Time of flight emission spectroscopy of laser produced nickel plasma: Short-pulse and ultrafast excitations
- Laser and Nonlinear Optics Laboratory, Department of Physics, National Institute of Technology Calicut, Calicut 673601 (India)
- Ultrafast and Nonlinear Optics Lab, Light and Matter Physics Group, Raman Research Institute, Bangalore 560080 (India)
We report the experimental investigation and comparison of the temporal features of short-pulse (7 ns) and ultrafast (100 fs) laser produced plasmas generated from a solid nickel target, expanding into a nitrogen background. When the ambient pressure is varied in a large range of 10⁻⁶Torr to 10²Torr, the plume intensity is found to increase rapidly as the pressure crosses 1 Torr. Time of flight (TOF) spectroscopy of emission from neutral nickel (Ni I) at 361.9 nm (3d⁹(²D) 4p → 3d⁹(²D) 4s transition) reveals two peaks (fast and slow species) in short-pulse excitation and a single peak in ultrafast excitation. The fast and slow peaks represent recombined neutrals and un-ionized neutrals, respectively. TOF emission from singly ionized nickel (Ni II) studied using the 428.5 nm (3p⁶3d⁸(³P) 4s→ 3p⁶3d⁹ 4s) transition shows only a single peak for either excitation. Velocities of the neutral and ionic species are determined from TOF measurements carried out at different positions (i.e., at distances of 2 mm and 4 mm, respectively, from the target surface) on the plume axis. Measured velocities indicate acceleration of neutrals and ions, which is caused by the Coulomb pull of the electrons enveloping the plume front in the case of ultrafast excitation. Both Coulomb pull and laser-plasma interaction contribute to the acceleration in the case of short-pulse excitation. These investigations provide new information on the pressure dependent temporal behavior of nickel plasmas produced by short-pulse and ultrafast laser pulses, which have potential uses in applications such as pulsed laser deposition and laser-induced nanoparticle generation.
- OSTI ID:
- 22305683
- Journal Information:
- Journal of Applied Physics, Vol. 116, Issue 1; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
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