Hyperfine structure of the 72P states of thallium by doppler-free two-photon absorption

Using Doppler-free two-photon absorption, we have measured the hyperfine splittings (hfs) and isotope shifts of the 7²P states of natural thallium. We obtain $\text{A(7}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{= 310(8) Mhz}$, and $\text{A(7}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 2131(60) Mhz}$. Surprisingly, the 7²P_{$\text{3}\text{2}$} state hfs is larger than that of the 6²P_{$\text{3}\text{2}$} state.     

New measurements of the n2P12,32 energy levels of Cs(I)

The energies of the $\text{n}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(7 ≤ n ≤ 13)}$ and $\text{n}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{(7 ≤ n ≤ 27)}$ levels of CsI have been redetermined photographically from high resolution absorption measurements of the principal series lines $\text{6}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? n}{}^2\text{P}{}_{\mathrm{<mtext>J</mtext>}}$X. The new data disagree significantly [ ≈0.13 cm^-1] with the values given in the NBS-Tables of Moore¹ which are taken from a paper by Kratz.² By means of an extended Ritz-formula, the ionization energy of CsI was found to be 31406.46±0.03 cm^-1, which is, within the limit of uncertainty, in agreement with the data of Kleiman,³ Eriksson et al.,⁴ Bockasten,⁵ and Eriksson and Wenåker.⁶     

Radiative lifetimes in MoI using a novel atomic beam source

Radiative lifetimes of the 4d⁵ (a⁶S)5pz ⁷P^o levels and the 4d⁵ (a⁶S)5pz⁵P^o levels in MoI are reported as follows: $\text{τ(}\text{z}{}^7\text{P}{}_4{}^{\mathrm{<mtext>O</mtext>}}\text{) = 15.9}\text{ns}$, $\text{τ(}\text{z}{}^7\text{P}{}_3{}^{\mathrm{<mtext>O</mtext>}}\text{) = 17.0}\text{ns}$, $\text{τ(}\text{z}{}^7\text{P}{}_2{}^{\mathrm{<mtext>O</mtext>}}\text{) = 17.1}\text{ns}$, $\text{τ(}\text{z}{}^5\text{P}{}_3{}^{\mathrm{<mtext>O</mtext>}}\text{) = 22.3}\text{ns}$, $\text{τ(}\text{z}{}^5\text{P}{}_2{}^{\mathrm{<mtext>O</mtext>}}\text{) = 22.1}\text{ns}$, and $\text{τ(}\text{z}{}^5\text{P}{}_1{}^{\mathrm{<mtext>O</mtext>}}\text{) = 21.7}\text{ns}$ (±5%). The lifetimes are measured using time resolved laser induced fluorescence and a novel atomic beam source. This novel hollow cathode effusive beam source produces an intense beam of ground state Mo atoms and metastable Mo atoms. Our measurements on the z ⁷P^O levels are in agreement with earlier lifetime measurements. Our measurements on the z ⁵P^O levels are the first direct radiative lifetime measurements of these levels; the z ⁵P^O measurements are of particular interest because the a⁵S → z⁵P^O multiplet is used to determine the solar abundance of Mo.     

Hyperfine structure of the 53P1 state of 115Cdm

The magnetic fields at which Zeeman sublevels cross in the excited 5³P₁ state of the 43-day isomer ¹¹⁵Cd^m have been determined for three pairs of levels. The crossing fields are used to determine the magnetic dipole hyperfine structure constant $\text{A(}{}^3\text{P}{}_1\text{) = ?656.491 (4)}\text{MHz}$ and the quadrupole constant $\text{B(}{}^3\text{P}{}_1\text{) = 129.39 (6)}\text{MHz}$.     

Observation of the 6 2P12−7 2P12 M1 transition in atomic thallium vapor

The $\text{6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{?7}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ (292.7 nm) M1 transition in Tl is observed and its matrix element $\text{m = 〈7}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{|μ}{}_{\mathrm{Z}}\text{| 6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{〉}$ is measured. Tl vapor is illuminated by a pulsed linearly polarized laser beam (λ = 292.7 nm). Interference between m and the Stark-induced $\text{6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{?7}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ E1 amplitude in finite electric field E results in circular polarization of 535 nm fluorescence proportional to m/E, which is detected. The result is m = ?(2.11 ± 0.30) × 10^?5 | eh/2m_ec| in agreement with theory. The ultimate goal of this research is to detect parity violation in the neutral weak interaction by observation of a helicity dependence in the $\text{6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{?7}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ absorption when the laser light is circularly polarized.     

