Comparative Study of Multielectron Ionization of Alkyl Halides Induced by Picosecond Laser Irradiation

Abstract

The interaction of C2H5X, 1-C3H7X, 1-C4H9X, where X = I, Br, Cl, with strong (1 x 10(13)-1.2 x 10(14) W/cm2) 35 ps laser pulses at 1064 nm is studied by means of time-of-flight mass spectrometry. The multielectron ionization following the C-X bond elongation has been verified for the studied molecules. By combination of the intensity dependence of the ion yields, the estimated kinetic energies of the released fragment ions, and their angular distributions, we have identified the different dissociation channels of the transient multiply charged parent ions. From the dependence on the laser intensity of the ratio of the doubly charged halogen ions to the singly charged ones, it is concluded that the molecular coupling with the laser field increases with the molecular size.

Systematic Trends in Photonic Reagent Induced Reactions in a Homologous Chemical Family

“…Thus, the origin of this behavior is likely electronic in nature and may be due to greater excess laser energy above the IE, but a full explanation of this trend would require further investigation, possibly aided by electronic structure calculations. Higher charge states of halogen ions follow the same trend, and often show the contribution of two or more distinct Coulomb explosion pathways (not shown), which has also been observed in other alkyl halides. ,, …”

“…Second, the highest charge states of the halogen ions are F + , Cl 4+ , Br 5+ , and I 6+ (these signals are typically too small to see on the scale in Figure a), regardless of the parent molecule. The independence of the highest halogen charge state on the parent molecule (e.g., all molecules containing Br have charge states up to Br 5+ in the TOF spectra) has been observed for molecules of the form C n H 2 n +1 X . The third common feature is that all of the TOF spectral signals from the halogen ions (both singly and multiply charged) have multipeak structures, as shown for the singly charged halogen ions in Figure b–d.…”

“…The independence of the highest halogen charge state on the parent molecule (e.g., all molecules containing Br have charge states up to Br 5+ in the TOF spectra) has been observed for molecules of the form C n H 2n+1 X. 44 The third common feature is that all of the TOF spectral signals from the halogen ions (both singly and multiply charged) have multipeak structures, as shown for the singly charged halogen ions in Figure 2b−d. The central peak marked with a number sign (#) arises from a singly charged precursor (likely M + ), while the two outer peaks marked with asterisks ( * ) arise from Coulomb explosion of a multiply charged precursor.…”

Multi-electron dissociative ionization of clusters under picosecond and femtosecond laser irradiation: the case of alkyl-halide clusters

“…This observation is not in agreement with the trend reported for the monomer case, where the laser/molecule coupling was found to increase with the molecular chain length. 25 This point reveals another difference in the MEDI process between the monomers and the clusters. Clearly, there is a variation in the involved MEDI mechanism and it will be discussed in a following paragraph in conjunction with other experimental features.…”

From Neutral Aniline to Aniline Trication: A Computational and Experimental Study

“…Fragments including C 3 H 3 + /C 6 H 6 2+ (violet in Figure c), NH 2 + (green in Figure b), and NH + (orange in Figure b) exhibit multiple peaks, indicating their formation from via Coulomb explosion of multiply charged precursors. − The split peaks marked with a symbol * appearing below and above the nominal m / z values arise from energetic fragments preferentially ejected toward and away from the detector, respectively, upon precursor breakup. Both NH 2 + and NH + fragments exhibit two pairs of Coulomb explosion peaks.…”