Atomic Thallium Research Articles

Observation of Stimulated Level Shifting in Inverted Atomic Thallium Populations

Level shifting has been observed in a two-level, two-isotope atomic system which is undergoing stimulated emission. The optical fields which produce the level shifts are generated by the same stimulated process.

Preliminary Observation of Parity Nonconservation in Atomic Thallium

Parity nonconservation is observed in the $6^{2}P_{\frac{1}{2}}\ensuremath{-}7^{2}P_{\frac{1}{2}}$ transition in thallium. Absorption of circularly polarized 293-nm photons by $6^{2}P_{\frac{1}{2}}$ atoms in an $E$ field results in polarization of the $7^{2}P_{\frac{1}{2}}$ state through interference of Stark $E1$ amplitudes with $M1$ and parity-nonconserving $E1$ amplitudes $\mathfrak{M}$ and ${\mathcal{E}}_{p}$. Detection of this polarization yields the circular dichroism $\ensuremath{\delta}=+(5.2\ifmmode\pm\else\textpm\fi{}2.4)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$, which agrees in sign and magnitude with theoretical estimates based on the Weinberg-Salam model.

Efficient thallium photodissociation laser

We report on an atomic thallium laser at 535.0 and 377.6 nm which is pumped by the photodissociation of TlI with the 193-nm output of an ArF laser. High-resolution Fabry-Perot scans of the 535.0-nm line have shown a structure in the laser spectrum which depends on the Tl inversion density. The energy efficiency for conversion of the pump into thallium laser emission has been measured to be 14±3%.

Optical second-harmonic generation in atomic thallium vapor

We observe coherent optical second-harmonic generation in atomic thallium vapor when the fundamental is tuned to half the resonance frequency of the following transitions: 6 2P 1 2 − 7 2P 3 2 and 6 2P 1 2 − 8 2P 3 2 in the presence of a static magnetic field; and 6 2P 1 2 − 7 2P 1 2 , 6 2P 1 2 − 8 2P 1 2 in the absence of any external field.

Atomic fluorescence spectrometry of thallium with a frequency-doubled dye laser and vitreous carbon atomizer

A vitreous carbon atomizer is described for use in laser-excited atomic fluorescence spectrometry and is applied to the determination of thallium in aqueous solution. When a frequency-doubled N 2 laser-pumped dye laser is used to excite the atomic thallium at 276.8 nm and the combined direct-line fluorescence and stepwise-line fluorescence are detected at 352.9 and 351.9 nm, respectively, the limit of detection is 2.5 × 10 -14 g in a 0.5-pg ml -1 sample solution. The calibration curve for thallium has a linear range extending over six orders of magnitude.

Tensor polarizability of the ground-state hyperfine structure of thallium

The atomic-beam magnetic-resonance technique has been used to measure the hyperfine-structure tensor polarizability (quadratic Stark effect) in the ${6}^{2}{P}_{\frac{1}{2}}$ ground state of atomic thallium. Electric fields of up to 460 kV/cm were used to lift the degeneracy between the ${m}_{F}=0$ and the ${m}_{F}=\ifmmode\pm\else\textpm\fi{}1$ substates in the absence of an external magnetic field, and focusing transitions between these Stark-separated states were observed. Measurements were also made between Zeeman-separated substates. The results are ${\ensuremath{\alpha}}_{T}=\ensuremath{-}(3.74\ifmmode\pm\else\textpm\fi{}0.09)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ Hz/${(\mathrm{V}/\mathrm{c}\mathrm{m})}^{2}$, or $k=\ensuremath{-}(5.62\ifmmode\pm\else\textpm\fi{}0.14)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ Hz/${(\mathrm{V}/\mathrm{c}\mathrm{m})}^{2}$, where $\ensuremath{\delta}\ensuremath{\nu}=k{E}^{2}$ is the Stark shift of the $({m}_{F}=0)\ensuremath{\leftrightarrow}({m}_{F}=\ensuremath{-}1)$ "flop-in" transition.

New method for preparation of cyclopentadienylthallium and cyclopentadienylindium by reaction of zero-valent Tl0 and In0 with cyclopentadiene

1. The IR spectra of samples, obtained by the cocondensation of atomic thallium and indium with cyclopentadiene at 77°K, were measured. The atomic thallium and indium react directly with the cyclopentadiene in the obtained matrix to respectively give cyclopentadienylthallium and cyclopentadienylindium. 2. The IR spectrum of cyclopentadienylindium was obtained for the first time.

Spontaneous Raman scattering in atomic thallium vapor

Using a cw argon-ion laser, we have measured the spontaneous Raman scattering cross section, σ R, and linewidth in atomic thallium vapor. For 4880-Å excitation, σ R = 1.6 × 10 −27 cm 2. We observe no pressure broadening of the Raman line at vapor pressures to 100 torr.

Level-Crossing Spectroscopy in7S2Thallium. I. Studies of Coherence-Narrowing, Collision-Broadening, and Buffer-Gas Effects

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, ${\ensuremath{\sigma}}_{\mathrm{T}\mathrm{l}\ensuremath{-}\mathrm{A}\mathrm{r}}=\frac{8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}}{\overline{v}}$ ${\mathrm{cm}}^{2}$.

Electronic stimulated Raman scattering in atomc thallium vapor

Non-resonant stimulated electronic Raman scattering has been observed in atomic thallium vapor. The Stokes shift is 7793 cm -1. Approximately 12% of the laser photons were converted. The Stokes polarization was measured and laser-beam self-focusing was observed.

Far-Infrared Absorption in a Lead-Thallium Superconducting Alloy

Preliminary measurements have been made of the absorption of far-infrared radiation in the surface of a bulk superconducting alloy composed of lead with 10.0 atomic percent thallium at 1.4°K. The results indicate that the gap edge is quite distinct, in contrast to previous results of Richards and Tinkham on other alloys. The sharpness of the gap edge is thought to be characteristic of alloys which are homogeneous and have no trapped magnetic flux. Alloying narrows the observed gap width by about the same ratio as the critical temperature, and by an amount which is much smaller than that predicted by Suhl and Matthias from a simplified model. The subsidiary absorption maximum below the gap edge, which has been seen previously in pure lead, is also present in the alloy. This lends support to other evidence that itis not due to crystalline anisotropy.