Atomic beam magnetic resonance investigations in the3 F 2 Ground State of177Hf,179Hf and180Hf

The 5d ²6s ^{2 3} F ₂ ground state of¹⁷⁷Hf,¹⁷⁹Hf and¹⁸⁰Hf has been studied using the atomic beam magnetic resonance method. The atomic beam was produced by an universal evaporation technique described in a previous paper. The results are¹⁸⁰Hfg _j (³ F ₂)=0.695812 (10)¹⁷⁷Hf Δv(³ F ₂;F=11/2?F=9/2)=991.7917 (10) MHz Δv(³ F ₂;F=9/2?F=7/2)=477.0081 (10) MHz Δv(³ F ₂;F=7/2?F=5/2)=162.8890 (10) MHz¹⁷⁹HfΔv(³ F ₂;F=13/2?F=11/2)=82.1320 (10) MHz Δv(³ F ₂;F=11/2?F=9/2)=392.8498 (10) MHz. The magnetic dipole and electric quadrupole moments of the¹⁷⁷Hf and¹⁷⁹Hf nuclear ground states as calculated from these hyperfine structure measurements are the following: μ(177)=0.75(8)μ _k , Q(177)=4.34 (65) barns μ(179)=?0.61 (6)μ _k , Q(179)=4.90 (75) barns.     

Polarization labelling spectroscopy of the A 1Σ+u band of Na2

A result of the polarization labelling spectroscopy of the A ¹Σ⁺_u band of sodium dimer for the high vibrational quantum number υ'>20 is reported. The frequency difference δv=v_obs-v_cal is found to decrease from 2 to -3 cm^-1 as the rotational levels (υ'=27?30), where v_cal is the calculated transition frequency using the Dunham coefficients of Demtröder and Stock for the X ¹Σ⁺_g band and of Kusch and Hessel for the A ¹Σ⁺_u band.     

Bestimmung des elektrischen Kernquadrupolmomentes des ungeraden stabilen Strontium-87-Kerns

In order to determine the electric quadrupole moment of Sr⁸⁷ (I= 9/2) the hyperfine structure-splitting of the 5s5p ³ P ₁-state of the SrI-spectra was investigated by optical double resonance. By detection of high frequency transitions (ΔF=±1,Δm _F=0,±1) in an external magnetic fieldH ₀≈0 one obtains the hyperfine structure separations asv _F=11/2?F=9/2=1463·149 (6) Mc/sec andv _F=9/2?F=7/2=1130·264 (6) Mc/sec. From these frequencies one calculates the magnetic hyperfine structure-splitting constantA=?260·084 (2) Mc/sec and the electric quadrupole interaction constantB=?35·658 (6) Mc/sec. B leads to an electric quadrupole moment ofQ(Sr⁸⁷)=+0·36 (3)·10^?24 cm².     

The 2ν1, 2ν2 and 2ν3 overtones of FClO3

The infrared spectra of the 2ν₁, 2ν₂ and 2ν₃ overtones of perchloryl fluoride, FClO₃, have been recorded at high resolution using monoisotopic pure samples. Four symmetric top species have been investigated: F³⁵Cl¹⁶O₃, F³⁷Cl¹⁶O₃, F³⁵Cl¹⁸O₃ and F³⁷Cl¹⁸O₃. The v_i = 2, i = 1, 2, 3 vibrationally excited states are totally symmetric, so these overtones correspond to parallel bands of medium/weak intensity, centered from 2010 to 2120 cm⁻¹ (2ν₁), from 1390 to 1430 cm⁻¹ (2ν₂) and from 1070 to 1100 cm⁻¹ (2ν₃). Most of the bands are unperturbed and their analysis was straightforward. The band origins, the rotational and centrifugal molecular constants in the v₁ = 2, v₂ = 2 and v₃ = 2 states have been determined, with standard deviations of the fits from 0.00024 to 0.00067 cm⁻¹. The 2ν₁ overtones of F³⁵Cl¹⁶O₃ and F³⁷Cl¹⁶O₃ are perturbed by an A₁/E Coriolis resonance between the v₁ = 2 state and one E component of the v₄ = 1, v₆ = 2 manifold. The 2ν₂ of F³⁷Cl¹⁸O₃ is perturbed by the same kind of interaction involving the v₁ = v₆ = 1 (E) state, at about 1396 cm⁻¹. In these bands the resonance is localized on rotational levels with specific J and K values. As a consequence, a few transitions of the perpendicular bands involving the interacting levels could be identified in the spectra. A simultaneous fit of the transitions assigned to the dyads has been performed and the parameters of the excited states have been determined, including the high order Coriolis interaction coefficient . The anharmonic constants x₁₁, x₂₂, x₃₃ of all the studied isotopologues of FClO₃, x₄₆ of F³⁵Cl¹⁶O₃, x₄₆ + g₄₆ of F³⁷Cl¹⁶O₃ and x₁₆ of F³⁷Cl¹⁸O₃, have been derived.     

