title: A mass spectrometric investigation of isomers of butane.
abstract: BACKGROUND
  Butane is an important industrial chemical in which photo-processes are very important for the initiation of reactions. Recent advances in nanosecond pulsed laser technology have led to high laser intensities being available to researchers to enable these photo-processes to be studied in compounds such as butane.
  
  
  METHODS
  The photo-decomposition, dissociation and combustion mechanisms in the neutral butane molecule have been studied in detail, by investigating the multiphoton (MP) dissociative ionisation of its n- and i-isomers, using a time-of-flight mass spectrometer connected to a high power nanosecond laser system. The laser used was a Nd:Yag with a 5 ns pulse width operated at the fundamental wavelength (1064 nm) and the doubled and tripled wavelengths (532 nm and 355 nm). The fragmentation patterns for the isomers were determined for the three wavelengths as a function of laser intensity. Similar laser intensities of between 10(10) and 10(13) W/cm(2) were used at the three wavelengths: 1064, 532 and 355 nm.
  
  
  RESULTS
  The mass spectra of each isomer of the butane molecule display a very weak molecular ion and are dominated by fragment ion peaks. The degree of fragmentation increases as the laser intensity increases.
  
  
  CONCLUSIONS
  Depending on the wavelength some significant differences in the mass spectra of the two isomers were detected and it has been concluded that the isomerisation of i-butane to n-butane is a process which is faster than the duration of the laser pulse used.
authors.affiliation: University of Selcuk, Faculty of Science, Department of Physics, Konya 42031, Turkey.
authors.forename: Tuğbahan Yılmaz
authors.initials: TY
authors.lastname: Alıç
authors.forename: Hamdi
authors.initials: H
authors.lastname: Şükür Kılıç
authors.forename: Haziret
authors.initials: H
authors.lastname: Durmuş
authors.forename: Mevlüt
authors.initials: M
authors.lastname: Doğan
authors.forename: Ken W D
authors.initials: KW
authors.lastname: Ledingham