Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

Level-Crossing Spectroscopy in 7S2 Thallium. I. Studies of Coherence-Narrowing, Collision-Broadening, and Buffer-Gas Effects

Jin-Yuan Hsieh, James C. Baird

Published Jul 1, 1972• 28 citations
Publisher

Abstract

The lifetime, coherence narrowing, and collision broadening of the $7^{2}S_{\frac{1}{2}}$ excited state of atomic thallium has been studied by the technique of zero-field level-crossing spectroscopy. The lifetime of the $7^{2}S_{\frac{1}{2}}$ state is determined to be 7.55 (0.08) nsec. The full coherence-narrowing effect gave a branching ratio, from $F=0$ of $7^{2}S_{\frac{1}{2}}$ to the ground state, of 43%. The cross section for thallium-thallium resonance-broadening collisions is ${\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{T}\mathrm{l}}=\frac{5.38(0.49)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}}{\overline{v}}$ ${\mathrm{cm}}^{2}$. The effect of 426-torr helium on the thallium lifetime, coherence narrowing, and resonance broadening was also investigated. From the low-thallium-density region the cross section for helium depolarization of the thallium $7^{2}S$ state is ${\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{H}\mathrm{e}}\ensuremath{\cong}\frac{7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}}{\overline{v}}$ ${\mathrm{cm}}^{2}$. There is also indication of a buildup of population in the metastable $6^{2}P_{\frac{3}{2}}$ thallium state. From the data, the cross section for the process $\mathrm{Tl}(6^{2}P_{\frac{3}{2}})\ensuremath{\rightarrow}\mathrm{Tl}(6^{2}P_{\frac{1}{2}})$ by helium collisions is $\ensuremath{\sigma}\ensuremath{\simeq}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}21}$ ${\mathrm{cm}}^{2}$. The Tl branching ratio in the presence of helium is 39%. It was also found that the thallium-thallium resonance-broadening cross section is ${\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{T}\mathrm{l}}=\frac{4.04(0.32)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}}{\overline{v}}$ ${\mathrm{cm}}^{2}$ in the presence of 426 torr of helium. In the presence of 113 torr of He, the resonance-broadening cross section was found to be ${\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{T}\mathrm{l}}=\frac{5.22(0.13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}}{\overline{v}}$ ${\mathrm{cm}}^{2}$. In the case of Ar as the buffer gas, ${\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{A}\mathrm{r}}=\frac{8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}}{\overline{v}}$ ${\mathrm{cm}}^{2}$.

DOI
10.1103/physreva.6.141

Related papers

Studies of Coherence Narrowing and Resonance Broadening and Effects of Rare Gas on these Phenomena by Zero-Field Level Crossing Spectroscopy in the 7S-STATE of Thallium.

Ching-Chiang . Hsieh

•Jan 1, 1970•0 citations

Level-Crossing Spectroscopy in 7S122 Thallium. II. Theory of Self-Broadening and Tl*-Tl—Foreign-Gas Collisions

A. Omont, Jin-Yuan Hsieh, James C. Baird

The experimental results for the self-broadening of pure Tl of the previous paper are shown to be in good agreement with the theory of resonant collisions, taking into account the effects of the hyperfine structure. Wall collisions are nearly negligible in that case. The decrease of the self-broadening observed with the addition of a foreign gas is explained in terms of three-body collisions (Tl-He collisions occurring during a Tl*-Tl collision) which broaden the optical transitions of Tl and decrease the resonance effect in the transfer of excitation between Tl atoms. The quantitative agreement obtained with the experimental results shows that these three-body collisions must be responsible for the major part of the observed reduction in self-broadening.

Physical Review A•Jul 1, 1972•7 citations

Lifetime, Coherence Narrowing, and Hyperfine Structure of the (6s26p7s) P1∘3 State in Lead

E. B. Saloman, W. Happer

The lifetime and hyperfine structure of the $(6{s}^{2}6p7s) ^{3}{P}_{1}^{\ensuremath{\circ}}$ excited state in lead have been investigated by the technique of level-crossing spectroscopy. The lifetime of the state was determined to be $\ensuremath{\tau}=5.75(20)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec. The linewidth of the level-crossing signal was observed to saturate at a "coherence-narrowed" value in agreement with theoretical predictions. The magnitude of this narrowing corresponds to a 27(3)% branching ratio to the ground state. When the branching ratio and the lifetime are combined with the $f(3639 \mathrm{\AA{}}):f(4058 \mathrm{\AA{}})$ oscillator-strength ratio measured by Khokhlov, one may infer the absolute $f$ values: $f(2833 \mathrm{\AA{}})=0.169(17)$, $f(3639 \mathrm{\AA{}})=0.040(8)$, $f(4058 \mathrm{\AA{}})=0.155(31)$. The high-field level crossing in the hyperfine structure of the first $^{3}{P}_{1}^{\ensuremath{\circ}}$ state of ${\mathrm{Pb}}^{207}$ was found to occur at a magnetic field ${H}_{c}=4661.1(4)$ G, which corresponds to a magnetic-dipole-interaction constant $A=8.811(17)\ifmmode\times\else\texttimes\fi{}{10}^{9}$ cps.