The rotational spectrum of BiO radical in its X1Π1/2 and X2Π3/2 states

Rotational spectra have been observed for BiO produced in a DC discharge through a low pressure mixture of O₂, Ar, and Bi vapor. Because of the highly non-thermal distribution of states, it has been possible to observe spectra arising from the X₁²Π_1/2 level up to v = 9 and for the X₂²Π_3/2 level up to v = 5 near 10 538 cm⁻¹. Precise rotational and hyperfine parameters have been determined for the observed states. By using available near infrared (NIR) data in a merged fit, the 0-0 and 1-1 fine structure intervals have been more precisely determined. Although the quality of the fit is very good, the interpretation of the hyperfine constants is complicated by relativistic effects and the interaction of the X₂ state with A₁⁴Π_3/2 state. The magnetic and quadrupole coupling constants will be compared with those of the Bi atom and related molecules.     

Submillimeter-wave spectroscopy of VN (XΔr) and VO (XΣ): A study of the hyperfine interactions

The pure rotational spectra of VN (X³Δ_r) and VO (X⁴Σ⁻) have been recorded in the frequency range 290-520 GHz using direct absorption spectroscopy. These radicals were synthesized in the gas-phase from the reaction of VCl₄ with either N₂ or H₂O in an AC discharge. Seven rotational transitions were recorded for each molecule; in both sets of spectra, fine and hyperfine structures were resolved. The data sets for VN and VO were fit with Hund’s case (a) and case (b) Hamiltonians, respectively, and rotational, fine structure, and hyperfine constants determined. For VN, however, an additional hyperfine parameter, Δa, was necessary for the analysis of the Ω = 2 sublevel to account for perturbations from a nearby ¹Δ state, in addition to the usual Frosch and Foley constants. Determination of Δa suggests that the ¹Δ state lies ∼3000 cm⁻¹ above the ground state. In VO, the hyperfine structure in the F₂ and F₃ components was found to become heavily mixed due to an avoided crossing, predicted by previous optical studies to be near the N = 15 level. The hyperfine constants established for these two molecules are consistent with the proposed σ¹δ¹ and σ¹δ² electron configurations.     

Mobility of positrons in silicon

The drift velocity v₊ of positrons in Si has been measured by observing the Doppler shift of the annihilation γ's. The electric field dependence of v₊ yields the positron mobility μ₊: at 80 K μ₊=460±20 cm²V^-1 sec^-1 and at 184 K μ₊=173±15 cm²V^-1 sec^-1.     

Laser magnetic resonance of the O2 molecule at 699 μm

A new highly sensitive far infrared optically pumped laser magnetic resonance (LMR) spectrometer has facilitated the observation of 21 transitions in O₂ at 699 μm (428.6285 GHz). All of these transitions involve N = 3 ← 1 of the oxygen molecule in its electronic ground state, X³Σ_g⁻. Of these 21 lines, 10 are due to the ¹⁶O₂, v = 0; 5 are due to the ¹⁶O₂, v = 1; 5 are due to the ¹⁶O¹⁸O, v = 0; and 1 set of 6 hyperfine components is due to the ¹⁶O¹⁷O, v = 0. From the intensity of the observed lines the sensitivity limit of this LMR spectrometer is found to be about 10⁻⁹ cm⁻¹ at this frequency with a 1-sec time constant.     

The Fundamental Bands in the Infrared Spectrum of Stibine (SbH3)

The infrared spectrum of stibine, SbH₃, has been recorded in the regions between 720 and 1000 cm^-1 and between 1750 and 2020 cm^-1 at a resolution of about 0.004 cm_-1. Rovibrational transitions belonging to the ν₂, ν₄ bending and ν₁, ν₃ stretching fundamental bands have been measured and assigned for both ¹²¹Sb and ¹²³Sb isotopomers. Strong perturbations due to rovibrational interactions have been observed both in the bending and in the stretching bands. Splittings of the K″=3, 6, and 9 lines have been observed and perturbation-allowed transitions with selection rules Δ (k−?)=±3, ± ±6, and ±9 have been also identified. Simultaneous analyses of transitions belonging to the ν₂/ν₄ or ν₁/ν₃ dyads have been performed. The central frequencies of the hyperfine structures of the rotational transitions in the v₂=1 and v₄=1 states, recorded in the microwave region by Fourier transform spectroscopy [H. Harder, C. Gerke, and L. Fusina, J. Chem. Phys.114, 3508-3523 (2001)], have been included in the data set. The theoretical model adopted explicitly takes into account the Coriolis interactions between the v₁=1 (A₁) and v₃=1 (E) and between the v₂=1 (A₁) and v₄=1 (E) states, including also several essential resonances within them.     

