The angular distributions of fragment ions from labelled and unlabelled N2O in intense laser fields

The mass spectra and angular distributions of fragment ions arising from a Coulomb explosion of highly charged parent nitrous oxide ions, obtained in the femtosecond regime (~1016 W cm-2), are investigated. The N ion angular distributions from 14N2O show maxima when the laser polarization is parallel and orthogonal to the time-of-flight axis. Measurements with labelled molecules (15N-14N = 16O) indicate that the maxima arise from the peripheral and central N atoms in the molecular structure. The anisotropic distributions may be explained by assuming increased ionization and fragmentation when the molecular axis is parallel to the laser field. The bond angle prior to explosion is determined to be ~140°, irrespective of the charge state of the precursor, and calculations of the kinetic energies imparted to the fragment ions suggest that dissociation occurs at the equilibrium internuclear distance of the neutral molecule.

[1]  Chin,et al.  Dissociative tunnel ionization of H2 in an intense mid-ir laser field. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[2]  Cornaggia.  Large-amplitude nuclear motions in the laser-induced Coulomb explosion of carbon dioxide molecules. , 1996, Physical review. A, Atomic, molecular, and optical physics.

[3]  P. Corkum,et al.  Disentangling molecular alignment and enhanced ionization in intense laser fields , 1999 .

[4]  H. Loesch,et al.  Brute force in molecular reaction dynamics: A novel technique for measuring steric effects , 1990 .

[5]  P. Taday,et al.  GEOMETRY MODIFICATIONS AND ALIGNMENT OF H2O IN AN INTENSE FEMTOSECOND LASER PULSE , 1999 .

[6]  C. Maïnos.  Laser-induced steric effects in nonlinear processes from short laser pulses. , 1996 .

[7]  K. Yamanouchi,et al.  Mass-resolved two-dimensional momentum imaging of the Coulomb explosion of N2 and SO2 in an intense laser field , 1998 .

[8]  A. E. Kondo.  Laser-molecule Interactions And The Effects Of Permanent Dipoles , 1991 .

[9]  P. Taday,et al.  One and two-colour studies of the dissociative ionization and Coulomb explosion of with intense Ti:sapphire laser pulses , 1997 .

[10]  N. Nakashima,et al.  Coulomb explosion of benzene irradiated by an intense femtosecond laser pulse , 2000 .

[11]  S. L. Wang,et al.  Behavior of Polyatomic Molecules in Intense Infrared Laser Beams , 1998 .

[12]  P. Corkum,et al.  Observing molecular dynamics with timed Coulomb explosion imaging , 1998, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[13]  R. Levis,et al.  Calculating the Keldysh adiabaticity parameter for atomic, diatomic, and polyatomic molecules , 1998 .

[14]  C. Fotakis,et al.  LETTER TO THE EDITOR: Polarization effects on the ionization of molecules under picosecond and femtosecond laser excitation , 1999 .

[15]  G. Kumar,et al.  Pendular motion of linear in intense laser fields , 1996 .

[16]  P. Corkum,et al.  Subfemtosecond processes in strong laser fields. , 1997, Annual review of physical chemistry.

[17]  I. Mclaren,et al.  TIME-OF-FLIGHT MASS SPECTROMETER WITH IMPROVED RESOLUTION , 1955 .

[18]  P. Taday,et al.  Dynamic and geometric laser-induced alignment of molecules in intense laser fields , 1998 .

[19]  A. Bandrauk,et al.  Charge-resonance-enhanced ionization of molecular ions in intense laser pulses: Geometric and orientation effects , 1999 .

[20]  J. Loison,et al.  Molecular Axis Orientation by the "Brute Force" Method , 1995 .

[21]  Kumar,et al.  Molecular pendular states in intense laser fields. , 1996, Physical review. A, Atomic, molecular, and optical physics.

[22]  D. Mathur,et al.  Angle-resolved covariance mapping of spatially-aligned in an intense picosecond laser field , 1999 .

[23]  G. Kumar,et al.  Dynamic and geometric alignment of CS 2 in intense laser fields of picosecond and femtosecond duration , 1999, physics/9908059.

[24]  F. Stienkemeier,et al.  Steric effects in the state specific reaction Li+HF (v=1, j=1, m=0)→LiF+H , 1993 .

[25]  A. Giles,et al.  Field-ionization, Coulomb explosion of diatomic molecules in intense laser fields , 1996 .

[26]  Atsushi Iwamae,et al.  Coulomb explosion dynamics of N2 in intense laser field by mass-resolved momentum imaging , 1998 .

[27]  G. Kumar,et al.  Dissociation dynamics of in intense laser fields: directional specificity of and fragments , 1996 .

[28]  M. Vrakking,et al.  Coherent control of molecular orientation , 1997 .

[29]  P. Taday,et al.  Alignment and bending of by intense femtosecond laser pulses , 1998 .

[30]  Rost,et al.  Pendular states and spectra of oriented linear molecules. , 1992, Physical review letters.

[31]  K. Yamanouchi,et al.  Ultrafast structural deformation of NO2 in intense laser fields studied by mass-resolved momentum imaging , 1999 .

[32]  F. Salin,et al.  Changes in the geometry during the laser-induced multiple ionization and fragmentation , 1996 .

[33]  T. Auguste,et al.  Laser-matter interaction in intense laser fields , 1993 .

[34]  P. Taday,et al.  LETTER TO THE EDITOR: Double-pulse measurements of laser-induced alignment of molecules , 1998 .

[35]  R. P. Singhal,et al.  AN INVESTIGATION OF THE ANGULAR DISTRIBUTIONS OF FRAGMENT IONS ARISING FROM THE LINEAR CS2 AND CO2 MOLECULES , 1999 .

[36]  R. P. Singhal,et al.  A comparison of femtosecond and nanosecond multiphoton ionization and dissociation for some nitro-molecules , 1995 .

[37]  D. Mathur,et al.  An experimental and theoretical study of the dissociative ionization of and by an intense laser field , 1997 .

[38]  L. Frasinski,et al.  Covariance Mapping: A Correlation Method Applied to Multiphoton Multiple Ionization , 1989, Science.

[39]  A. Conjusteau,et al.  Dissociative ionization of H2 + in an intense laser field: Charge-resonance-enhanced ionization, Coulomb explosion, and harmonic generation at 600 nm. , 1996, Physical review. A, Atomic, molecular, and optical physics.

[40]  Luk,et al.  Isotopic studies of atomic site selectivity in molecular multiphoton ionization of N2O. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[41]  Miller Re,et al.  Spectroscopy of pendular states: The use of molecular complexes in achieving orientation. , 1992 .

[42]  Gerard Mourou,et al.  Compression of amplified chirped optical pulses , 1985 .

[43]  L. Frasinski,et al.  Multiphoton multiple ionisation of N2O probed by three-dimensional covariance mapping , 1991 .