Physical Review•Apr 8, 1966•85 citations

Lifetime of the 2P11 and 3P11 States of Atomic Helium

James M. Burger, Allen Lurio

The radiative lifetime of the $2^{1}P_{1}$ and $3^{1}P_{1}$ state of atomic helium has been measured by the level-crossing technique. In the experiment, a beam of $2^{1}S_{0}$ metastable atoms was first produced and then excited to the $2^{1}P_{1}$ or $3^{1}P_{1}$ state with resonance radiation. The lifetimes were measured by observing the zero-field level-crossing signals in the detected 584- or 537-\AA{} fluorescent radiation when these $^{1}P_{1}$ states decayed to the $1^{1}S_{0}$ ground state. The results are $\ensuremath{\tau} (2^{1}P_{1})=(5.57\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec and $\ensuremath{\tau} (3^{1}P_{1})=(1.73\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec. These values are in excellent agreement with theory.

Physical Review A•Jan 1, 1971•21 citations

Collision-Induced Mixing in the 2P3 Levels of Helium

L. D. Schearer

The cross section for the transfer of excitation from the $2^{3}P_{0}$ level of helium to the $2^{3}P_{1}$ and $2^{3}P_{2}$ levels as a result of collisions with the ground-state helium atom ($1^{1}S_{0}$) has been measured with a conventional resonance-fluorescence technique. A ${\mathrm{He}}^{4}$ source excited the $2^{3}S_{1}\ensuremath{-}2^{3}P_{0}$ transition in a ${\mathrm{He}}^{3}$ absorption cell. The scattered light was examined with a high-resolution grating spectrometer and the ratio of the $2^{3}P_{0}\ensuremath{\rightarrow}2^{3}S_{1}$ to the $2^{3}P_{1,2}\ensuremath{\rightarrow}2^{3}S_{1}$ intensities was measured as a function of cell pressure from 0.05 to 10 Torr. The cross section for collision-induced transitions out of the $2^{3}P_{0}$ level is found to be (68\ifmmode\pm\else\textpm\fi{}3) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$ at room temperature.

Physical Review•Aug 5, 1967•29 citations

Collision-Induced Transitions within Excited Levels of Neon

Joel H. Parks, Ali Javan

The interaction of an intense optical-maser field with excited atoms in a gas discharge leads to a considerable change in the population of those levels which are resonant at the maser frequency. This will cause a change in the population of other levels that are connected to the maser levels through collision-induced nonradiative as well as radiative transitions. Using the 1.15-\ensuremath{\mu} optical maser, these effects have been studied in detail for the $2s$ levels of neon where the changes are completely due to collisions. By analyzing the intensity changes in spontaneous emission originating from a gas-discharge cell placed within the maser resonator, we have observed the approach to a partial thermalization of two closely spaced levels. In this way we have been able to obtain the atomic-collision cross section for excitation transfer between the $2{s}_{2}$ and $2{s}_{3}$ levels. In pure neon this has been found to be ${\ensuremath{\sigma}}_{23}=(2.3\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$. For a helium-neon mixture the measured cross section is ${\ensuremath{\sigma}}_{23}=(1.8\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ ${\mathrm{cm}}^{2}$. The experimental method used to determine these cross sections eliminates the uncertainties caused by the effects of electron-atom collisions and radiative cascade. These techniques also yield the ratio of the Einstein coefficients for the transitions $2{s}_{2}\ensuremath{\rightarrow}2{p}_{10}$ and $2{s}_{3}\ensuremath{\rightarrow}2{p}_{10}$. The measured ratio is $\frac{{A}_{2}}{{A}_{3}}=3.0\ifmmode\pm\else\textpm\fi{}0.4$.

