The collisional angular-momentum mixing of $n=5\ensuremath{-}15$ Na $d$ states with the $l>2$ states of the same $n$ has been studied using He, Ne, and Ar as collision partners. At rare-gas pressures of \ensuremath{\sim}1 Torr, the $l\ensuremath{\ge}2$ states are thoroughly mixed and the mixture decays at the average radiative lifetime of all the $l\ensuremath{\ge}2$ states of the same $n$ . Using \ensuremath{\sim}1 Torr of neon to collisionally mix the $l\ensuremath{\ge}2$ states, the average lifetime for $l\ensuremath{\ge}2$ was measured for each $n$ and compared to the theoretical prediction for hydrogen, with which it is in excellent agreement. The cross section for $l$ mixing by each of the gases is found to increase sharply from $n=5 \mathrm{to} 10$ and decrease above $n=10$ . The magnitudes of the $l$ -mixing cross sections are found to correlate with the low-energy scattering lengths of the collision partners.The collisional angular-momentum mixing of $n=5\ensuremath{-}15$ Na $d$ states with the $l>2$ states of the same $n$ has been studied using He, Ne, and Ar as collision partners. At rare-gas pressures of \ensuremath{\sim}1 Torr, the $l\ensuremath{\ge}2$ states are thoroughly mixed and the mixture decays at the average radiative lifetime of all the $l\ensuremath{\ge}2$ states of the same $n$. Using \ensuremath{\sim}1 Torr of neon to collisionally mix the $l\ensuremath{\ge}2$ states, the average lifetime for $l\ensuremath{\ge}2$ was measured for each $n$ and compared to the theoretical prediction for hydrogen, with which it is in excellent agreement. The cross section for $l$ mixing by each of the gases is found to increase sharply from $n=5 \mathrm{to} 10$ and decrease above $n=10$. The magnitudes of the $l$-mixing cross sections are found to correlate with the low-energy scattering lengths of the collision partners.

Physical Review AMay 1, 1977144 citations

On calculation of collisional angular-momentum mixing of Rydberg states

J. Oreg, M. Strauss, G. Hazak

Jan 1, 19830 citations

Deexcitation of Rydberg states of He by He, Ne, Ar, Kr, and Xe

A. Hitachi, Christopher Davies, Terence A. King +2 more

The total quenching cross sections for $\mathrm{He}({n}^{1,3}S)(2\ensuremath{\le}n\ensuremath{\le}11)$ states by thermal collisions [600(+ 200, - 100) K] with He, Ne, Ar, Kr, and Xe have been measured. The main quenching mechanism is attributed to Penning ionization for lower $n$ , and collisional angular-momentum transfer for highly excited states. Measured cross sections are of the order of ${10}^{\ensuremath{-}15}$ to ${10}^{\ensuremath{-}14}$, ${\mathrm{cm}}^{2}$ . The values for higher $n$ states are much smaller than the geometrical cross section; this is explained by a relatively large energy spread between the $S$ state and $l\ensuremath{\ge}1$ states.The total quenching cross sections for $\mathrm{He}({n}^{1,3}S)(2\ensuremath{\le}n\ensuremath{\le}11)$ states by thermal collisions [600(+ 200, - 100) K] with He, Ne, Ar, Kr, and Xe have been measured. The main quenching mechanism is attributed to Penning ionization for lower $n$, and collisional angular-momentum transfer for highly excited states. Measured cross sections are of the order of ${10}^{\ensuremath{-}15}$ to ${10}^{\ensuremath{-}14}$, ${\mathrm{cm}}^{2}$. The values for higher $n$ states are much smaller than the geometrical cross section; this is explained by a relatively large energy spread between the $S$ state and $l\ensuremath{\ge}1$ states.