Lifetime measurements of the 6p2P and 6d2D levels in Hg(II)

The radiative lifetimes of the 6p²P levels in Hg(II) have been measured to be $\text{τ(6p}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)= 3.92±0.12)}$ ns and $\text{τ(6p}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)=(2.3±0.3)}$ ns by the beam-gas-Hanle and the beam-foil techniques, respectively. The result for the $\text{6p}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ level differs from recent theoretical calculations, whereas there is good agreement for the $\text{6p}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ level.     

Stark mixing spectroscopy in cesium

We present a new technique for selectively populating excited states which are inaccessible by dipole excitation from the ground state. The method uses a static electric field to introduce a component of a dipole-allowed state into the state of interest. We have applied the method to cesium to measure lifetimes and a Stark mixing coefficient. The results are $\text{τ(6}{}^2\text{D}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)=64(2) ns}$, $\text{τ(7}{}^2\text{D}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)=92.5(15) ns}$, and <6²D_{$\text{5}\text{2}$}|;ez |7²P_{$\text{3}\text{2}$}>/(E_7P?E_6D)=0.7(3)×10^?3 where is in kV/cm. 141     

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: $\text{6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? 7}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? 8}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ in the presence of a static magnetic field; and $\text{6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? 7}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{, 6}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? 8}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$in the absence of any external field.     

Dye laser site selection spectroscopy on U6+ luminescent molecular centers in LiF-U3O8 crystals

The polarized excitation and emission spectra of the U⁶⁺ molecular centers giving the most intense emission lines at 18 940 cm^?1 and 19 285 cm^?1 are presented and analyzed in detáil. From the polarization experiments, it is shown that the symmetry of the centers is C_4v and that the symmetries of the observed electronic states are Γ₂, Γ₁ and Γ₅. Finally, an electronic model is proposed which associates the emission and excitation lines of the U⁶⁺ centers in the visible region to transitions between the fundamental state $\text{Γ}{}_1\text{(6p}{}^6\text{,}{}^1\text{S)}$ and the states of the excited configuration $\text{6p}{}^5\text{(}{}^2\text{P}\text{3}\text{2}\text{) 7s}$.     

Band contour analysis of compounds with pure isotopes: The E fundamentals of HC35Cl3

The vibration-rotation transitions for v = 1 ← 0 of NO (${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$) have been studied by using the technique of laser magnetic resonance spectroscopy. Five magnetic resonance lines are observed with three CO laser lines in the range from 1859 to 1886 cm^?1. From these, three zero-field transition frequencies, v = 1 ← 0; $\text{R(}\text{3}\text{2}\text{)}$, $\text{P(}\text{7}\text{2}\text{)}$, and $\text{P(}\text{9}\text{2}\text{)}$ are obtained with an accuracy of ±0.0007 cm^?1. The molecular constants which have been determined by borrowing centrifugal constants from a previous infrared work are $\text{B}{}_{02}{}^1\text{= 1.72004 ± 0.00006}\text{cm}{}^{\mathrm{?1}}$, $\text{B}{}_{12}{}^1\text{= 1.70212 ± 0.00010}\text{cm}{}^{\mathrm{?1}}$, and $\text{G(v = 1) ? G(v = 0) (}\text{for}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{) = 1875.8470 ± 0.0007}\text{cm}{}^{\mathrm{?1}}$.     

Electromagnetic annihilation of e+e− into quarkonium states with even charge conjugation

We calculate the production of narrow resonances with even charge conjugation ${}^3\text{P}{}_{\mathrm{J}}\text{=1,2}$ in e⁺e^? annihilation in the quarkonium and vectordominance models. We give unitarity bounds for $\text{Γ(}{}^3\text{P}{}_{\mathrm{J}}\text{→ e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{)}$ in terms of $\text{Γ(}{}^3\text{P}{}_{\mathrm{J}}\text{→ γγ)}$ and $\text{Γ(}{}^3\text{P}{}_{\mathrm{J}}\text{→ e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{)}$. The electromagnetic production dominates through the neutral current at low energies independent of details of the model. For masses above 10 GeV the situation is reversed.     

