Multiphoton dissociation/ionization of CHCl<sub>3</sub> and CFCl<sub>3</sub> at 355 nm: an experimental and theoretical study

Sharma, Pramod K.; Vatsa, R.K.; Maity, Dilip Kumar; Kulshreshtha, S. K.

doi:10.1002/rcm.1638

Cited by 12 publications

(6 citation statements)

References 15 publications

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“…[10][11][12][13][14][15][16][17] Additionally, the above mechanism also provides logical explanation for the systematic evolution of charge state observed with increasing argon stagnation pressure as shown in Figure 2. Increasing the argon stagnation pressure results in an increase in the three body collision rate and hence the average size of the cluster.…”

Section: -11mentioning

confidence: 96%

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Interaction of nanosecond laser pulse with tetramethyl silane (Si(CH3)4) clusters: Generation of multiply charged silicon and carbon ions

et al. 2011

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Present work reports significantly high levels of ionization, eventually leading to Coulomb explosion of Tetramethyl silane (TMS) clusters, on interaction with laser pulses of intensity ∼10 9 W/cm 2 . Tetramethyl silane clusters, prepared by supersonic expansion were photoionized at 266, 355 or 532 nm and the resultant ions were detected using time-of-flight mass spectrometer. It is observed that wavelength of irradiation and the size of the cluster are crucial parameters which drastically affect the nature of charge species generated upon photoionization of cluster. The results show that clusters absorb significantly higher energy from the laser field at longer wavelengths (532 nm) and generate multiply charged silicon and carbon ions which have large kinetic energies. Further, laser-cluster interaction at different wavelengths has been quantified and charge densities at 266, 355 and 532 nm are found to be 4x 10 10 , 5x 10 10 and 5x 10 11 charges/cm 3 respectively. These unusual results have been rationalized based on dominance of secondary ionization processes at 532 nm ultimately leading to Coulomb explosion of clusters. In another set of experiments, multiply charged ions of Ar (up to +5 state) and Kr (up to +6 state) were observed when TMS doped inert gas clusters were photoionized at 532 and 355 nm. The extent of energy absorption at these two wavelengths is clearly manifested from the charge state of the atomic ions generated upon Coulomb disintegration of the doped cluster. These experiments thus demonstrate a novel method for generation of multiply charged atomic ions of inert gases at laser intensity of ∼ 10 9 W/cm 2 . The average size of the cluster exhibiting Coulomb explosion phenomena under giga watt intensity conditions has been estimated to be ∼ 6 nm. Experimental results obtained in the present work agree qualitatively with the model proposed earlier

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Section: -11mentioning

confidence: 96%

“…Details of the experimental setup have been described in our earlier publications [10][11][12][13][14][15][16][17] and only a brief account is given here. Neutral clusters were generated via supersonic expansion of TMS vapors seeded in helium/argon at a stagnation pressure of 1-6 bar, at room-temperature.…”

Section: Methodsmentioning

confidence: 99%

Interaction of nanosecond laser pulse with tetramethyl silane (Si(CH3)4) clusters: Generation of multiply charged silicon and carbon ions

et al. 2011

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“…Details of the experimental setup used for this study have been described in earlier publications 15, 16. The frequency doubled (532 nm), tripled (355 nm) and quadrupled (266 nm) output of a Nd:YAG laser (6–8 ns pulse width) was used for excitation and ionization.…”

Section: Methodsmentioning

confidence: 99%

Photoionization of CH₃I mediated by the C state in the visible and ultraviolet regions

