Physical Review Letters

Stark Ionization of High-Lying States of Sodium

Theodore W. Ducas, Michael G. Littman, Richard R. Freeman, Daniel Kleppner

Published Aug 11, 1975• 201 citations

Abstract

By using stepwise excitation in an atomic beam, we have excited slow-moving atoms to pure high-lying quantum states at densities low enough to avoid loss by collision. The atoms were detected with high efficiency by Stark ionization. Results are presented of a study of the threshold field for ionization for $s$ states of sodium with principal quantum number $n$ from 26 to 37.

DOI: 10.1103/physrevlett.35.366

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Physical Review Letters

Stark Ionization of High-Lying States of Sodium

Theodore W. Ducas, Michael G. Littman, Richard R. Freeman, Daniel Kleppner

Published Aug 11, 1975• 201 citations

Publisher

Abstract

s

states of sodium with principal quantum number

n

from 26 to 37.

DOI: 10.1103/physrevlett.35.366

Related papers

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

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Journal of Physics B Atomic and Molecular PhysicsApr 28, 197937 citations

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Ting S. Luk, Louis F. DiMauro, T. H. Bergeman +1 more

We observed well-resolved spectral features in the stepwise ionization of Na in an applied electric field near the zero-field ionization threshold. A 5890-A pulse excites atoms to the $3^{2}P$ state and a~4085-A pulse, swept through threshold ionizes them. Using the method of Luc-Koenig, we calculated the oscillator strength density versus blue laser frequency and compared it with our data. The agreement is excellent. Parabolic quantum numbers have been assigned to the spectrum and the Fano profiles have been analyzed.We observed well-resolved spectral features in the stepwise ionization of Na in an applied electric field near the zero-field ionization threshold. A 5890-A pulse excites atoms to the $3^{2}P$ state and a~4085-A pulse, swept through threshold ionizes them. Using the method of Luc-Koenig, we calculated the oscillator strength density versus blue laser frequency and compared it with our data. The agreement is excellent. Parabolic quantum numbers have been assigned to the spectrum and the Fano profiles have been analyzed.

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P. Pillet, H. B. van Linden van den Heuvell, W. W. Smith +3 more

Electric field ionization of excited Na atoms by microwave fields between 12 and 15 GHz exhibits several interesting phenomena. The $|m|=0 \mathrm{and} 1$ states may be ionized with a very low microwave field, $\ensuremath{\sim}\frac{1}{{3n}^{5}}$, corresponding to the point at which the $n$ and $n+1$ Stark manifolds of principal quantum numbers $n$ and $n+1$ intersect. The ionization occurs by an atom's making a succession of Landau-Zener transitions to higher-lying states, finally reaching the classical ionization limit. The $|m|=2$ states, on the other hand, ionize at a very high microwave field, $\ensuremath{\sim}\frac{1}{{9n}^{4}}$. Both these observations and the more familiar static or low-frequency result of ionization by a field of $\ensuremath{\sim}\frac{1}{{16n}^{4}}$ are all consistent with ionization in a completely classical fashion. The apparent differences are due to the dynamics of passing from zero field to a high ionizing field.Electric field ionization of excited Na atoms by microwave fields between 12 and 15 GHz exhibits several interesting phenomena. The $|m|=0 \mathrm{and} 1$ states may be ionized with a very low microwave field, $\ensuremath{\sim}\frac{1}{{3n}^{5}}$, corresponding to the point at which the $n$ and $n+1$ Stark manifolds of principal quantum numbers $n$ and $n+1$ intersect. The ionization occurs by an atom's making a succession of Landau-Zener transitions to higher-lying states, finally reaching the classical ionization limit. The $|m|=2$ states, on the other hand, ionize at a very high microwave field, $\ensuremath{\sim}\frac{1}{{9n}^{4}}$. Both these observations and the more familiar static or low-frequency result of ionization by a field of $\ensuremath{\sim}\frac{1}{{16n}^{4}}$ are all consistent with ionization in a completely classical fashion. The apparent differences are due to the dynamics of passing from zero field to a high ionizing field.

