We have investigated multiphoton ionization of Ba $6snl$ Rydberg states by intense 200-fs laser pulses. Specifically, we have excited Ba atoms to the $6sns$ and $6snd$ 15\ensuremath{\infty} states using two nanosecond lasers. The atoms were then irradiated with the fs pulses produced by a mode-locked, regeneratively amplified Ti:sapphire laser that is stepwise-tunable between 790 and 850 nm. We have used both the fundamental light and the second harmonic (395--425 nm) to investigate the ionization dynamics in these two wavelength regions. In contrast to previous experiments, in which laser pulses 5 ps or longer were used, our results indicate that excitation of ${\mathrm{Ba}}^{+}$ Rydberg states and ${\mathrm{Ba}}^{2+}$ photoions is relatively insensitive to the femtosecond laser wavelength. In addition, we find that, as the Kepler orbital period of the Ba Rydberg electron becomes comparable to this very small laser pulse width, the inner electron ionization process no longer appears to be instantaneous to the outer electron, and the outer electron is not projected onto ${\mathrm{Ba}}^{+}$ Rydberg states.We have investigated multiphoton ionization of Ba $6snl$ Rydberg states by intense 200-fs laser pulses. Specifically, we have excited Ba atoms to the $6sns$ and $6snd$ 15\ensuremath{\infty} states using two nanosecond lasers. The atoms were then irradiated with the fs pulses produced by a mode-locked, regeneratively amplified Ti:sapphire laser that is stepwise-tunable between 790 and 850 nm. We have used both the fundamental light and the second harmonic (395--425 nm) to investigate the ionization dynamics in these two wavelength regions. In contrast to previous experiments, in which laser pulses 5 ps or longer were used, our results indicate that excitation of ${\mathrm{Ba}}^{+}$ Rydberg states and ${\mathrm{Ba}}^{2+}$ photoions is relatively insensitive to the femtosecond laser wavelength. In addition, we find that, as the Kepler orbital period of the Ba Rydberg electron becomes comparable to this very small laser pulse width, the inner electron ionization process no longer appears to be instantaneous to the outer electron, and the outer electron is not projected onto ${\mathrm{Ba}}^{+}$ Rydberg states.

Physical Review AOct 1, 19985 citations

Rydberg atom spectroscopy (A)

S. Haroche

Journal of the Optical Society of America AMay 1, 19780 citations

Near-Threshold Laser Spectroscopy of Rydberg and Autoionization States of Thallium Atom

N. B. Éshkobilov, Sh. R. Haidarov, A. S. Kurbaniyazov

Journal of Applied SpectroscopyNov 1, 20250 citations

High-Resolution Electron Spectroscopy of Laser-Excited Ba Rydberg Atoms

Herbert H. Rinneberg, Jörg Neukammer, U. Majewski +1 more

The ionization of $6sns^{1}S_{0}$ Rydberg states of $^{138}\mathrm{Ba}$ has been investigated by high-resolution electron spectroscopy. The Rydberg states were excited by two cw dye lasers via the $6s6p^{1}P_{1}$ level. The electron spectra show rich structure between 0.025 and 3 eV, largely attributable to collisional (Penning) ionization, photoionization, and autoionizing transitions. The first process might be interpreted as superelastic scattering of the Rydberg electron by optically pumped $\mathrm{Ba}(6s6p^{1}P_{1})$ or $\mathrm{Ba}(6s5d^{1}D_{2})$ atoms.The ionization of $6sns^{1}S_{0}$ Rydberg states of $^{138}\mathrm{Ba}$ has been investigated by high-resolution electron spectroscopy. The Rydberg states were excited by two cw dye lasers via the $6s6p^{1}P_{1}$ level. The electron spectra show rich structure between 0.025 and 3 eV, largely attributable to collisional (Penning) ionization, photoionization, and autoionizing transitions. The first process might be interpreted as superelastic scattering of the Rydberg electron by optically pumped $\mathrm{Ba}(6s6p^{1}P_{1})$ or $\mathrm{Ba}(6s5d^{1}D_{2})$ atoms.

Physical Review LettersOct 24, 198315 citations

The Multi-Photon Induced Fano Effect

K. L. Litvinenko

The ordinary Fano effect occurs in many-electron atoms and requires an auto-ionizing state.With such a state, photo-ionization may proceed via pathways that interfere, and the characteristicasymmetric resonance structures appear in the continuum. Here we demonstrate that Fano structure15may also be induced without need of auto-ionization, by dressing the continuum with an ordinarybound state in any atom by a coupling laser. Using multi-photon processes gives complete, ultra-fastcontrol over the interference. We show that a line-shape indexqnear unity (maximum asymmetry)may be produced in hydrogenic silicon donors with a relatively a weak beam. Since the Fanolineshape has both constructive and destructive interference, the laser control opens the possibility20of state-selective detection with enhancement on one side of resonance and invisibility on the other.We discuss a variety of atomic and molecular spectroscopies, and in the case of silicon donors weprovide a calculation for a qubit readout applicationThe ordinary Fano effect occurs in many-electron atoms and requires an auto-ionizing state.With such a state, photo-ionization may proceed via pathways that interfere, and the characteristicasymmetric resonance structures appear in the continuum. Here we demonstrate that Fano structure15may also be induced without need of auto-ionization, by dressing the continuum with an ordinarybound state in any atom by a coupling laser. Using multi-photon processes gives complete, ultra-fastcontrol over the interference. We show that a line-shape indexqnear unity (maximum asymmetry)may be produced in hydrogenic silicon donors with a relatively a weak beam. Since the Fanolineshape has both constructive and destructive interference, the laser control opens the possibility20of state-selective detection with enhancement on one side of resonance and invisibility on the other.We discuss a variety of atomic and molecular spectroscopies, and in the case of silicon donors weprovide a calculation for a qubit readout application

Sep 12, 20190 citations

We have investigated multiphoton ionization of Ba

6snl

Rydberg states by intense 200-fs laser pulses. Specifically, we have excited Ba atoms to the

6sns

and

6snd

15\ensuremath{\infty} states using two nanosecond lasers. The atoms were then irradiated with the fs pulses produced by a mode-locked, regeneratively amplified Ti:sapphire laser that is stepwise-tunable between 790 and 850 nm. We have used both the fundamental light and the second harmonic (395--425 nm) to investigate the ionization dynamics in these two wavelength regions. In contrast to previous experiments, in which laser pulses 5 ps or longer were used, our results indicate that excitation of

{\mathrm{Ba}}^{+}

Rydberg states and

{\mathrm{Ba}}^{2+}

photoions is relatively insensitive to the femtosecond laser wavelength. In addition, we find that, as the Kepler orbital period of the Ba Rydberg electron becomes comparable to this very small laser pulse width, the inner electron ionization process no longer appears to be instantaneous to the outer electron, and the outer electron is not projected onto

{\mathrm{Ba}}^{+}

Rydberg states.

The ionization of

6sns^{1}S_{0}

Rydberg states of

^{138}\mathrm{Ba}

has been investigated by high-resolution electron spectroscopy. The Rydberg states were excited by two cw dye lasers via the

6s6p^{1}P_{1}

level. The electron spectra show rich structure between 0.025 and 3 eV, largely attributable to collisional (Penning) ionization, photoionization, and autoionizing transitions. The first process might be interpreted as superelastic scattering of the Rydberg electron by optically pumped

\mathrm{Ba}(6s6p^{1}P_{1})

\mathrm{Ba}(6s5d^{1}D_{2})

atoms.