9.3×1015 W cm−2). Pulses of 80 fs, 800 nm have been used to post-ionise the PAHs anthracene, tetracene and pentacene. For each molecule strong singly and doubly charged parent ions are observed accompanied by fragmentation. In addition, strong triply charged parent ions (M3+) are observed for anthracene and weaker M3+ signals for tetracene and pentacene are also observed. Nanosecond post-ionisation (266 nm, 16 ns) spectra of the molecules have been recorded and are included for comparison with the femtosecond data. Similarities in the observed fragmentation pattern of low-mass fragments of the nanosecond and low intensity femtosecond spectra are highlighted. In addition, as the laser intensity increases, it is observed that fragmentation pathways preferentially switch from CmH3+ ion yield to Cm+ production for m=2-5 at a critical intensity which is molecule dependent.
Original languageEnglish
Pages (from-to)69-85
Number of pages16
JournalInternational Journal of Mass Spectrometry
Volume220
Issue number1
DOIs
Publication statusPublished - 15 Sep 2002

Keywords

  • laser desorption
  • femtosecond laser
  • mass spectrometry
  • polycyclic aromatic hydrocarbon
  • PAHs
  • multiply charged ions
  • field ionisation

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