Rotational analysis and radiative lifetime measurement on the 2B1 (K′ = 0) excited state of NO2 with v′2 = 6, 7, 8, and 9

The rotational structure of the ²B₁ (K′ = 0) subbands of NO₂ with v′₂ = 6, 7, 8, and 9 were analyzed by means of the time-gated excitation spectrum. The excitation spectrum monitored at ν₂, 2ν₂, or 3ν₂ fluorescence band was fairly simplified in comparison to its corresponding absorption spectrum. The band origins and rotational constants are evaluated from the observed data: ν₀ = 20205.0 cm^?1, $\text{B}\text{′ = 0.374}\text{cm}{}^{\mathrm{?1}}$ for v′₂ = 6; ν₀ = 21104.4 cm^?1, $\text{B}\text{′ = 0.374}\text{cm}{}^{\mathrm{?1}}$ for v′₂ = 7; ν₀ = 22001.9 cm^?1, $\text{B}\text{′ = 0.375}\text{cm}{}^{\mathrm{?1}}$ for v′₂ = 8ν₀ = 22898.0 cm^?1, $\text{B}\text{′ = 0.375}\text{cm}{}^{\mathrm{?1}}$ for v′₂ = 9. The value of $\text{B}\text{′}$ extrapolated to v′ = 0 is 0.370 cm^?1. This value corresponds to the bond length of 1.19 Å. Fluorescence decays of these excited levels were also studied. Radiative lifetimes obtained by extrapolation to zero pressure from the $\text{1}\text{τ}\text{– P}$ plots were 25–40 μsec. The short-lived excited levels previously reported by some authors were not found.     

Dependence of nuclear deorientation on nuclear spin for recoils in vacuum

Time-integral measurements have been made of the vacuum deorientation of the 2⁺ and 4⁺ states in ¹⁵⁰Sm and the 6⁺ and 8⁺ states in ¹⁵⁶Gd Coulomb-excited by 133 MeV ³⁵Cl ions. The ¹⁵⁰Sm results were deduced from γ-ray angular distributions measured in coincidence with backscattered ³⁵Cl ions. In the ¹⁵⁶Gd measurements, a fixed counter array and a sandwich target were used to measure directly the differences between the γ-ray angular distributions from nuclei recoiling in vacuum and the unperturbed γ-ray angular distributions from nuclei stopped in a thick ¹⁵⁶Gd target. The measured deorientation time constants in ps are τ₂(2⁺) = 27±4; τ₂(4⁺) = 14±4; τ₂(6⁺) = 24±3; τ₂(8⁺) = 23⁺¹⁰_?6; τ₄(2⁺) = 12±2; τ₄(4⁺) = 5±3; τ₄(6⁺) = 7.6±2.5. The 8⁺ data were analyzed assuming τ₂/τ₄ = $\text{10}\text{3}$ as predicted by the Abragam-Pound theory for $\text{I ≧ 4}$ essentially independently of the degree of quadrupole admixture. The other results are consistent with this except for the 2⁺ level which shows some quadrupole effect. The present results, which show strong deorientation of high spin levels, are in contrast to earlier work on neutron deficient Er isotopes. In light of our findings we suggest that the failure to observe deorientation in the high spin states in Er is primarily due to anomalously low g-factors associated with the backbending observed in these nuclei.     

The microwave spectrum,structure, and quadrupole coupling constants of boron chloride difluoride,BCIF2

The microwave spectrum of boron chloride difluoride, BClF₂, has been investigated in the region 26.5–40.0 GHz. R-branch transitions belonging to the isotopic species ¹¹B³⁵Cl¹⁹F₂, ¹¹B³⁷Cl¹⁹F₂, and ¹⁰B³⁵Cl¹⁹F₂ have been observed and the derived rotational constants yield the following ground-state structural parameters: $\text{r}{}^0\text{(BF) = 1.315 ± 0.006}\text{A}\text{?}$, $\text{r}{}^{\mathrm{s}}\text{(BCl) = 1.728 ± 0.009}\text{A}\text{?}$, < FBF = 118.1 ± 0.5°. The ground-state rotational constants of the most abundant species ¹¹B³⁵Cl¹⁹F₂ are: A₀ = 10 449.32 ± 0.13, B₀ = 4705.811 ± 0.020, C₀ = 3239.702 ± 0.026 MHz, Δ_JK = 8.9 ± 1.7, and Δ_J = 1.86 ± 0.48 KHz. The asymmetry parameter κ = ?0.593291 and the inertial defect δ⁰ = 0.2361 amu Ų which is consistent with that expected for this type of molecule if planar. The ³⁵Cl quadrupole coupling constants for ¹¹B³⁵Cl¹⁹F₂ are χ_aa = ?42.8 ± 1.0, χ_bb = 30.2 ± 1.5, χ_cc = 12.6 ± 1.5 MHz with the asymmetry parameter η = 0.41.     