High order vibrational matrix elements for diatomic molecules; dipole moment function and transition moments of CO

The fifth and sixth-order contributions to the vibrational matrix elements are obtained for the transitions v→v'(v'?v+4) using an eight power internuclear Dunham potential and a quartic power series expansion of the dipole moment function. The results for the dipole moment coefficients M₀ to M₄ of CO and the transition moments R_v^v' (with v=5, 10, 20) deduced from a calculation including succesively third, fourth, fifth and sixth-order perturbation theory are compared. The validity of these results is discussed.Using a quintic dipole moment function, general expressions for the vibrational matrix elements corresponding to the transitions v→v'(v'? v+5) are also presented and the influence of these contributions on the calculation of the dipole moment coefficients as well as the hot band transition moments of CO is shown.     

Nuclear hyperfine structure in the XΣ state of ZrC

Electronic band systems of zirconium monocarbide, ZrC, in the 16 000-19 000 cm⁻¹ region have been observed following the reaction of laser-ablated Zr atoms with methane under supersonic free-jet conditions. Rotational analyses of high-resolution spectra have shown that the ground state of ZrC is a ³Σ state, with r₀=1.8066 Å and an unexpectedly small spin-spin parameter, λ=0.5139 cm⁻¹. The spectra are dense because of the five naturally occurring isotopes of Zr. Four of these, with mass numbers 90, 92, 94, and 96, have I=0, but the fifth, ⁹¹Zr, present in 11.22% abundance, has I=5/2. Lines of ⁹¹ZrC can be assigned in some of the strongest bands, and are found to display sizeable hyperfine splittings, with widths of up to 0.2 cm⁻¹. Analysis shows that the largest hyperfine effects are in the ground state, where b=−0.03133±0.00015 cm⁻¹ and c=−0.00123±0.00037 cm⁻¹ (3σ error limits). The large Fermi contact parameter, b, indicates that an unpaired Zr 5sσ electron is present, which, taken together with the small value of λ, means that the ground state must be a ³Σ⁺ state, from the electron configuration (Zr 5sσ)¹ (C 2pσ)¹. Internal hyperfine perturbations occur between the F₁ and F₃ electron spin components of the ground state in the range N=2-4, producing extra lines in some of the branches; the perturbations are of the type ΔN=0, ΔJ=±2, and are a second-order effect arising because the F₁ (J=N+1) and F₃ (J=N−1) spin components both interact with the F₂ (J=N) component through ΔN=0, ΔJ=±1 matrix elements of the Fermi contact operator. Second-order perturbations of this type can only occur in states that are very close to case (b) coupling.     

Die Hyperfeinstrukturaufspaltung des Grundzustandes2 S 1/2 und das magnetische Kerndipolmoment von Au197

The hyperfine structure of the groundstate 6s ² S _1/2 and the nuclear magnetic dipole moment of gold 197 have been studied by the atomic beam magnetic resonance technique. A special high frequency arrangement is described. The hyperfine structure separationΔ v was determined fromΔF=1 transitions. The magnetic dipole momentμ _I was measured by a direct method. The experiments yield the following results:Δv (²S_1/2)=(6099,309±0,010) Mc/secμ _I (Au¹⁹⁷)=+(0,1445±0,0014)μ _K.     

Precision infrared spectroscopy in CF379Br by means of infrared-microwave double resonance

From the observation of double resonance effects on the microwave spectrum two coincidences between 9.4 μm CO₂ laser lines and infrared transitions of the ν₆ → (ν₆ + ν₁) band of CF₃⁷⁹Br have been determined: R(30) laser line coincident with ^qR₂(7), F = 17/2→17/2 transition, R(28) laser line coincident with all four ΔF = 0 hyperfine components of the ^qQ₈(13) transition. In both cases other infrared transitions lay within the tuning range of the laser. The frequencies of these two laser lines allowed calculations of the band center frequency ν₀ = 1083.530 ± 0.001cm^?1 and α_A = 11.93 ± 0.3MHz, for the ν₆ → (ν₆ + ν₁) band.α_B constants were determined for the vibrational states v₆, (v₆ + v₁), v₁, and v₃.     

