Multiphoton ionization of the calcium atom by linearly and circularly polarized laser fields

Journal Article · Thu Apr 15 00:00:00 EDT 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.043418· OSTI ID:21408654

Buica, Gabriela; Nakajima, Takashi ^[1]

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1. Institute for Space Sciences, P.O. Box MG-23, 077125 Bucharest-Magurele (Romania)

We theoretically study multiphoton ionization of the Ca atom irradiated by the second (photon energy 3.1 eV) and third (photon energy 4.65 eV) harmonics of Ti:sapphire laser pulses (photon energy 1.55 eV). Because of the dense energy level structure the second and third harmonics of a Ti:sapphire laser are nearly single-photon resonant with the 4s4p {sup 1}P{sup o} and 4s5p {sup 1}P{sup o} states, respectively. Although two-photon ionization takes place through the near-resonant intermediate states with the same symmetry in both cases, it turns out that there are significant differences between them. The photoelectron energy spectra exhibit the absence or presence of substructures. More interestingly, the photoelectron angular distributions clearly show that the main contribution to the ionization processes by the third harmonic arises from the far-off-resonant 4s4p {sup 1}P{sup o} state rather than the near-resonant 4s5p {sup 1}P{sup o} state. These findings can be attributed to the fact that the dipole moment for the 4s{sup 2} {sup 1}S{sup e}-4s5p {sup 1}P{sup o} transition is much smaller than that for the 4s{sup 2} {sup 1}S{sup e}-4s4p {sup 1}P{sup o} transition.

• OSTI ID: 21408654
• Journal Information: Physical Review. A, Vol. 81, Issue 4; Other Information: DOI: 10.1103/PhysRevA.81.043418; (c) 2010 The American Physical Society; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
ATOMS
CALCIUM
DIPOLE MOMENTS
ENERGY LEVELS
ENERGY SPECTRA
EV RANGE
HARMONICS
INTERMEDIATE STATE
LASER RADIATION
LASERS
PHOTOIONIZATION
PHOTONS
PULSES
SAPPHIRE
SYMMETRY
ALKALINE EARTH METALS
BOSONS
CORUNDUM
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
IONIZATION
MASSLESS PARTICLES
METALS
MINERALS
OSCILLATIONS
OXIDE MINERALS
RADIATIONS
SPECTRA