Trapping probabilities and desorption energies of alkali atoms on a clean and an oxygen covered tungsten (110) surface

Alkali atoms were scattered with hyperthermal energies from a clean and an oxygen covered (θ ≈ 0.5 ML) W(110) surface. The trapping probability of K and Na atoms on oxygen covered W(110) has been measured as a function of incoming energy (0–30 eV) and incident angle. A considerable enhancement of trapping on the oxygen covered surface compared to a clean surface was observed. At energies above 25 eV there are still K and Na atoms being trapped by the oxygen covered surface. From the temperature dependence of the mean residence time τ of the initially trapped atoms the pre-exponential factor τ₀ and the desorption energy Q were derived using the relation: $\text{τ = τ}{}_0\text{exp}\text{(}\text{Q}\text{kT}{}_{\mathrm{<mtext>s</mtext>}}\text{)}$. On clean W(110) we obtained for Li: $\text{τ}{}_0\text{= (8 ±}\text{8}\text{4}\text{) × 10}{}^{\mathrm{?14}}\text{sec}$, Q = (2.78 ± 0.09) eV; for Na: τ₀ = (9 ± 3) × 10^?14 sec, Q = (2.55 ± 0.04) eV; and for K: τ₀ = (4 ± 1) × 10^?13 sec, Q = (2.05 ± 0.02) eV. Oxygen covered W(110) gave for Na: τ₀ = (7 ±3) × 10^?15 sec, Q = (2.88 ± 0.05) eV; and for K: $\text{τ}{}_0\text{= (1.3 ±}\text{0.9}\text{0.6}\text{) × 10}{}^{\mathrm{?14}}\text{sec}$, Q = (2.48 ±0.05) eV. The adsorption on clean W(110) has the features of a supermobile two-dimentional gas; on the oxygen covered W(110) adsorbed atoms have the partition function of a one-dimen-sional gas. The binding of the adatoms to the surface has a highly ionic character in the systems of the present experiment. An estimate is given for the screening length of the non-perfect conductor W(110):k_s^?1≈ 0.5 Å.     

Evidence for two narrow pp resonances at 2020 MeV and 2200 MeV

From the study of the reaction $\text{π}{}^{\mathrm{?}}\text{p→p}{}_{\mathrm{F}}\text{p}\text{p}\text{π}{}^{\mathrm{?}}$ using a fast proton (p_F) trigger device in the CERN Omega spectrometer, we find evidence for two narrow $\text{p}\text{p}$ states produced mainly in association with a Δ° (1232) and a N° (1520). The statistical significance of each peak is greater than 6 standard deviations. Masses and natural widths of these resonances are respectively M = 2020 ± 3 MeV, Λ₁ = 24 ± 12 MeV and M₂ = 2204 ± 5 MeV, Λ₂ = 16_?16⁺²⁰ MeV. Our data are consistent with a small production of the narrow ～ 1935 MeV resonance already reported. Production cross sections for these new $\text{p}\text{p}$ resonances are given.     

Crystal field parameters and phase transitions in ErSb

The crystal field levels of the Er ($\text{J =}\text{15}\text{2}$) ion in a single crystal of ErSb have been measured by inelastic neutron scattering. The crystal field parameters obtained by a least squares fit to the spectra at several temperatures are: B₄ = (0·473 ± 0·005) × 10^?2°K and B₆ = (0·59 ± 0·06) × 10^?5°K, which differ considerably from the values o by interpolation from measurements on other compounds. In addition the temperature dependence of the magnetic scattering in the vicinity of the Néel temperature (T_N = 3·55°K) clearly demonstrates that the transition is second order in contrast to the first order behavior suggested by specific heat measurements. Also, any lattice distortion accompanying the magnetic ordering is less than 0.1 per cent, the resolution of the present experiment.     

