On the decay of73Ga to levels in73Ge

Theγ-radiation following the β^? decay of⁷³Ga has been studied. Singlesγ andγγ coincidence spectra were recorded with Ge(Li)-detectors. 17γ-rays were assigned to transitions in⁷³Ge, where 11 excited levels are proposed. From logft values based onγ-transition intensities, spin and parity assignments for the levels were deduced. The half-life of⁷³Ga was measured to (4.86±0.03) h. From allowedβ-transitions the ground state of⁷³Ga was assigned 3/2^?.     

Lifetime measurements on excited states in100Rh

Lifetime measurements of three excited states in¹⁰⁰Rh populated by the decay of¹⁰⁰Pd have been carried out. A two parameter delayedγ-γ-coincidence experiment using an intrinsic Ge and a plastic scintillation detector resulted in the following values:T _1/2(32.72 keV,¹⁰⁰Rh)=(27.6 ±0.6) nsT _1/2(74.8keV,¹⁰⁰Rh)=(213.6±2) nsT _1/2(158.8 keV,¹⁰⁰Rh)<0.5 ns. For the levels at 32.72 keV and 158.8 keV no former values are known.     

The half-lives of the first and second excited states in 66Ga

The half-lives of the first and second excited states at 43.9 and 66.3 keV in ⁶⁶Ga were determined by measuring the time dependence of the 43.9 and 22.4 keV γ-transition intensities. The levels in ⁶⁶Ga were populated by the ⁶⁶Za(p, n)⁶⁶Ga and ⁶³Cu(α, n)⁶⁶Ga reactions. The results are T_{$\text{1}\text{2}$}(43.9 keV) = 16(4) ns and T_{$\text{1}\text{2}$}(66.3 keV) = 23(2) ns. A g-factor measurement reported in the literature is reanalysed.     

Electric field gradients at 151Eu sites in GaN

The electric field gradients at Eu sites in GaN have been investigated in conversion electron Mössbauer spectroscopy (CEMS) in which ¹⁵¹Eu probe ions were implanted into an undoped GaN layer grown on a sapphire substrate. The sample was implanted with 120 keV ¹⁵¹Eu ions to a fluence of 1 × 10¹⁵, and annealed at 1,200 K. CEMS spectra of the ¹⁵¹Eu 21.6 keV transition were collected, of the GaN sample as well as of a Si sample implanted with overlapping profiles of ¹⁵¹Eu and O. The GaN spectra were fitted with two symmetric doublets, D1 and D2, with isomer shifts and quadrupole splittings of δ?=??0.27 mm/s (relative to Eu₂O₃), ΔE _Q?= 0.85 (3) mm/s; and δ?=?? 0.22 mm/s, ΔE _Q?= 2.90 (5) mm/s, respectively. D1 is attributed to Eu at substitutional Ga lattice sites; D2 to Eu at or near substitutional sites but with extensive lattice damage. The splittings of D1 and D2 correspond to quadrupole coupling frequency of 15 (2) and 50 (4) MHz, consistent with measurements of ⁶⁹Ga, ⁷¹Ga and ¹¹¹In in GaN.     

Vibrational heating in the v2 mode of ammonia by a CO2 laser

Various levels of the v₂ mode of ammonia have been pumped by a pulsed CO₂ laser. In mixtures of NH₃ with a large excess of Ar the 1 v₂ (+), 1 v₂ (?), and 2 v₂ (?) levels could be appreciably populated. The level populations were monitored by absorption spectroscopy in the ultraviolet using appropriate vibronic transitions of the ùA^″₂←X?¹A₁ absorption band . The energy balance was examined by comparing the number of molecules removed from the ground state with the number densities in the vibrationally excited levels and with the number of photons absorbed during the laser pulse. While the ground-state depletion corresponds well to the excited-state populations only a fraction of the photons deposited can be accounted for in the excited molecules. This is consistent with the assumption of very fast V-T relaxation.     

A tentative multiphoton ionization of CS2 molecule: Spectroscopy of Ã2πu state of CS 2 + ion

The spectroscopic study of excited molecular cationCS ₂ ⁺ (òπ_u ) by a different method is presented. In this technique the decay of excited states is monitored by measuring the photons emitted. The peaks in the photon spectrum would correspond to the energy levels of the ion. The vibrational-vibrational, vibrational-electronic interactions have been observed. Symmetry forbidden excitation of one quantum of bending vibration is observed which gives unperturbed value for the bending vibration. The Renner-Teller splitting for the δ_g and Σ _g ^- components of the bending mode (v ₂ ^′ = 1) in the upper excited òπ_u state has been observed. A tentative vibrational analysis of the Ã→ X system has been made.     

Stepwise ionization in a non-equilibrium,steady-state hydrogen plasma

The paper considers a non-equilibrium, steady-state hydrogen plasma with 10¹⁰ ? N_e, cm^-3 ? 10¹⁷ and 8000 ? T_e, °K ? 64,000. The following two cases are analyzed: (1) the plasma is optically thin for all atomic lines and (2) the plasma is optically thick towards the Lyman lines and optically thin for all other lines. Analytical expressions have been obtained for populations and ionization frequencies of excited levels. Populations of the excited levels obtained from the analytical formulas are in good agreement with numerical calculations.     

