Interaction Mechanism of Some Alkyl Iodides with Femtosecond Laser Pulses

Abstract

The interaction of 1-iodopropane, 2-iodopropane, 1-iodobutane, 2-iodobutane, and 1-iodopentane with (5 × 10 13-5 × 10 15 W/cm 2 ) femtosecond laser fields is studied by means of a time-of-flight mass spectrometer. It is found that multiphoton ionization (MPI) and field ionization (FI) processes are involved in the molecular ionization. The contribution of these processes can be distinguished using the peak profile of the ions in the mass spectra. Thus, from the mass spectra of 2-iodoropane and 2-iodobutane, it is concluded that MPI processes are taking place even for Keldysh parameter values γ ∼ 0.3. The field ionization process depends on the characteristics of the molecular binding potential well and leads to an asymmetric charge distribution of the transient multiply charged parent ions. In the case of 1-iodobutane, the MPI processes lead to a stable doubly charged parent ion production with a laser intensity threshold higher than that found for I 2+ ions. In addition, the isomers studied exhibit distinct differences in their mass spectra and their origin is discussed in detail.

Molecular hydrogen ion elimination from alkyl iodides under strong laser beam irradiation

“…It should be mentioned that the above process is expected to contribute to the H 2 + signal only from ionic states (the contribution from neutral hydrogen molecules has been excluded above). It is worth noting that the dissociation to [P I] fragments has been identified even for the case of the femtosecond experiments [8].…”

“…Recently, we have studied the ionization/dissociation processes of some alkyl iodides by means of time-of-flight (TOF) mass spectrometry under strong (∼10 16 W cm −2 ) femtosecond [8] and picosecond [9,10] laser irradiation. In both cases, an intense ionic signal corresponding to atomic and molecular hydrogen ions has been recorded.…”

“…As mentioned above, H 2 + ions have been observed in the mass spectra of alkyl iodides [8,9,19,20] under strong femtosecond and picosecond laser irradiation but the mechanism involved remains largely unexplained. For instance, it has been suggested that when fluorobenzene is subjected to strong laser fields, the H atoms are ejected from the molecular skeleton very rapidly (within ∼7 fs) [21].…”

Multiple ionization and Coulomb explosion of molecules, molecular complexes, clusters and solid surfaces

“…Despite this, we have listed here only selected studies performed from 2004 to data on Coulomb explosion of isolated large molecules initiated by femtosecond laser pulses. The family of molecules include aliphatic and [52,125,[141][142][143][144][145][146][147][148][149][150][151][152][153][154][155][156][157][158][159] aromatic hydrocarbons [92,[160][161][162], halogenated molecules [33,42,[163][164][165][166][167][168][169][170][171][172][173][174][175][176] and alcohols [49,51,53,155,[177][178]…”

Highly Reliable Dynamic Random Access Memory Technology for Application Specific Memory with Dual Nitrogen Concentration Gate Oxynitrides Using Selective Nitrogen Implantation

“…Through a number of investigations, there have been the following findings. (1) The onset of PI occurs at peak power densities around 10 12 W cm −2 [66,67]. (2) Initially, multiphoton ionization is more important, with field ionization and fieldassisted dissociation growing in importance as the power densities increase [68][69][70][71].…”