Physical Review•Aug 30, 1965•44 citations
The lifetime, coherence narrowing, and collision broadening of the 72S127^{2}S_{\frac{1}{2}}72S21​​ excited state of atomic thallium has been studied by the technique of zero-field level-crossing spectroscopy. The lifetime of the 72S127^{2}S_{\frac{1}{2}}72S21​​ state is determined to be 7.55 (0.08) nsec. The full coherence-narrowing effect gave a branching ratio, from F=0F=0F=0 of 72S127^{2}S_{\frac{1}{2}}72S21​​ to the ground state, of 43%. The cross section for thallium-thallium resonance-broadening collisions is \ensuremathσTl\ensuremath−Tl=5.38(0.49)\ifmmode×\else\texttimes\fi10\ensuremath−8v‾{\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{T}\mathrm{l}}=\frac{5.38(0.49)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}}{\overline{v}}\ensuremathσTl\ensuremath−Tl​=v5.38(0.49)\ifmmode×\else\texttimes\fi10\ensuremath−8​ cm2{\mathrm{cm}}^{2}cm2. The effect of 426-torr helium on the thallium lifetime, coherence narrowing, and resonance broadening was also investigated. From the low-thallium-density region the cross section for helium depolarization of the thallium 72S7^{2}S72S state is \ensuremathσTl\ensuremath−He\ensuremath≅7\ifmmode×\else\texttimes\fi10\ensuremath−13v‾{\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{H}\mathrm{e}}\ensuremath{\cong}\frac{7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}}{\overline{v}}\ensuremathσTl\ensuremath−He​\ensuremath≅v7\ifmmode×\else\texttimes\fi10\ensuremath−13​ cm2{\mathrm{cm}}^{2}cm2. There is also indication of a buildup of population in the metastable 62P326^{2}P_{\frac{3}{2}}62P23​​ thallium state. From the data, the cross section for the process Tl(62P32)\ensuremath→Tl(62P12)\mathrm{Tl}(6^{2}P_{\frac{3}{2}})\ensuremath{\rightarrow}\mathrm{Tl}(6^{2}P_{\frac{1}{2}})Tl(62P23​​)\ensuremath→Tl(62P21​​) by helium collisions is \ensuremathσ\ensuremath≃1\ifmmode×\else\texttimes\fi10\ensuremath−21\ensuremath{\sigma}\ensuremath{\simeq}1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}21}\ensuremathσ\ensuremath≃1\ifmmode×\else\texttimes\fi10\ensuremath−21 cm2{\mathrm{cm}}^{2}cm2. The Tl branching ratio in the presence of helium is 39%. It was also found that the thallium-thallium resonance-broadening cross section is \ensuremathσTl\ensuremath−Tl=4.04(0.32)\ifmmode×\else\texttimes\fi10\ensuremath−8v‾{\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{T}\mathrm{l}}=\frac{4.04(0.32)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}}{\overline{v}}\ensuremathσTl\ensuremath−Tl​=v4.04(0.32)\ifmmode×\else\texttimes\fi10\ensuremath−8​ cm2{\mathrm{cm}}^{2}cm2 in the presence of 426 torr of helium. In the presence of 113 torr of He, the resonance-broadening cross section was found to be \ensuremathσTl\ensuremath−Tl=5.22(0.13)\ifmmode×\else\texttimes\fi10\ensuremath−8v‾{\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{T}\mathrm{l}}=\frac{5.22(0.13)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}}{\overline{v}}\ensuremathσTl\ensuremath−Tl​=v5.22(0.13)\ifmmode×\else\texttimes\fi10\ensuremath−8​ cm2{\mathrm{cm}}^{2}cm2. In the case of Ar as the buffer gas, \ensuremathσTl\ensuremath−Ar=8\ifmmode×\else\texttimes\fi10\ensuremath−13v‾{\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{A}\mathrm{r}}=\frac{8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}}{\overline{v}}\ensuremathσTl\ensuremath−Ar​=v8\ifmmode×\else\texttimes\fi10\ensuremath−13​ cm2{\mathrm{cm}}^{2}cm2.
The experimental results for the self-broadening of pure Tl of the previous paper are shown to be in good agreement with the theory of resonant collisions, taking into account the effects of the hyperfine structure. Wall collisions are nearly negligible in that case. The decrease of the self-broadening observed with the addition of a foreign gas is explained in terms of three-body collisions (Tl-He collisions occurring during a Tl*-Tl collision) which broaden the optical transitions of Tl and decrease the resonance effect in the transfer of excitation between Tl atoms. The quantitative agreement obtained with the experimental results shows that these three-body collisions must be responsible for the major part of the observed reduction in self-broadening.
