Energies of the n2S12 and n2D32,52 states of Cs

Using the technique of Doppler-free two-photon spectroscopy the energies of the n²S_{$\text{1}\text{2}$} (12 ? n ? 35) and n²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} (11 ? n ? 48) states of CsI have been measured with a thermionic detector. The absorption spectrum of molecular iodine was used as a reference giving us a total estimated accuracy of about 2 × 10^-7. Taking also into account the energies of the 7–11 ²S_{$\text{1}\text{2}$} and 5 and 6 ²D_{$\text{3}\text{2}$,$\text{5}\text{2}$} states measured by other authors and using an extended Ritz-formula we found the ionization limit to be E_i = 31406.468 ± 0.006 cm^-1.     

Polarization transfer in the 2H(d,n)3He reaction at θ = 0°

The vector polarization transfer coefficient K_y^y′ and the tensor analyzing power A_zz have been measured for the ²H($\text{d}$$\text{n}$)³He reaction at θ = 0° over an incident deuteron energy range from 1 to 15 MeV in 0.5 MeV steps. The results agree with the previous ²H($\text{d}$$\text{n}$)³He measurements of Simmons et al. and are nearly identical to the ²H($\text{d}$$\text{n}$)³H measurements of Clegg et al. in the region of overlap. The present results provide an accurate and complete set of the observables necessary to use the ²H($\text{d}$,$\text{n}$)³He reaction as a source of polarized neutrons.     

The reaction 55Mn(d, t)54Mn

Neutron pick-up cross sections and vector analyzing powers have been measured for the reaction ⁵⁵Mn($\text{d}$, t)⁵⁴Mn at 17 MeV. The mixture of $\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ to $\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ transfer to the low-lying l_n = 1 states has been found. Evidence of the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ hole nature of several strong l_n = 3 states above 1 MeV has been obtained.     

S12-P12-lambshift in the n = 5 and n = 6 states of ionized helium

The S_{$\text{1}\text{2}$}-P_{$\text{1}\text{2}$}-splittings in the n = 5 and n = 6 states of He⁺ have been determined by an r.f. method to be (905.2 ± 1.0) MHz and (526.7 ± 2.5) MHz, respectively (theory: 906 and 524.2 MHz). The electric fields in the resonance cell and their dependence on the experimental parameters have been examined.     

Evidence for assignment of 14.0 MeV state in 11B from 10B(n,n)10B

The differential cross section and polarization for neutrons scattered from ¹⁰B have been measured at E_n = 2.63 MeV (E_x = 13.85 MeV). The results of this experiment and other available neutron scattering data in the range 1 < E_n < 4 MeV are interpreted through a single-level R-matrix calculation over the region 12 < E_x < 15 MeV. Based on this analysis the most probable J^π assignment for the 14.0 MeV level in ¹¹B is $\text{11}\text{2}{}^{\mathrm{+}}$. The anomaly near E_x = 13.1 MeV can only be explained in terms of two overlapping levels having assignments of ($\text{5}\text{2}$, $\text{7}\text{2}$)^? and ($\text{3}\text{2}$, $\text{5}\text{2}$, $\text{7}\text{2}$)⁺.     

Some studies of T = 32 states in 17F

Measurements have been made of some parameters of the second and sixth $\text{T =}\text{3}\text{2}$ states in ¹⁷F. For the second state, the resonance energy was found to be E_p = 12.707 ± 0.001 MeV (E_n = 12.550±0.001 MeV), which agrees with and improves on the accuracy of earlier work. For the sixth $\text{T =}\text{3}\text{2}$ state, at E_p = 14.435 MeV, the γ-decay was determined to be predominantly γ₀ with a branch to the first excited state of Γ(γ₁)/Γ(γ₀) ≦ 0.14. Together with other work, this determines J^π to be $\text{3}\text{2}{}^{\mathrm{?}}$. The capture strength is found to be (2J + 1)Γ_pΓ_γ/Γ = 11.4 ± 2.6 eV.     