Lifetimes and g-factors of the 6− and 7− isomers in 66Ga and 68Ga

The 6^? and 7^? isomeric states in ⁶⁶Ga and ⁶⁸Ga at 1440.9 and 1229.6 keV, respectively, have been populated with the (¹³C, 2np) and (¹⁵N, n2p) reactions on natural Fe. The half-lives of these states have been measured to be $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(6}{}^{\mathrm{?}}\text{,}{}^{66}\text{Ga}\text{) = 57.3 ± 1.2}\text{ns}$ and $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(7}{}^{\mathrm{?}}\text{,}{}^{68}\text{Ga}\text{) = 64 ± 2}\text{ns}$. Using previous data on the hyperfine field of Ga in Fe, the g-factors of these states have been determined by means of the TDPAD method. The results are $\text{g(6}{}^{\mathrm{?}}\text{,}{}^{66}\text{Ga}\text{) = 0.129 ± 0.003}$ and $\text{g(7}{}^{\mathrm{?}}\text{,}{}^{68}\text{Ga}\text{) = 0.105 ± 0.003}$. These values are in very good agreement with the independent particle model if one assumes the and configurations and uses the empirical proton and neutron g-factors from odd-A neighboring nuclei instead of the Schmidt values. The large disagreements with experiment when Schmidt values are used show that core polarization effects are important in these nuclei.     

Observed and calculated interactions between valence states of the NO molecule

No perturbation between two valence states of NO has ever been identified, although many valence-Rydberg and several Rydberg-Rydberg perturbations have been extensively studied. The first valence-valence crossing to be experimentally documented for NO is reported here and occurs between the ¹⁵N¹⁸O B²Π (v = 18) and B′²Δ (v = 1) levels. No level shifts larger than the detection limit of 0.1 cm^?1 are observed at the crossings near $\text{J = 6.5 [B}{}^2\text{Π}\text{(F}{}_1\text{) ～ B′}{}^2\text{Δ}\text{(F}{}_2\text{)]}$ and $\text{J = 12.5 [B}{}^2\text{Π}\text{(F}{}_1\text{) ～ B′}{}^2\text{Δ}\text{(F}{}_1\text{)]}$; two crossings involving higher rotational levels could not be examined. Semi-empirical calculations of spin-orbit and Coriolis perturbation matrix elements indicate that although the electronic part of the $\text{B}{}^2\text{Π}\text{～ B′}{}^2\text{Δ}$ interaction is large, a small vibrational factor renders the ¹⁵N¹⁸O B (v = 18) ? B′ (v = 1) perturbation unobservable. Semi-empirical estimates are given for all perturbation matrix elements of the operators $\text{Σ}{}_{\mathrm{i}}\text{a}\text{?}{}_{\mathrm{i}}\text{l}{}_{\mathrm{i}}\text{·s}{}_{\mathrm{i}}$ and $\text{B(L}{}_{\mathrm{\pm }}\text{S}{}_{\mathrm{?}}\text{? J}{}_{\mathrm{\pm }}\text{L}{}_{\mathrm{?}}\text{)}$ which connect states belonging to the configurations $\text{(σ2p)}{}^2\text{(π2p)}{}^4\text{(π}{}^1\text{2p)}$, $\text{(σ2p)(π2p)}{}^4\text{(π}{}^1\text{2p)}{}^2$, and $\text{(σ2p)}{}^2\text{(π2p)}{}^3\text{(π}{}^1\text{2p)}{}^2$.     

Forces d'oscillateur du potassium

We describe the results of measurements on emission and absorption of potassium I lines obtained in two series of experiments. The first concerns a low-pressure flame fed by a methane and oxygen mixture, seeded with potassium carbonate, and the other an atmospheric- pressure helium plasma seeded with potassium.A collation of the experimental results of the latter series and Drawin's theory about the conditions of validity for local thermodynamic equilibrium show that the transition-probability values measured by Heiërman are incorrect. Warner's theoretical values are more satisfactory. This study allows us to propose new oscillator strengths for the KI lines corresponding to the following transitions: $\text{4}{}^2\text{P}{}^0{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? 7}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, $\text{4}{}^2\text{P}{}^0{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{? 10}{}^2\text{S}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{? 11}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of the sharp series and $\text{4}{}^2\text{P}{}^0{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{? 6}{}^2\text{D}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext><mtext>5</mtext><mtext>2</mtext>}}$ of the diffuse series.     