Hyperfine structure in the BΠ0u state of Br2 and the influence of the perturbing 1u state

Using Doppler-free polarization spectroscopy, the hyperfine structure of the B-X system of ⁷⁹Br₂ was measured for the levels B³Π_0⁺u, v′ = 16–28, and X¹Σ_g⁺, v″ = 1, 2. Besides the nuclear electric quadrupole coupling, the magnetic spin-rotation interaction was analyzed, which varies strongly with the vibrational energy of the electronically excited state. This behavior originates from a perturbing repulsive state Ω = 1_u, the potential of which can be estimated in this way.     

Mössbauer and infrared studies of the Cu-Cr ferrites

Ferrites of the system CuCr_xFe_2–x O₄, wherex=0,0.2,0.4, 0.6 and 0.8, have been studied by Mössbauer and IR absorption spectra. Mössbauer spectra were recorded at room temperature. The spectra of all samples showed two well defined Zeeman patterns corresponding to A and B sites. The effect of the variation of chromium substitution on the various hyperfine interactions has been discussed. The cationic distribution makes clear that all Cr³⁺ ions occupy octahedral sites. The IR spectra in the range 200–4000 cm^–1 showed the presence of four bands. The high and low frequency bandsv ₁ andv ₂ belong to the tetrahedral and octahedral sites, respectively. Small bandsv ₃ andv ₄are observed around v₂ and are assigned to the octahedral divalent metal-oxygen ion complexes and the lattice vibrations of the system, respectively.     

Zur Rumpfpolarisation des Rb-Atoms: Hyperfeinstruktur des 72 P 1/2-Terms von Rb85

The hyperfine structure splitting of the 7² P _1/2 state of Rb⁸⁵ has been investigated with optical double resonance spectroscopy. The results are:v _F=3?F=2=52.95(6) Mc/s,A _J=1/2=17.65(2) Mc/s,g _J (7² P _1/2, Rb)=0.6668(1). From the hfs interaction constants of the 7² P multiplett a 12% core polarization contribution to the magnetic hfs of the 7² P _3/2 state can be deduced. Comparison is made between the values of 〈r ^?3〉 calculated from either the magnetic hfs or the² P fine structure separation.     

Predissociation linewidths and oscillator strengths for the (2-0) to (13-0) Schumann-Runge bands of O2

Analysis of the absorption spectrum of O₂ in the Schumann-Runge bands (B³Σ_u^?-X³Σ_g^?) from the 2-0 to the 13-0 band yields oscillator strengths which are in good agreement with past theoretical calculations. Predissociation linewidths deduced from the data tend to be larger than theoretical predictions for v′ ≤ 5 and are reasonably near theory for v′ > 5. The qualitative dependence of the linewidths on vibrational level is in accord with that expected for a repulsive potential intersecting the B³Σ state near v′ = 4. For a given band the predissociation linewidth deduced from the spectra tends to increase as the total angular momentum increases. The new linewidths are smaller than some past experimental results, and this will have an impact on future calculations of the photodissociation rates of O₂, NO, and H₂O in the earth's upper atmosphere.     

12C16O2: Σ and Π Fermi dyads in the 4.5-μm region: Wavenumbers and spectroscopic constants

Emission spectra of CO₂ vibrationally excited by a dc electric discharge were recorded under Doppler-limited resolution, using the high information interferometer of Laboratoire d'Infrarouge Orsay, France, in the spectral region 4–5 μm. Sixteen bands with Δv₃ = 1 of ¹²C¹⁶O₂ involving the Fermi dyads (10⁰v₃, 02⁰v₃)_{I and II} and (11¹v₃, 03¹v₃)_{I and II} have been studied. The band centers and the spectroscopic constants for all the vibrational levels involved are given. They reproduce the experimental wavenumbers with a rms of the order of 4 × 10^?5 cm^?1 for the best vibrational transition and always less than 3 × 10^?4 cm^?1 for the others. These results are compared with laser measurements for the (10⁰0, 02⁰0) dyad.     

Analysis of the ground configuration of Tm3+ in YVO4

An analysis has been made of the optical spectrum of Tm³⁺ in YVO₄ reported by K. D. Knoll. The approach taken was to describe the Tm³⁺ free ion as completely as possible and then to describe the effects of the crystal field on these levels. Parameters were obtained that gave an r.m.s. deviatioa of 10.6 cm^?1 in a least squares fit. In Knolls' earlier analysis, which did not describe the free ion adequately, several sets of parameters were given that are consistent with different portions of the spectrum. The results computed with our parameters gave a new interpretation of the ³F₄ and ³H₅ multiplets and gave g_∥ factors in good agreement with the measurements. The efiects of the hyperfine interaction and the spin-crystal field interaction on the energy levels resulted in displacements of smaller than 0.1 cm^?1.