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Ionization of Na atoms by 8-GHz electric fields

H. B. van Linden van den Heuvell, Thomas F. Gallagher

The ionization of Na atoms by 8-GHz electric fields from principal quantum number n=16--42 exhibits a threshold for the \ensuremath{\Vert}m\ensuremath{\Vert}=0 and 1 states of E\ensuremath{\approxeq}1/3 ${n}^{5}$ , and two thresholds for the \ensuremath{\Vert}m\ensuremath{\Vert}=2 states of E\ensuremath{\approxeq}1/9 ${n}^{4}$ and E\ensuremath{\approxeq}1/21 ${n}^{4}$ depending upon the n state. The \ensuremath{\Vert}m\ensuremath{\Vert}=0 and 1 thresholds show a departure from a 1/ ${n}^{5}$ scaling at high n which we interpret as being due to the fact that the relatively slower atomic frequencies at high n no longer match the 8 GHz microwave frequency. The E=1/21 ${n}^{4}$ \ensuremath{\Vert}m\ensuremath{\Vert}=2 threshold has not to our knowledge been observed before, and we interpret it as arising from the ionization of the highest energy, or blue, Stark state at the classical limit for ionization.The ionization of Na atoms by 8-GHz electric fields from principal quantum number n=16--42 exhibits a threshold for the \ensuremath{\Vert}m\ensuremath{\Vert}=0 and 1 states of E\ensuremath{\approxeq}1/3${n}^{5}$, and two thresholds for the \ensuremath{\Vert}m\ensuremath{\Vert}=2 states of E\ensuremath{\approxeq}1/9${n}^{4}$ and E\ensuremath{\approxeq}1/21${n}^{4}$ depending upon the n state. The \ensuremath{\Vert}m\ensuremath{\Vert}=0 and 1 thresholds show a departure from a 1/${n}^{5}$ scaling at high n which we interpret as being due to the fact that the relatively slower atomic frequencies at high n no longer match the 8 GHz microwave frequency. The E=1/21${n}^{4}$ \ensuremath{\Vert}m\ensuremath{\Vert}=2 threshold has not to our knowledge been observed before, and we interpret it as arising from the ionization of the highest energy, or blue, Stark state at the classical limit for ionization.

Physical Review ASep 1, 198520 citations

s

states of sodium with principal quantum number

n

from 26 to 37.

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 observed well-resolved spectral features in the stepwise ionization of Na in an applied electric field near the zero-field ionization threshold. A 5890-A pulse excites atoms to the

3^{2}P

state and a~4085-A pulse, swept through threshold ionizes them. Using the method of Luc-Koenig, we calculated the oscillator strength density versus blue laser frequency and compared it with our data. The agreement is excellent. Parabolic quantum numbers have been assigned to the spectrum and the Fano profiles have been analyzed.

Electric field ionization of excited Na atoms by microwave fields between 12 and 15 GHz exhibits several interesting phenomena. The

|m|=0 \mathrm{and} 1

states may be ionized with a very low microwave field, $\ensuremath{\sim}\frac{1}{{3n}^{5}}$, corresponding to the point at which the

n

and

n+1

Stark manifolds of principal quantum numbers

n

and

n+1

intersect. The ionization occurs by an atom's making a succession of Landau-Zener transitions to higher-lying states, finally reaching the classical ionization limit. The

|m|=2

states, on the other hand, ionize at a very high microwave field, $\ensuremath{\sim}\frac{1}{{9n}^{4}}$. Both these observations and the more familiar static or low-frequency result of ionization by a field of $\ensuremath{\sim}\frac{1}{{16n}^{4}}$ are all consistent with ionization in a completely classical fashion. The apparent differences are due to the dynamics of passing from zero field to a high ionizing field.

{n}^{5}

, and two thresholds for the \ensuremath{\Vert}m\ensuremath{\Vert}=2 states of E\ensuremath{\approxeq}1/9

{n}^{4}

and E\ensuremath{\approxeq}1/21

{n}^{4}

depending upon the n state. The \ensuremath{\Vert}m\ensuremath{\Vert}=0 and 1 thresholds show a departure from a 1/

{n}^{5}

scaling at high n which we interpret as being due to the fact that the relatively slower atomic frequencies at high n no longer match the 8 GHz microwave frequency. The E=1/21

{n}^{4}

\ensuremath{\Vert}m\ensuremath{\Vert}=2 threshold has not to our knowledge been observed before, and we interpret it as arising from the ionization of the highest energy, or blue, Stark state at the classical limit for ionization.