Study of the (p,pn) reaction in light nuclei

The (p, pn) reaction on ²H, ⁶Li, ⁷Li, ⁹Be has been studied at 47 MeV bombarding energy. Excitation energy spectra and energy sharing spectra are presented. Fragmentary information on ¹⁰B, ¹¹B and ¹²C was also obtained. Sequential decay contributions to the ⁶Li(p, pn)⁵Li¹ reaction suggest an admixture of parentage $\text{(α)π(}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)π(}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}$ for the (3^?), 23 MeV excited state of ⁶Be. A possible 15.5 MeV excited state in ⁶Be is reported. An extensive study of the ⁹Be (p, pn)⁸Be reaction for 45 MeV protons was made. Results for θ_p = θ_n = 25°, 30°, 35°, 40°, 45°, 55°, 65°; θ_n = 40°, θ_p = 25°, 30°, 35°, 40°, 45°, 55°, 65°; θ_p/θ_n = 40°/45°, 38.5° are reported and compared to DWIA calculations. Agreement is good when the lower momentum components of the wave function are sampled, and deteriorates as higher momenta are required. Results are in agreement with the Cohen and Kurath spectroscopic factors for ⁹Be.     

Laser-induced fluorescence spectrum of nitrogen dioxide in the neighborhood of 6125 Å

The resonance fluorescence spectrum of nitrogen dioxide has been excited by a tunable, cw dye laser in the neighborhood of 6125 Å. The rotational constants of the ²B₂ upper electronic state are determined as follows, in units of cm^?1: A_v′ = 7.2 ± 0.6; $\text{B}\text{?}{}_{\mathrm{v}}\text{′ = 0.454 ± 0.015}$; B_v′ = 0.496 ± 0.046; C_v′ = 0.412 ± 0.019. The band origin is at 16 325.1 ± 1.8. Quoted error limits are standard deviations obtained from the fit of the data. The vibrational assignment of the upper state is (0, 5, 0), and by combination with the data of other workers, we estimate for its vibrational constants, in cm^?1: ω₁′ + x₁₁′ = 1425.7; ω₂′ = 876.6; x₂₂′ = ?0.83; x₁₂′ = ?8.1. The molecular geometry in the upper state is briefly discussed.     

Evidence for a narrow peak in Ksoπ±π+π- at 2.6 gev in 12 gev/cpp interactions

We report the evidence for a narrow charged peak (5.5 s.d.), which we suggest calling the I, in the 6-prong-V⁰ topology of $\text{p}$p interactions at 12 GeV/c. The mass, widht and the product of cross section σ_I times the branching ratio BR into the final state (K_s^oτ±τ⁺τ^? are found to be: $\text{M}{}_{\mathrm{I}}\text{=2.60 ±}\text{0.01}\text{GeV}\text{/}\text{c}{}^2$, $\text{Γ}{}_{\mathrm{I}}\text{?}\text{0.018}\text{GeV}\text{/}\text{c}{}^2$, σ_I·BR≈20 μbarn     

Mixed conduction in Cr-doped GaAs

Hall-effect and magnetoresistance measurements have been carried out in GaAs : Cr as functions of magnetic field strength (B = 0–18kG) and temperature (T = 125–420°K). Independent solutions for the mobilities, μ_n and μ_p, and the carrier concentrations, n and p, are obtained from the basic mixed-conductivity equations. These quantities, as well as the intrinsic carrier concentration, n_i are then calculated as a function of temperature for one sample, and subsequent analysis yields the following values in the range T = 360–420°K: an acceptor (presumably Cr) energy E_A = 0.69±0.02eV (from the valence band); the bandgap energy E_g = E_g0 + αT, with E_go = 1.48±0.02eV, $\text{α ? 3.2 × 10}{}^{\mathrm{?4}}\text{eV}\text{°}\text{K}$; $\text{μ}{}_{\mathrm{n}}\text{= 2700± 100}\text{cm}{}^2\text{V}\text{sec}$, decreasing slightly with temperature; = 350± 50 $\text{cm}{}^2\text{V sec}$; and an acceptor-to-donor concentration ratio, itN_A/N_D?8. The electron mobility appears to be limited by neutral impurity scattering, with N_A ? 2 × 10¹⁶cm^?3. Several other samples were also investigated but as a function of temperature only (at B = 0). At room temperature both positive (p-type) and negative (n-type) Hall coefficients were observed.     