High resolution Raman spectroscopy of the fundamental vibrational band of 16O2

The vibrational Raman spectrum of ¹⁶O₂ has been recorded with high resolution (0.05 cm^?1 for the Q branch). The expansion of the Hamiltonian as a sum of irreducible tensors of the O(3) group allowed us to obtain easily the expressions for the energy levels, taking into account the off-diagonal matrix elements. From the analysis of the spectrum the excited state constants have been calculated; in particular the rotational constants obtained are: B₁ = 1.421884 ± 0.000013 cm^?1 and D₁ = (?4.864 ± 0.014)10^?6 cm^?1.     

Half lives of the 482.2 keV and 615.3 keV levels in181Ta

The half lives of the excited levels at 482.2 keV and 615.3 keV in¹⁸¹Ta have been measured by the delayed coincidence technique. In the nanosecond time range (482.2 keV level) the most serious sources of errors are jitter, walk and drift phenomena. To minimize those the time pick-off has been defined carefully by means of modern fast timing detectors and electronics. In the microsecond time range (615.3 keV level) the ratio of true delayed coincidences to chance coincidences influences considerably the final accuracy of the half-life measurements. It has been reduced as much as possible. From a series of independent measurements half lives ofT _1/2=(10.67±0.05) ns andT _1/2=(17.64±0.14) μs have been deduced for the 482.2 keV and 615.3 keV levels, respectively. The results have been compared with other values published before.     

Magnetic moment measurement of the 15/2+, 3578 keV level in67Ga

The magnetic moment μ=−(1.69±0.47) μ_N of the 15/2⁺, 3578 KeV level in⁶⁷Ga was determined from measurements of the integral perturbed angular distributions in implanted sources. The excited levels were populated by the reaction⁵⁶Fe(¹⁶O, αp)⁶⁷Ga.     

Tunable laser study of the ν10 + ν11 band of cyclopropane

Diode laser measurements of the ν₁₀ + ν₁₁ (l_tot = ±2) perpendicular band of cyclopropane have led to the assignments of roughly 600 lines in the 1880–1920-cm^?1 region. Most of the spectra were recorded and stored in digital form using a rapid-scan mode of operating the laser. These spectra were calibrated, with the aid of a computer, by reference to the R lines of the ν₁ + ν₂ band of N₂O. The ground state constants we obtained are (in cm^?1) B = 0.670240 ± 2.4 × 10^?5, D_J = (1.090 ± 0.054) × 10^?6, D_JK = (?1.29 ± 0.19) × 10^?6, D_K = (0.2 ± 1.1) × 10^?6. The excited state levels are perturbed at large J values, presumably by Coriolis couplings between the active E′(l_tot = ±2) and the inactive A′(l_tot = 0) states. Effective values for the excited state constants were obtained by considering only the J < 15 levels. The A₁-A₂ splittings in the K′ = 1 excited states were observed to vary as q_effJ(J + 1), with q_eff = (2.17 ± 0.17) × 10^?4 cm^?1.     

Life-times of the 4 1 + -states in134Te and136Xe

The half-lives of the first excited 4⁺-levels in theN=82 isotones ₅₂ ¹³⁴ Te and ₅₄ ¹³⁶ Xe have been determined tot _1/2=(1.50±0.13) ns andt _1/2=(1.32±0.10) ns, respectively, through the measurement of delayedγ,γ-coincidences. The value for¹³⁴Te is in agreement with the assumption that the low lying levels of this nucleus are based mainly on theg ₇ ^{2 /2} proton configuration. In¹³⁶Xe the half-life is unexpectedly small which indicates a more strongly admixed structure of the levels involved in this case.     

Lifetime measurement in the α system (C3Δ3-X3Δ3) of TiO

The radiative lifetimes of two rotational levels of the v′ = 2 level of the C³Δ₃ state of TiO have been measured using laser-induced fluorescence and delayed coincidence counting. Individual rotational levels are excited and observed. The measured lifetimes are τ_{J = 17} = 28.21 + 0.15 nsec and τ_{J = 87} = 29.74 ± 0.86 nsec. Argon-TiO collision cross sections have been determined for the two rotational levels and are found to differ by 30%.     

The quadrupole moment of 26Mg as a test of shell-model interactions

The static quadrupole moment Q_21⁺, and the B(E2; 0₁⁺ → 2⁺₁) value of the first excited state of²⁶Mg have been measured using the reorientation effect in Coulomb excitation of ²⁶Mg projectiles. It is found that Q_21⁺ = ?13.6±3.0 (?9.5±3.0) e ·fm² and B(E2; 0⁺₁ → 2⁺₁) = 322±16 (328±16) e² ·fm⁴ for constructive (destructive) interference from higher states. The result for Q₂ clearly differentiates among several alternative effective interactions which have been used in shell-model calculations.     

