The authors have studied the linear Stark effect of sodium Rydberg states by subDoppler high resolution spectroscopy using a continuous stepwise excitation of sodium atoms (3S to 3P to 3D to nF) with the help of a CW dye laser and of two single-mode diode lasers. They have shown a quasidegeneracy of m=0, mod m mod =1 and mod m mod =2 states, revealing an unexpected non-hydrogenic behaviour of Stark states in this linear regime. A simple model, based on a 'truncated Stark basis' approach accounts for this feature, which is common to all alkali atom Rydberg states.The authors have studied the linear Stark effect of sodium Rydberg states by subDoppler high resolution spectroscopy using a continuous stepwise excitation of sodium atoms (3S to 3P to 3D to nF) with the help of a CW dye laser and of two single-mode diode lasers. They have shown a quasidegeneracy of m=0, mod m mod =1 and mod m mod =2 states, revealing an unexpected non-hydrogenic behaviour of Stark states in this linear regime. A simple model, based on a 'truncated Stark basis' approach accounts for this feature, which is common to all alkali atom Rydberg states.

Journal of Physics B Atomic and Molecular PhysicsAug 28, 198429 citations

Field ionization of highly excited states of sodium

Thomas F. Gallagher, L. M. Humphrey, William E. Cooke +2 more

We have observed the selective ionization of the degenerate $|{m}_{j}|$ levels of $s$ , $p$ , and $d$ states of sodium in the range of $n$ from 15 to 20 and have shown that atoms produced in these low-field (\ensuremath{\sim} 10 V/cm) states pass adiabatically from low-field $|{m}_{j}|$ to intermediate-field $|{m}_{l}|$ states. Experiments on the Stark manifold states in intermediate fields (\ensuremath{\sim} 1 kV/cm) and high fields (\ensuremath{\sim} 4 kV/cm) show that the $|{m}_{l}|=0 \mathrm{and} 1$ states pass adiabatically from intermediate- to high-field states and that the passage of the $|{m}_{l}|=2$ states is very nearly adiabatic. These findings suggest a general approach for predicting the threshold fields for ionization of atomic Rydberg states.We have observed the selective ionization of the degenerate $|{m}_{j}|$ levels of $s$, $p$, and $d$ states of sodium in the range of $n$ from 15 to 20 and have shown that atoms produced in these low-field (\ensuremath{\sim} 10 V/cm) states pass adiabatically from low-field $|{m}_{j}|$ to intermediate-field $|{m}_{l}|$ states. Experiments on the Stark manifold states in intermediate fields (\ensuremath{\sim} 1 kV/cm) and high fields (\ensuremath{\sim} 4 kV/cm) show that the $|{m}_{l}|=0 \mathrm{and} 1$ states pass adiabatically from intermediate- to high-field states and that the passage of the $|{m}_{l}|=2$ states is very nearly adiabatic. These findings suggest a general approach for predicting the threshold fields for ionization of atomic Rydberg states.

Physical Review ASep 1, 1977186 citations

Selective Strong-Field Enhancement and Attenuation of Excitation and Ionization with Short Laser Pulses

N. A. Hart

The coherent control of atomic energy level population is important for several areas physics and engineering including fluorescent spectroscopy, resonantly enhanced multiphoton ionization, harmonic generation, remote sensing and lasing. At low intensities where the Stark shift can be neglected, coherent control mechanisms usually exploit resonances created from stationary energy states dressed by integer multiples of the photon energy. However, in the strong field limit where large laser pulse intensities lead to significant Stark shifts, the resonant conditions are dynamic both in time and space and will likely not be satisfied for the entire laser pulse or beam.\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. We also make a direct measurement of the ponderomotive shift of the continuum. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.\n\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.The coherent control of atomic energy level population is important for several areas physics and engineering including fluorescent spectroscopy, resonantly enhanced multiphoton ionization, harmonic generation, remote sensing and lasing. At low intensities where the Stark shift can be neglected, coherent control mechanisms usually exploit resonances created from stationary energy states dressed by integer multiples of the photon energy. However, in the strong field limit where large laser pulse intensities lead to significant Stark shifts, the resonant conditions are dynamic both in time and space and will likely not be satisfied for the entire laser pulse or beam.\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. We also make a direct measurement of the ponderomotive shift of the continuum. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.\n\n\nIn this research, we experimentally and theoretically demonstrate coherent control of atomic energy level population in sodium vapor as well as the selective excitation of sodium Rydberg levels using high intensity laser pulses. While techniques based on resonance interferences and rapid adiabatic passage have been introduced for selective excitation, the conditions that must be satisfied for these phenomena can be hampered by short femtosecond pulse durations and large Stark shifts. In contrast, a technique referred to here as Resonance Sampling, uses the AC Stark shifts to selectively induce Freeman resonances and is resilient to changes in the spectral phase. Freeman resonances established in this way can result in population inversion of the excited state, and may lead to new lasing mediums and remote sensing applications.

May 12, 20150 citations

Stark Ionization of Rydberg States

P. Jacquinot

Springer series in optical sciences/SPringer series in optical sciencesJan 1, 19791 citation

We have observed the selective ionization of the degenerate

|{m}_{j}|

levels of

s

p

, and

d

states of sodium in the range of

n

from 15 to 20 and have shown that atoms produced in these low-field (\ensuremath{\sim} 10 V/cm) states pass adiabatically from low-field

|{m}_{j}|

to intermediate-field

|{m}_{l}|

states. Experiments on the Stark manifold states in intermediate fields (\ensuremath{\sim} 1 kV/cm) and high fields (\ensuremath{\sim} 4 kV/cm) show that the

|{m}_{l}|=0 \mathrm{and} 1

states pass adiabatically from intermediate- to high-field states and that the passage of the

|{m}_{l}|=2

states is very nearly adiabatic. These findings suggest a general approach for predicting the threshold fields for ionization of atomic Rydberg states.