Field-induced ionization and Coulomb explosion of CO2 by intense femtosecond laser pulses

Field-induced ionization and Coulomb explosion of the triatomic molecule CO2 were systematically investigated by using a time-of-fight (TOF) mass spectrometer under an intense femtosecond laser field of different polarization with the intensities from 1.0×1015W/cm2 to 1.2×1016W/cm2. The appearances of the highly charged atomic ions and the peak splitting indicate that these atomic ions originate from Coulomb explosion of the highly charged molecular ions. The Coulomb explosion was proved to be a concerted process and two CO bonds broke simultaneously. Compared with the linearly polarized light, suppression of ionization occurs for the elliptically and circularly polarized lights. The angular distributions of the parent molecular ions are all isotropic. The collinear Om+ (m≤3) and orthogonal Cn+ (n≤3) distributions show that the molecule structure is being distorted and bent by the intense laser field. Analyzing the signal intensities obtained using linearly polarized light and circularly polarized light with equal electric field amplitude, the dynamic alignment mechanism is revealed to be responsible for the anisotropic angular distributions of Om+ (m≤3) and Cn+ (n≤3) ions.