Utilizing an ultraintense (1016 W cm−2)
fs laser, the laser/matter interaction of the tetrahedral CH3I
molecule is investigated. A mass spectrum and the angular distributions
of fragment ions arising from Coulomb explosion of molecular ions,
obtained with linearly polarized light, are presented. The distributions
for In+ (n ≤ 7),
CHm+ (m ≤ 3),
Cp+ (p ≤ 4) and H+ ions
are all anisotropic and maximal when the polarization lies along the
spectrometer axis. The molecule hence seems to behave as a diatomic,
with the fragment ions being ejected along the field direction. Also
presented are mass spectra of the isomers 1- and 2-nitropropane, which
are explosive species, taken for horizontal and vertical polarizations
at both 375 and 750 nm. It is shown that femtosecond laser mass
spectrometry (FLMS) can be used to distinguish between these two isomers
through their differing dissociation patterns. Isomer identification
is important for many different applications and FLMS may provide
a means of achieving this for a wide range of molecules.