Multiple ionization of CH3I clusters by nanosecond laser: Electron energy distribution and formation mechanism of multiply charged ions

Mass spectrometric and charge density studies of organometallic clusters photoionized by gigawatt laser pulses

“…Due to instrumental limitations we could not measure electron energies in the present study. Earlier, electron energy has been measured for different molecular clusters such as benzene (Zhang et al, 2009), diethyl ether (Zhang et al, 2010), methyl iodide (Zhao et al, 2012) and the mean electron energy lies in the range of 25-30 eV with maxima at 60-65 eV under similar experimental conditions (Table 5). Thus, electron energy distribution in case of TMS and TMT clusters is expected to be somewhat similar under the experimental conditions used during these studies.…”

“…This mechanism emphasized that resonantly excited intermediate vibronic energy levels play a dominant role in efficient coupling of laser energy with cluster medium. However, subsequent studies on low intensity Coulomb explosion of clusters revealed the presence of energetic electrons (Zhao et al, ) and an increase in charge state of atomic ions with increasing laser wavelength over a wide range spanning from visible to I.R. region of electromagnetic spectrum (Badani et al, ).…”

“…Hence the maximum electron energy, generated during this interaction process, is expected to be equal to or greater than the ionization energy (IE) of highest observed charge state. However, experimentally measured maximum electron energy for different cluster systems was significantly lower than energy required for generation of highest observed charge state (see Table ) (Sharma et al, ; Zhang et al, 2009, 2010; Zhao et al, ). Hence, in order to account for generation of high IE atomic species with low energy electrons, screening effects in clusters ought to be considered.…”

“…Thus, to explain this contrast photo-ionization behavior of clusters additional processes need to be considered. A three-stage cluster ionization mechanism has been proposed by Li and coworkers (Zhang et al, 2009(Zhang et al, , 2010Zhao et al, 2012) to explain different facets of the low laser intensity induced Coulomb explosion of clusters. This mechanism suggests that the primary step for generation of multiply charged atomic ions is the multiphoton ionization of the neutral cluster constituents (in this case TMS or TMT molecule).…”

Evidence for charge-induced dipole reaction in laser ionized van der Waals clusters: a case of Fe2+ reacting with argon atoms inside a cluster

“…This general trend in clusters has been rationalized on the basis of the three-stage cluster ionization mechanism. [18][19][20][21]32,33 According to this mechanism, ionization in a cluster is initiated via multiphoton absorption. The electrons generated due to ionization of atoms/molecules present on the cluster surface escape from the cluster immediately, thus leaving the cluster surface positively charged.…”