We have observed the phase dependence of microwave above-threshold ionization (ATI) of Rydberg potassium atoms at a microwave intensity of 3\ifmmode\times\else\texttimes\fi{} ${10}^{4}$ W ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. By using 5-ps pulses derived from a mode-locked tunable dye laser to create the initial Rydberg state, and phase locking the microwave field to a high harmonic of the mode-locking frequency, we are able to excite the atom at a specific phase of the microwave field. Measurement of the ejected electrons' energy as a function of the initial Rydberg state and the phase of the microwave field show that it is the phase of the field at which the electron becomes free of the atom that determines its kinetic energy. The energy dependence is described by a simple, classical theory that reveals the relationship between the so-called ``quiver'' and ``drift'' terms in the electron energy previously observed in ATI experiments at higher frequencies.We have observed the phase dependence of microwave above-threshold ionization (ATI) of Rydberg potassium atoms at a microwave intensity of 3\ifmmode\times\else\texttimes\fi{}${10}^{4}$ W ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. By using 5-ps pulses derived from a mode-locked tunable dye laser to create the initial Rydberg state, and phase locking the microwave field to a high harmonic of the mode-locking frequency, we are able to excite the atom at a specific phase of the microwave field. Measurement of the ejected electrons' energy as a function of the initial Rydberg state and the phase of the microwave field show that it is the phase of the field at which the electron becomes free of the atom that determines its kinetic energy. The energy dependence is described by a simple, classical theory that reveals the relationship between the so-called ``quiver'' and ``drift'' terms in the electron energy previously observed in ATI experiments at higher frequencies.

Physical Review ANov 1, 199013 citations

Phase-dependent energy transfer in a microwave field

K. Richard Overstreet, R. R. Jones, Thomas F. Gallagher

We have excited Li atoms to Rydberg states with a picosecond laser in the presence of a phase-locked microwave field. We have observed energy transfer to higher- and lower-lying Rydberg states depending on the phase of the microwave field at which the picosecond laser excitation occurs. These observations confirm the prediction of a classical picture of the energy transfer and demonstrate that the phase-dependent energy transfer is not limited to processes in which energy transfer occurs across the ionization limit.We have excited Li atoms to Rydberg states with a picosecond laser in the presence of a phase-locked microwave field. We have observed energy transfer to higher- and lower-lying Rydberg states depending on the phase of the microwave field at which the picosecond laser excitation occurs. These observations confirm the prediction of a classical picture of the energy transfer and demonstrate that the phase-dependent energy transfer is not limited to processes in which energy transfer occurs across the ionization limit.

Physical Review AMay 15, 20123 citations

Microwave Ionization of Rydberg Atoms

Leo Moorman, Peter M. Koch

WORLD SCIENTIFIC eBooksSep 1, 19923 citations

Microwave ionization of non-hydrogenic Rydberg atoms

H. Maeda, Thomas F. Gallagher

Bulletin of the American Physical SocietyMay 18, 20050 citations

We have observed the phase dependence of microwave above-threshold ionization (ATI) of Rydberg potassium atoms at a microwave intensity of 3\ifmmode\times\else\texttimes\fi{}

{10}^{4}

W ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. By using 5-ps pulses derived from a mode-locked tunable dye laser to create the initial Rydberg state, and phase locking the microwave field to a high harmonic of the mode-locking frequency, we are able to excite the atom at a specific phase of the microwave field. Measurement of the ejected electrons' energy as a function of the initial Rydberg state and the phase of the microwave field show that it is the phase of the field at which the electron becomes free of the atom that determines its kinetic energy. The energy dependence is described by a simple, classical theory that reveals the relationship between the so-called ``quiver'' and ``drift'' terms in the electron energy previously observed in ATI experiments at higher frequencies.