Depolarization in proton inclusive inelastic scattering and in the (d,p) reaction on medium-weight nuclei

The energy-averaged depolarization parameter K_y^y′ has been measured for the inelastic scattering of 18 MeV protons from ⁵⁴Fe, ⁶³Cu and ⁹²Mo at 45°, 90° and 135°, and for 14.35 MeV protons from ⁶³Cu at 45° and 135°. In all cases K_y^y′ varies from approximately unity for scattering with low energy loss to approximately zero for inelastic scattering to high excitation energies. The change from one of these values to the other occurs over a region ≈ 6 MeV wide centered at about 5 MeV excitation. A simple two-component model fits both the K_y^y′ and inelastic crosssection data. K_y^y′ has also been measured for the ⁵⁴Fe($\text{d}$, $\text{p}$)Fe reaction with 16 MeV deuterons incident. Here K_y^y′ changes from approximately the maximum possible value, $\text{2}\text{3}$, to about zero in a 6 MeV region centered at roughly 13 MeV excitation. The ($\text{d}$,$\text{p}$) data can be fitted by an extension of the model used for the proton scattering data.     

Microwave optical double resonance and continuous wave dye laser excitation spectroscopy of NO2: Rotational assignment of the K = 0−4 subbands of the 593 nm band

A rotational assignment of approximately 80 lines with K_a′ = 0, 1, 2, 3, and 4 has been made of the 593 nm ${}^2\text{A}{}_1\text{→}{}^2\text{B}{}_2$ band of NO₂ using cw dye laser excitation and microwave optical double-resonance spectroscopy. Rotational constants for the ²B₂ state were obtained as A = 8.52 cm^?1, B = 0.458 cm^?1, and C = 0.388 cm^?1. Spin splittings for the K_a′ = 0 excited state levels fit a simple symmetric top formula and give $\text{(?}{}_{\mathrm{bb}}\text{+ ?}{}_{\mathrm{cc}}\text{)}\text{2}\text{= ?0.0483}\text{cm}{}^{\mathrm{?1}}$. Spin splittings for K_a′ = 1 (N′ even) are irregular and are shown to change sign between N′ = 6 and 8. Assuming that the large inertial defect of 4.66 amu Ų arises solely from A, a structure for the ²B₂ state is obtained which gives $\text{r}\text{(NO) = 1.35}\text{A}\text{?}$ and an ONO angle of 105°. Alternatively, weighting the three rotational constants equally gives $\text{r = 1.29}\text{A}\text{?}$ and θ = 118°.     

Transition probabilities in the doubly odd nuclei 176Lu and 182Ta

The depopulation of isomeric states in ¹⁷⁶Lu and ¹⁸²Ta was studied in the (n, γ) reaction by means of delayed γ-γ coincidence measurements with NaI(Tl) and Ge(Li) detectors. The following half-lives, unknown so far, have been obtained for ¹⁷⁶Lu: $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(198.0}\text{keV}\text{) = 35.0 ± 1.0}\text{ns}$, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(638.8}\text{keV}\text{) = 8.0±1.0}\text{ns}$ and $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(662.1}\text{keV}\text{) = 6.3±0.5}\text{ns}$; and for ¹⁸²Ta: $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(270.4}\text{keV}\text{) = 1.2 ± 0.2}\text{ns}$, $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(402.6}\text{keV}\text{) = 1.00 ± 0.05}\text{ns}$ and $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(443.6}\text{keV}\text{) = 2.2 ± 0.2}\text{ns}$. The existence of the isomeric level at 443.6 keV in ¹⁸²Ta was confirmed. Weisskopf hindrance factors have been deduced for the K- and Ω-forbidden transitions. The K-allowed transitions are considered in terms of the Nilsson model taking into account pairing correlations. The experimental results for the transitions de-exciting the 270.4 keV level in ¹⁸²Ta agree with earlier model predictions including band mixing effects. The influence of the pairing effect on K-allowed E1 transitions in doubly odd nuclei is demonstrated.     

Polymorphism of InS at high pressures

In situ X-ray diffraction has been used to study high-pressure polymorphism of InS up to ～ 13 Gpa in the 293–573 K temperature range. The phase transition InS I?arr2;InS II is found under isothermal compression at p_t = 7.5 ± 0.5 GPa and T = 293 K; at p_t = 6.0 ± 0.5 GPa and T = 573 K. InS II crystallizes in the structural type of Hg₂Cl₂: $\text{a = 3.823 ± 0.008}\text{A}\text{?}$; $\text{c = 10.868 ± 0.030}\text{A}\text{?}$; c/a = 2.843; Z = 4; D_4h¹⁷(I4/mmm); V_p/V₀ = 0.85; p = 10 GPa, T = 293 K. X-ray powder data indicate a continuous change of the orthorhombic structure of InS I with increasing pressure associated with the transition to the tetragonal phase InS II.     