Lifetime measurements of 7P levels of Cs(I) by means of laser excitation

Measurements of the lifetimes of the $\text{7}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{7}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ levels of Cs are described. The populations of these excited levels were produced by using a tunable dye laser. The fluorescence signals from a gated photomultiplier were recorded by analog sampling. The results of the measurements are 133±2 and 155±4 ns for the 7${}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ levels, respectively.     

42P fine-structure mixing in potassium by collisions with N2, H2, CO,and CH4

Cross sections for $\text{4}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{?4}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ fine-structure mixing in potassium, induced in collisions with N₂, H₂, CO, and CH₄, were determined by methods of atomic fluorescence spectroscopy. The experiments were carried out at a temperature of 342 K, a K density of 6 × 10⁹ cm^?3 and mtorr buffer gas pressures, and yielded the following cross sections $\text{Q}{}_1\text{(4}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→4}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$) and $\text{Q}{}_2\text{(4}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→4}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ (in units of 10^?6 cm²): for N₂, 79 and 54; for H₂, 57 and 39; for CO, 98 and 64; for CH₄, 86 and 58. The values for N₂ and H₂ supersede those reported previously by McGillis and Krause (1968).     

Determination of the isotope shift of 190Hg by on-line laser spectroscopy

By use of a pulsed tunable dye laser the isotope shift of $\text{(T}\text{1}\text{2}\text{= 20 min)}$¹⁹⁰Hg in the $\text{6s}{}^2{}^1\text{S}{}_0\text{?6s6p}{}^3\text{P}{}_1$, λ = 2537 Å line has been measured at the on-line mass separator ISOLDE/CERN. The preliminary result relative to ²⁰⁴Hg is $\text{IS}{}^{\mathrm{<mtext>204</mtext><mtext>190</mtext>}}\text{= 31.8(3) GHz}$.     

A study of the excited electronic states of 9-fluorenone

Some spectroscopic properties of the low-energy electronic states of 9-fluorenone have been examined. The spectra in paraffin matrices at 4.2°K show detailed vibrational spectra. Two fluorescence spectra are observed; a diffuse emission arises from 9-fluorenone crystals in the paraffin matrix, and a sharp emission is characteristic of the molecule. The sharp fluorescence is analyzed in terms of known a₁ vibrational fundamentals. The sharp absorption is a near mirror-image to the fluorescence, so Herzberg-Teller vibrations are not prominent. The polarization in the crystal spectrum allows this low-energy transition near 23 000 cm^?1 to be assigned ${}^1\text{B}{}_2\text{←}{}^1\text{A}{}_1$. Because there is no vibronic perturbation in fluorescence, and certainly no out-of-plane modes, a $\text{π}{}^1\text{← n}$ transition seen at about 26 000 cm^?1 is tentatively assigned ${}^1\text{B}{}_1\text{←}{}^1\text{A}{}_1$. Another sharp absorption system is seen at 31 000 cm^?1 in the paraffin matrices at 4.2°K (linewidth 6 cm^?1) but no fluorescence was detected. The polarized crystal spectrum indicated the assignment of this system and another very strong system at 40 000 cm^?1 to be ${}^1\text{B}{}_2\text{←}{}^1\text{A}{}_1$, while other systems at about 34 000 cm^?1 and 44 000 cm^?1 are ${}^1\text{A}{}_1\text{←}{}^1\text{A}{}_1$.The phosphorescence spectrum of pyrene-d₁₀ held in a single crystal of 9-fluorenone at 4.2°K has been recorded. No delayed fluorescence from the host crystal is observed at 4.2°K but is intense at 77°K. The energy difference between host and guest triplet levels is estimated to be about 900 cm^?1 allowing the lowest triplet state of 9-fluorenone to be placed at 17 800 cm^?1.