Physical Review ASep 1, 198024 citations

Collisional angular momentum mixing of f states of Na

Thomas F. Gallagher, William E. Cooke, S. A. Edelstein

In Na, the energy gap $\ensuremath{\Delta}E$ between the $n$ , $d$ state and the $n$ , $l>2$ states is ten times larger than $\ensuremath{\Delta}E$ between $n$ , $f$ and the $n$ , $l>3$ states. To investigate the effect of this difference on the $d$ - and $f$ -state $l$ -mixing cross sections, ${\ensuremath{\sigma}}_{d}$ and ${\ensuremath{\sigma}}_{f}$, we have recently carried out experiments to measure ${\ensuremath{\sigma}}_{d\ensuremath{-}f}$, the $l$ -mixing cross sections for a microwave-induced mixture of $d$ and $f$ states. Using the previously measured values of ${\ensuremath{\sigma}}_{d}$, we have derived values of ${\ensuremath{\sigma}}_{f}$ which have the same $n$ dependence as ${\ensuremath{\sigma}}_{d}$. ${\ensuremath{\sigma}}_{f}$ is larger than ${\ensuremath{\sigma}}_{d}$ for Ne, but smaller for He and Ar. In addition, we have analyzed the final states after one collision with Ar using selective field ionization of the $17l$ states and have observed that after one collision all the $l$ states are equally populated indicating that there are no $\ensuremath{\Delta}l$ selection rules for the process. This confirms the earlier suggestion that $l$ mixing is caused by a short-range interaction.In Na, the energy gap $\ensuremath{\Delta}E$ between the $n$, $d$ state and the $n$, $l>2$ states is ten times larger than $\ensuremath{\Delta}E$ between $n$, $f$ and the $n$, $l>3$ states. To investigate the effect of this difference on the $d$- and $f$-state $l$-mixing cross sections, ${\ensuremath{\sigma}}_{d}$ and ${\ensuremath{\sigma}}_{f}$, we have recently carried out experiments to measure ${\ensuremath{\sigma}}_{d\ensuremath{-}f}$, the $l$-mixing cross sections for a microwave-induced mixture of $d$ and $f$ states. Using the previously measured values of ${\ensuremath{\sigma}}_{d}$, we have derived values of ${\ensuremath{\sigma}}_{f}$ which have the same $n$ dependence as ${\ensuremath{\sigma}}_{d}$. ${\ensuremath{\sigma}}_{f}$ is larger than ${\ensuremath{\sigma}}_{d}$ for Ne, but smaller for He and Ar. In addition, we have analyzed the final states after one collision with Ar using selective field ionization of the $17l$ states and have observed that after one collision all the $l$ states are equally populated indicating that there are no $\ensuremath{\Delta}l$ selection rules for the process. This confirms the earlier suggestion that $l$ mixing is caused by a short-range interaction.

Physical Review AMar 1, 197859 citations

Collisional angular momentum transfer in rydberg states of helium

Robert S. Freund, Terry A. Miller, Bernard R. Zegarski +3 more

Chemical Physics LettersOct 1, 197713 citations

The collisional angular-momentum mixing of $n=5\ensuremath{-}15$ Na

d

states with the

l>2

states of the same

n

has been studied using He, Ne, and Ar as collision partners. At rare-gas pressures of \ensuremath{\sim}1 Torr, the $l\ensuremath{\ge}2$ states are thoroughly mixed and the mixture decays at the average radiative lifetime of all the $l\ensuremath{\ge}2$ states of the same

n

. Using \ensuremath{\sim}1 Torr of neon to collisionally mix the $l\ensuremath{\ge}2$ states, the average lifetime for $l\ensuremath{\ge}2$ was measured for each

n

and compared to the theoretical prediction for hydrogen, with which it is in excellent agreement. The cross section for

l

mixing by each of the gases is found to increase sharply from

n=5 \mathrm{to} 10

and decrease above

n=10

. The magnitudes of the

l

-mixing cross sections are found to correlate with the low-energy scattering lengths of the collision partners.

n

, and collisional angular-momentum transfer for highly excited states. Measured cross sections are of the order of ${10}^{\ensuremath{-}15}$ to ${10}^{\ensuremath{-}14}$,

{\mathrm{cm}}^{2}

. The values for higher

n

states are much smaller than the geometrical cross section; this is explained by a relatively large energy spread between the

S

state and $l\ensuremath{\ge}1$ states.

In Na, the energy gap $\ensuremath{\Delta}E$ between the

n

d

state and the

n

l>2

states is ten times larger than $\ensuremath{\Delta}E$ between

n

f

and the

n

l>3

states. To investigate the effect of this difference on the

d

- and

f

-state

l

-mixing cross sections, ${\ensuremath{\sigma}}_{d}$ and ${\ensuremath{\sigma}}_{f}$, we have recently carried out experiments to measure ${\ensuremath{\sigma}}_{d\ensuremath{-}f}$, the

l

-mixing cross sections for a microwave-induced mixture of

d

and

f

states. Using the previously measured values of ${\ensuremath{\sigma}}_{d}$, we have derived values of ${\ensuremath{\sigma}}_{f}$ which have the same

n

dependence as ${\ensuremath{\sigma}}_{d}$. ${\ensuremath{\sigma}}_{f}$ is larger than ${\ensuremath{\sigma}}_{d}$ for Ne, but smaller for He and Ar. In addition, we have analyzed the final states after one collision with Ar using selective field ionization of the

17l

states and have observed that after one collision all the

l

states are equally populated indicating that there are no $\ensuremath{\Delta}l$ selection rules for the process. This confirms the earlier suggestion that

l

mixing is caused by a short-range interaction.