High-spin states in68Ga

The⁶⁸Ga nucleus has been studied via the reactions⁶⁵Cu(α, nγ)⁶⁸Ga atE _α=12–21 MeV and⁶⁶Zn(α, p nγ)⁶⁸Ga atE _α=25–40 MeV. The level scheme has been established by means of relative yield functions, electronic timing measurements, prompt and delayedγ-γ coincidences, angular distributions and directional orientation coÏncidences. Spins up to 11⁺ were assigned to levels up to 4 MeV excitation and the higher ones were interpreted by coupling a⁶⁷Ga core with a (v 1 g_9/2) neutron.     

Properties of excited levels in102Rh by the102Ru(p,nγ) reaction

The level scheme of¹⁰²Rh has been investigated by the¹⁰²Ru(p, nγ) reaction in the proton energy range 3.1 MeV≦E _p≦6 MeV. Excitation functions,γ-γ coincidences and pulsed beam measurements have been performed and a level scheme including 33 excited states up toE _x≈650 keV has been constructed. Theγ-branchings of several levels have also been measured. The lifetimes of 5 excited states have been determined with the centroid-shift method:τ _m(105.2 keV)=(1.3±0.3) ns,τ _m(123.7 keV)=(0.6±0.3) ns,τ _m(178.6 keV)=(1.5±0.3) ns,τ _m(208.7 keV)=(0.5±0.3) ns,τ _m(359.6 keV)=(0.8±0.4) ns. Upper limits have been placed for the lifetimes of 20 other levels.     

Fine-structure mixing of excited states of cesium atoms upon an impact on the surface of a sapphire single crystal

The spectrum of resonantly excited luminescence of Cs atoms in a microcell with sapphire windows has been studied. Spectral wings of atomic luminescence near the windows have been revealed near (±50 cm^?1) the D2 line of the excited 6S _1/2–6P _3/2 transition. At the same time, the radiation of the D1 line has been found. The features of the spectrum of the far wings, namely, the exponential shape and the relatively small difference between the static and the antistatic wings, as well as the radiation of the D1 line, have been explained by the mixing of fine-structure states due to interactions of Cs atoms with the sapphire windows. From the relative intensity of the lines, it has been determined that the probability of luminescence quenching at the window surfaces differs from unity by no less than 1/700.     

Transitions between Zeeman substates of excited He I levels induced by electric radiofrequency fields

Making use of the large tensor polarizabilities of excited He I levels, transitions between Zeeman substates of 1snd ¹ D ₂ levels have been induced by electric radiofrequency fields after ion-impact excitation of He atoms. Resonance signals have been observed near the Larmor frequencyω=ω _L as well as nearω=2ω _L . These signals are interpreted as 2-quantum electric-dipole (2E1) transitions and 1E1 transitions, respectively, between the Zeeman sublevels withM=0 andM=±2. The interaction of this 3-state system {¦M〉;M=?2, 0, +2} with the applied external fields (magnetic fieldH _z and static and alternating electric field?=? ₀+? ₁ cosω t) is discussed. The shape of the resonance signals has been evaluated in the rotating field approximation. In contradiction to the theory, the observed signals show a peculiar narrow structure at the center of the signal which is not yet completely understood. The experimental techniques developed are expected to be useful for investigations of Zeeman-, Stark-, fine and hyperfine splittings of excited He I levels.     

Nuclear resonance fluorescence in94Mo,95Mo and96Mo

Using gaseous sources of Tc₂O₇ containing the radioactive isotopes⁹⁴Tc,⁹⁵Tc and⁹⁶Tc, levels at 871.0keV (⁹⁴Mo), 765.8, 820.6, 947.8, 1074.0keV (⁹⁵Mo) and 778.3keV (⁹⁶Mo) have been excited. From the effective cross sections for nuclear resonance scattering and from the lifetimes of the 947.8, 1074.0 and 778.3keV levels known from Coulomb excitation experiments the profiles of theγ-lines have been determined. A broadening of theγ-lines due to Coulomb explosion of the molecules has been observed. Making use of the line profiles, lifetimes ofΤ=(6.4±1.0) ps andΤ=(0.90 ± 0.20) ps have been determined for the 765.8 and 820.6keV levels, respectively. The angular distribution of the resonantly scattered radiation yields an amplitude ratioδ for the mixed M1 E2 765.8keV transition ofδ=0.14 _?0.009 ^+0.08 . TheB(E2) from a Coulomb excitation experiment and the lifetimeΤ from the present experiment yield ¦δ¦=0.07±0.01 for the 820.6keV transition.     

Particle-hole multiplets in 40Ca observed in the 41Ca(τ, α) reaction

Energy levels in ⁴⁰Ca up to 10.2 MeV have been studied in the neutron pickup reaction ⁴¹Ca(τ, α)⁴⁰Ca with 20 MeV bombarding energy. Thirty excited states have been identified and angular distributions have been measured in the interval from 5° to 40° by means of a split-pole magnetic spectrometer. The angular distributions together with DW calculations have been used to extract l_n values and spectroscopic factors. The l_n = 2 strength distribution for the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$ particle-hole levels is compared to the l_p = 3 strength distribution from pr stripping data.