Dynamic and geometric laser-induced alignment of molecules in intense laser fields

Posthumus, Jan; Plumridge, J.; Thomas, M K; Codling, K.; Frasinski, L. J.; Langley, A. J.; Taday, Philip F.

doi:10.1088/0953-4075/31/13/002

Cited by 144 publications

(138 citation statements)

References 16 publications

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“…Consequently, the molecule ionizes predominantly at R ≈ R C . The fragment ions born out of such a CE usually give rise to an anisotropic angular distribution which favors the direction of the polarization vector of the laser field [18,[25][26][27][28][29][30][31][32][33][34]. Such anisotropic angular distributions are characteristic for a CE based on a dynamic or a geometric alignment mechanism or on a combination of these two.…”

Section: Introductionmentioning

confidence: 99%

“…The interaction between this induced dipole moment and the E-field amplitude of the laser field pre-aligns the parent molecular axis to the laser's Efield amplitude until the molecular bond stabilizes. Subsequently a Coulomb Explosion occurs after which the ionic fragments recoil direction is parallel to the E-field amplitude of the laser pulse [18,[25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

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Dissociative ionization and Coulomb explosion of CH3I in intense femto second laser fields

Zhang

Luo

et al. 2017

Eur. Phys. J. D

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Abstract. The interaction of CH3I molecules with 100 fs 800 nm linearly polarized laser fields has been investigated at the intensity region from 2.6 × 10 14 to 5.8 × 10 14 W/cm 2 by means of a velocity map imaging method. The kinetic energy distribution of the various atomic fragment ions I q+ (q = 1−3) has been measured and reproduced by a fit of multiple Gaussian functions. Several dissociative ionization and Coulomb explosion channels were identified for I q+ (q = 1−3). As expected for a geometric alignment dominated interaction process the anisotropic angular recoil distributions of the atomic ion fragments are peaked in the laser polarization direction. The kinetic energy release (KER) of I q+ (q = 1−3) depending upon the laser intensity has been investigated. The relative weight of the various contributions from the identified dissociative ionization (DI) and Coulomb explosion (CE) channels is found to depend strongly on the laser intensity.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dissociative ionization and Coulomb explosion of CH3I in intense femto second laser fields

Zhang

Luo

et al. 2017

Eur. Phys. J. D

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“…The work of Tzallas et al [17] provides further evidence that ring opening, induced by strong laser fields, is possible. It therefore seems reasonable to assume that the abovementioned channels are plausible candidates based on the split structure observed in the 70 and 80 m/z range, and the indication in the momentum scaled mass spectrum of NB that the high mass fragments have release momenta consistent with H A number of polarization dependent studies of molecular ionization in the tunnel regime indicate that the ion peak shape is dependent on the amount of geometric or dynamic alignment experienced by the molecule [9,10,12,[45][46][47][48][49][50][51][52]. They generally find suppression of ionization when the polarization is circular, and enhancements of ionization in cases where the polarization is linear, with the CE component emphasized when the laser polarization is collinear with the time-of-flight spectrometer axis.…”

mentioning

confidence: 99%

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

Mullen

Coggiola

Oser

2009

J. Am. Soc. Mass Spectrom.

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The ultrafast laser-induced photoionization and photodissociation processes of the nitroaromatic containing explosive and explosive related compounds (ERCs) nitrobenzene (NB), 1,3-dinitrobenzene (DNB), m-nitrotoluene (MNT), 2,4-dinitrotoluene (DNT), and 2,4,6-trinitrotoluene (TNT) have been investigated at three laser wavelengths and power densities using a time-of-flight mass spectrometer. Examination of the mass spectra of these compounds reveals the enhanced formation of the molecular ion [M ϩ ] when ultraviolet (332 nm) and visible (495 nm) light is used relative to infrared (795 nm) radiation. In addition, at 795 nm and a power density of 3.5 ϫ 10 14 W/cm 2 , the presence of a competition between multiphoton ionization (MPI) and Coulomb explosion (CE) channels is revealed by peak shape analysis, and is thought to be operative under these conditions for all of the molecules investigated. [5][6][7][8][9][10][11][12], and polyatomic aromatic organic molecules [13][14][15][16][17][18][19][20][21][22][23], has been the subject of intense investigation. These studies have focused on the fundamental interaction of the laser pulse with the atomic or molecular system, and have generally found a number of operative ionization and dissociation mechanisms present, which are sensitive to the laser wavelength and power density. In addition, a number of studies have also been dedicated to the investigation of the analytical usefulness of femtosecond laser ionization toward molecular specific detection. A prime example is the application to the ionization and detection of the explosives and explosives related compounds pioneered by . Their studies focused on an understanding of the mass spectra obtained using ultrafast laser pulses in conjunction with time-of-flight mass spectrometry, M ϩ ion formation, and specific molecular fragments that could be assigned to a particular precursor species. Of particular interest was the demonstration of isomer dependent mass spectra for the three isomers of nitrotoluene.The motivation to apply femtosecond laser ionization to the study of explosives and ERCs originated from previous laser ionization work, which found that nanosecond laser ionization in the ultraviolet led to extensive molecular fragmentation [31][32][33][34][35][36]. The extensive fragmentation was determined to be non-useful for species-specific identification, even though abundant NO ϩ ions were observed in the mass spectra [37]. The presence of NO ϩ in the mass spectra of these species naturally raised questions regarding its formation. Mechanistically, it was discovered that the dissociative lifetimes of the intermediate states involved in the ionization process were about a few hundred femtoseconds, and that this rapid dissociation led to the extensive fragmentation observed in the mass spectra. Further, the presence of NO ϩ in the mass spectra of these species was attributed to rapid dissociation of the parent molecule (RNO 2 ) producing the NO 2 fragment. The NO 2 molecule undergoes an additional photon absorptio...

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“…The amount of depletion is a measure of the laser-induced alignment. Using this method, Posthumus et al [26,27] concluded that dynamic alignment dominated for H 2 and geometric alignment dominated for I 2 under a 50 fs laser field.…”

mentioning

confidence: 99%

Dynamic alignment of C₂H₄ investigated by using two linearly polarized femtosecond laser pulses

et al. 2006

J. Am. Soc. Mass Spectrom.

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Dynamic and geometric laser-induced alignment of molecules in intense laser fields

Cited by 144 publications

References 16 publications

Dissociative ionization and Coulomb explosion of CH3I in intense femto second laser fields

Dissociative ionization and Coulomb explosion of CH3I in intense femto second laser fields

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

Dynamic alignment of C₂H₄ investigated by using two linearly polarized femtosecond laser pulses

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Dynamic and geometric laser-induced alignment of molecules in intense laser fields

Cited by 144 publications

References 16 publications

Dissociative ionization and Coulomb explosion of CH3I in intense femto second laser fields

Dissociative ionization and Coulomb explosion of CH3I in intense femto second laser fields

Femtosecond laser photoionization time-of-flight mass spectrometry of nitro-aromatic explosives and explosives related compounds

Dynamic alignment of C2H4 investigated by using two linearly polarized femtosecond laser pulses

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Dynamic alignment of C₂H₄ investigated by using two linearly polarized femtosecond laser pulses