Longitudinal polarization transfer in the T→p, →n)3He reaction

The longitudinal polarization of neutrons has been measured for the reaction $\text{T}\text{→p}\text{,}\text{→n}\text{)}{}^3\text{He}$ with the incident proton beam longitudinally polarized. Measurements were performed at 0° for proton energies from 4 to 15 MeV and an angular distribution was measured at 10 MeV. The data determine the polarization transfer coefficient K_z^z′, which is equivalent to the Wolfenstein A′ parameter for nucleon-nucleon scattering. The quantity K_z^z′ at 0° increases from about 0.3 at 3 MeV incident energy to 0.9 at 9 MeV, and then decreases to 0.5 at 15 MeV. The data are computed with R-matrix calculations which reproduce the qualitative shape of the data at 0° and the angular distribution at 10 MeV.     

Alpha-particle decay of 218Th,a new isotope

A new isotope, ₉₀²¹⁸Th₁₂₈, has been found to decay with E_α = 9.67 ± 0.02 MeV and $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 96 ± 7}\text{ns}$. The reduced α-particle width of ²¹⁸Th is about 1.4 times the value expected from the general trend of the N = 128 isotones with Z = 84?89.     

Determination of A0 for CH335Cl and CH337Cl from the ν4 infrared and Raman bands

The ν₄ infrared and Raman bands of CH₃Cl were analyzed simultaneously. A direct fit yielded a complete set of constants for CH₃³⁵Cl, including A₀ = 5.20530 ± 0.00010 cm^?1 and D_K = (8.85 ± 0.13) × 10^?5cm^?1. For CH₃³⁷Cl an incomplete set of constants was obtained from the infrared band, and A₀ = 5.2182 ± 0.0010 cm^?1 was estimated by curve fitting of the Raman spectrum. The resulting equilibrium structure is $\text{r(}\text{CH) = 1.0854 ± 0.0005}\text{A}\text{?}$, $\text{r(}\text{CCl) = 1.7760 ± 0.0003}\text{A}\text{?}$, and <(HCH) = 110°.35 ± 0°.05.     

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     

The visible and photographic infrared spectrum of osmium oxide

The emission spectrum of OsO has been photographed in the region 405–875 nm where many new bands have been observed. In favorable cases the ${}^{190}\text{OsO}{}^{192}\text{OsO}$ isotopic splittings have been resolved and aid in vibrational assignments. Three visible bands in the region 433–470 nm have been assigned as (1,0), (0,0), and (0,1) of a $\text{ΔΩ}\text{= 0}$ electronic transition. The (0,0) and (0,1) bands have been rotationally analyzed, yielding principal constants (cm^?1) for the visible system of ν₀ = 22 273.3, B′₀ = 0.3657, D′₀ = 2.8 × 10^?7, B″_e = 0.4023, D″_e = 3.2 × 10^?7, $\text{Δ}\text{G″(}\text{1}\text{2}\text{) = 780.7}$, and $\text{Δ}\text{G″(}\text{1}\text{2}\text{) = 884.9}$. A band at 825.4 nm has been found to be a $\text{ΔΩ}\text{= +1}$ (0,0) band with the same lower state as in the analyzed visible bands. Constants for the upper state of the ir system are ν₀ = 12 109.7, B′₀ = 0.3845, and D′₀ = 3.1 × 10^?7 cm^?1.     

Search for long-lived particles in 200 GeV/c proton-nucleon collisions

A search for long-lived particles (τ ? 10^?8 sec), with changes $\text{±}\text{2}\text{3}\text{, ± 1, ±}\text{4}\text{3}\text{and}\text{± 2}$, produced in 200 GeV pN collisions was performed at the CERN-SPS in a secondary beam equipped with superconducting r.f. separators. Upper limits were obtained for the production of long-lived hadrons and leptons. For charge - 1 particles the limits are at the level of 10^?7 of the pions at a mass m = 0.2 GeV and reach the 10^?11 level from $\text{3}\text{to}\text{8}\text{GeV}$. The production of light antinuclei was measured. The cross sections for ³He production are (1.3 ± 0.3) and (1.9 ± 0.3) × 10^?34 cm²/sr · GeV/c at 21 and 47.4 GeV/c respectively; for t the cross section is (7.6 ± 0.9) × 10^?34 cm²/sr · GeV/c at 23.7 GeV/c.