Photons with One Colour

M. Protopapas, P. L. Knight

We examine the excitation dynamics of a model atom excited by a two-colour laser field. Here the two colours or frequencies are the fundamental and its third harmonic. The atomic model consists of two bound states which are near-resonantly coupled by a three-photon excitation by the fundamental and a one-photon excitation by the third harmonic, and a structureless continuum. We investigate how the laser parameters (intensity and frequency) and the relative phase between the two colours affects the degree of phase modulation in the ionization signal. We compare our findings from this simple model atom with those from more realistic atomic models by carrying out numerical integration of the hydrogenic Schrodinger equation in both one and three dimensions.

Patrick O’Keeffe, P. Bolognesi, Robert Richter +2 more

The one- and two-colour spectra of Neon Rydberg states have been recorded in the energy region below the first ionization threshold. Access to this region is achieved by recording the yield of Ne2+ ions formed in an associative ionization process between atoms in the Rydberg states formed in the photonic excitation and ground state neutral atoms. The one-colour spectra permit a study of the AI process as a function of the principal quantum number of the photo-excited Rydberg state while the two-colour spectra give access to Rydberg series previously unobserved using photon excitation.

M. Bertolotti

金昌泰, 梁秀清, 王成飞 +2 more

, at least three photons of wavelengths in visible region are required to ionize an uranium atom from its ground state or one of the low-lying metastable states. When a single-colour laser beam acts with the uranium vapor, the uranium atom can sequentially absorb three photons and ionize, but the cross sec-