Sharma

Vatsa

Rajasekhar

et al. 2005

Rapid Comm Mass Spectrometry

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Three/two-photon resonant multiphoton ionization (MPI) of the CH3I monomer has been studied in the gas phase at 532 and 355 nm using time-of-flight mass spectrometry. Under low laser intensity (approximately 10(9) W/cm2) the mass spectra showed peaks at m/z 15, 127 and 142, corresponding to [CH3]+, [I]+ and [CH3I]+ species, at both these wavelengths. The laser power dependence for [CH3I]+, [I]+ and [CH3]+ ions showed a three-photon dependence at 532 nm. For the same three ions, photoionization studies at 355 nm gave a power dependence of 2. Both these results suggest that a vibronic energy level at approximately 7 eV, lying in the Rydberg C state, acts as a resonant intermediate level in ionization of CH3I. In the case of 355 nm, with increasing intensity additional peaks at m/z 139 and 141 were observed which could be assigned to [CI]+ and [CH2I]+ fragments. In contrast, for high intensity radiation at 532 nm ( approximately 2 x 10(10) W/cm2), only the [CI]+ fragment was observed. At these wavelengths, fragment ions observed in mass spectra mainly arise from photodissociation of the parent ion. Experiments at another wavelength in the visible region (564.2 nm) confirmed the results obtained at 532 nm. In order to assess the role of the A state in these MPI experiments, additional experiments were performed at 266 and 282.1 nm, which access the A state directly via a one-photon transition, and showed absence of a surviving precursor ion. Reaction energies for various possible dissociation channels of CH3I/[CH3I]+/[CH2I]+ were calculated theoretically at the MP2 level using the GAMESS electronic structure program.

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“…249 They have also studied laser-induced photodissociation of acetone, CH 3 SCH 3 , CS 2 , CH 2 Cl 2 , CH 2 Br 2 , CHCl 3 and CFCl 3 using 355 nm and/or 532 nm lasers. [250][251][252][253] They demonstrated generation of excited multiply charged atomic ions of carbon (C m+ , m = 1-4) and sulfur (S n+ , n = 1-6) when a gigawatt laser-induced explosion in CS 2 clusters. 254 They have also developed a technique for charge-density measurements in laser-induced interactions.…”

Section: Chemical Physics and Physical Chemistrymentioning

confidence: 99%

Mass Spectrometry in India

Vairamani

Prabhakar

2012

Eur J Mass Spectrom (Chichester)

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All rights reserved EUROPEAN JOURNAL OF MASS SPECTROMETRY This review highlights the research in mass spectrometry carried out all over India, with a focus on the last two decades. There has been a phenomenal increase in the use of mass spectrometers in India during the last decade following the introduction, at the beginning of the 21st century, of rugged electrospray ionization sources for the commercially available instruments, with applications such as pharmacokinetics and bio-equivalence drug studies, pesticide residue analysis and proteomics. There have been more papers published in these areas than could be fully covered in this article. This review covers mostly research in mass spectrometry carried out continuously in institutions where advanced facilities for mass spectrometry are functional. Researchers in India, with some notable exceptions, have always used and still use commercial mass spectrometers in their various areas of research, rather than develop their unique instruments. The review is divided into three parts: organic, elemental (or atomic) and biological mass spectrometry. Organic mass spectrometry Organic and bio-organic chemistry Research in organic mass spectrometry in the early years was mainly focused on the study of mass spectral fragmentation of different classes of new compounds,and was initiated in the 1960s by the late Das and his colleagues from the National Chemical Laboratory (NCL), Pune. The first double-focusing mass spectrometer (CEC-110 B) was installed at NCL for high-resolution mass measurements. The compounds studied by Das and his colleagues included aromatic amides, Benzophenanthridine derivatives, norses

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Multiphoton dissociation/ionization of CHCl₃ and CFCl₃ at 355 nm: an experimental and theoretical study

Cited by 12 publications

References 15 publications

Interaction of nanosecond laser pulse with tetramethyl silane (Si(CH3)4) clusters: Generation of multiply charged silicon and carbon ions

Interaction of nanosecond laser pulse with tetramethyl silane (Si(CH3)4) clusters: Generation of multiply charged silicon and carbon ions

Photoionization of CH₃I mediated by the C state in the visible and ultraviolet regions

Mass Spectrometry in India

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Multiphoton dissociation/ionization of CHCl3 and CFCl3 at 355 nm: an experimental and theoretical study

Cited by 12 publications

References 15 publications

Interaction of nanosecond laser pulse with tetramethyl silane (Si(CH3)4) clusters: Generation of multiply charged silicon and carbon ions

Interaction of nanosecond laser pulse with tetramethyl silane (Si(CH3)4) clusters: Generation of multiply charged silicon and carbon ions

Photoionization of CH3I mediated by the C state in the visible and ultraviolet regions

Mass Spectrometry in India

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Multiphoton dissociation/ionization of CHCl₃ and CFCl₃ at 355 nm: an experimental and theoretical study

Photoionization of CH₃I mediated by the C state in the visible and ultraviolet regions