The lifetime and hyperfine structure of the $(6{s}^{2}6p7s) ^{3}{P}_{1}^{\ensuremath{\circ}}$ excited state in lead have been investigated by the technique of level-crossing spectroscopy. The lifetime of the state was determined to be $\ensuremath{\tau}=5.75(20)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec. The linewidth of the level-crossing signal was observed to saturate at a "coherence-narrowed" value in agreement with theoretical predictions. The magnitude of this narrowing corresponds to a 27(3)% branching ratio to the ground state. When the branching ratio and the lifetime are combined with the f(3639A˚):f(4058A˚)f(3639 \mathrm{\AA{}}):f(4058 \mathrm{\AA{}})f(3639A˚):f(4058A˚) oscillator-strength ratio measured by Khokhlov, one may infer the absolute fff values: f(2833A˚)=0.169(17)f(2833 \mathrm{\AA{}})=0.169(17)f(2833A˚)=0.169(17), f(3639A˚)=0.040(8)f(3639 \mathrm{\AA{}})=0.040(8)f(3639A˚)=0.040(8), f(4058A˚)=0.155(31)f(4058 \mathrm{\AA{}})=0.155(31)f(4058A˚)=0.155(31). The high-field level crossing in the hyperfine structure of the first $^{3}{P}_{1}^{\ensuremath{\circ}}$ state of Pb207{\mathrm{Pb}}^{207}Pb207 was found to occur at a magnetic field Hc=4661.1(4){H}_{c}=4661.1(4)Hc​=4661.1(4) G, which corresponds to a magnetic-dipole-interaction constant $A=8.811(17)\ifmmode\times\else\texttimes\fi{}{10}^{9}$ cps.
The radiative lifetime of the 21P12^{1}P_{1}21P1​ and 31P13^{1}P_{1}31P1​ state of atomic helium has been measured by the level-crossing technique. In the experiment, a beam of 21S02^{1}S_{0}21S0​ metastable atoms was first produced and then excited to the 21P12^{1}P_{1}21P1​ or 31P13^{1}P_{1}31P1​ state with resonance radiation. The lifetimes were measured by observing the zero-field level-crossing signals in the detected 584- or 537-\AA{} fluorescent radiation when these 1P1^{1}P_{1}1P1​ states decayed to the 11S01^{1}S_{0}11S0​ ground state. The results are $\ensuremath{\tau} (2^{1}P_{1})=(5.57\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ sec and $\ensuremath{\tau} (3^{1}P_{1})=(1.73\ifmmode\pm\else\textpm\fi{}0.11)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ sec. These values are in excellent agreement with theory.
The cross section for the transfer of excitation from the 23P02^{3}P_{0}23P0​ level of helium to the 23P12^{3}P_{1}23P1​ and 23P22^{3}P_{2}23P2​ levels as a result of collisions with the ground-state helium atom (11S01^{1}S_{0}11S0​) has been measured with a conventional resonance-fluorescence technique. A He4{\mathrm{He}}^{4}He4 source excited the $2^{3}S_{1}\ensuremath{-}2^{3}P_{0}$ transition in a He3{\mathrm{He}}^{3}He3 absorption cell. The scattered light was examined with a high-resolution grating spectrometer and the ratio of the $2^{3}P_{0}\ensuremath{\rightarrow}2^{3}S_{1}$ to the $2^{3}P_{1,2}\ensuremath{\rightarrow}2^{3}S_{1}$ intensities was measured as a function of cell pressure from 0.05 to 10 Torr. The cross section for collision-induced transitions out of the 23P02^{3}P_{0}23P0​ level is found to be (68\ifmmode\pm\else\textpm\fi{}3) \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}16}$ cm2{\mathrm{cm}}^{2}cm2 at room temperature.
The interaction of an intense optical-maser field with excited atoms in a gas discharge leads to a considerable change in the population of those levels which are resonant at the maser frequency. This will cause a change in the population of other levels that are connected to the maser levels through collision-induced nonradiative as well as radiative transitions. Using the 1.15-\ensuremath{\mu} optical maser, these effects have been studied in detail for the 2s2s2s levels of neon where the changes are completely due to collisions. By analyzing the intensity changes in spontaneous emission originating from a gas-discharge cell placed within the maser resonator, we have observed the approach to a partial thermalization of two closely spaced levels. In this way we have been able to obtain the atomic-collision cross section for excitation transfer between the 2s22{s}_{2}2s2​ and 2s32{s}_{3}2s3​ levels. In pure neon this has been found to be ${\ensuremath{\sigma}}_{23}=(2.3\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ cm2{\mathrm{cm}}^{2}cm2. For a helium-neon mixture the measured cross section is ${\ensuremath{\sigma}}_{23}=(1.8\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$ cm2{\mathrm{cm}}^{2}cm2. The experimental method used to determine these cross sections eliminates the uncertainties caused by the effects of electron-atom collisions and radiative cascade. These techniques also yield the ratio of the Einstein coefficients for the transitions $2{s}_{2}\ensuremath{\rightarrow}2{p}_{10}$ and $2{s}_{3}\ensuremath{\rightarrow}2{p}_{10}$. The measured ratio is $\frac{{A}_{2}}{{A}_{3}}=3.0\ifmmode\pm\else\textpm\fi{}0.4$.