On triviality of the :expλϕ:4 quantum field theory in a finite volume

The ?dν(λ):expλ?:_n (without counterterms) quantum field theory is considered. Here ν(·) is a finite positive measure.Let n ? 3, or n = 2 and supp$\text{ν ∩ [?}\text{8π}\text{,}\text{8π}\text{] = ?}$. Under these conditions the theory ?dν(λ):expλ?:_n (without counterterms)converges to the free-field theory when the cut- offs are removed.     

Relaxation of the 4G92 state of Nd3+ in LaCl3 and Nd3+ in La(Cl99.6Br0.4)3

The decay of the ⁴G_{$\text{9}\text{2}$} state of Nd³⁺ in LaCl₃ and La(Cl_99.6 Br_0.4)₃ was measured after pulsed laser excitation as a function of temperature. The decay rate is shown to depend besides the radiative transition on single-phonon relaxation between the states ⁴G_{$\text{9}\text{2}$} ($\text{μ =}\text{1}\text{2}$) and ⁴G_{$\text{9}\text{2}$} ($\text{μ =}\text{3}\text{2}$) and on multiphonon orbit-lattice relaxation from ⁴G_{$\text{9}\text{2}$} to ²G_{$\text{9}\text{2}$}. Partial substitution of Cl by Br only alters the radiative lifetime.     

A new ferroelectric compound: Methylammonium trichloromercurate (CH3NH3HgCl3)

Measurements of the dielectric constants revealed a ferro- to paraelectric transition in methylammonium trichloromercurate (CH₃NH₃HgCl₃). Thermal analysis by differential scanning calorimetry indicates a transition temperature of Tc ≈ 60°C. The structures of both phases were determined from single crystal X-ray measurements. The ferroelectric phase crystallizes at room temperature in the polar trigonal space group $\text{P}\text{3}{}_2\text{(a = b =}\text{7.8117(3)}\text{, c =}\text{9.826(3)}\text{A}\text{?}\text{, Z =}\text{3}\text{)}$. The refinement of the ferroelectric structure included the fractional contribution of the two domains present. The paraelectric phase has monoclinic symmetry (space group C2 with $\text{a =}\text{13.816(2)}\text{, b =}\text{7.880(1)}\text{, c =}\text{9.734(3)}\text{A}\text{?}\text{, β =}\text{90.49(5)°}\text{, Z =}\text{6}\text{)}$ and contains an almost completely disordered methylammonium group while order with pronounced thermal motion is observed in the ferroelectric phase.     

Lattice parameters variation with temperature of Ti2O3 and (Ti0.98V0.02)2O3 from single crystal X-ray data

The lattice parameters of Ti₂O₃ and (Ti_0.98V_0.02)₂O₃ have been measured as a function of temperature (24–670°C for Ti₂O₃ and 24–440°C for V-doped Ti₂O₃) from single crystal X-ray data. The high temperatures were attained by blowing hot argon directly on the crystal mounted on an automatic Philips diffractometer. This experimental set-up gives standard deviations which are at least 10 times better than those of the previous measurements and allows to keep Ti₂O₃ as such well above the transition. The variations of a, c, $\text{c}\text{a}$ (hexagonal axes) for pure Ti₂O₃ are in agreement with the previous results. On the contrary we did not observe any transition in the unit cell volume. The V-doping seems to attenuate the transition which is visible only on the a vs T curve     

The crystal structures of the ion conductors (NH+4)Zr2(PO4)3and (H3O+)Zr2(PO4)3

The crystal structures of (NH⁺₄)Zr₂(PO₄)₃ and (H₃O⁺)Zr₂(PO₄)₃ have been determined from neutron time-of-flight powder diffraction data obtained at 15 K. Both compounds are rhombohedral, $\text{R}\text{3}\text{c}$, with cell parameters a=8.7088(1) and c=24.2197(4) Å for the ammonium compound and a=8.7528(2), c=23.6833(11) Å for the hydronium compound. In both cases the ions are completely localized in the type I cavities and hydrogen bonded to lattice oxygens. The measured unit cell parameters are relatively large for this class of compounds but the entrance ways into the cavities are still too small to allow for unrestricted movement of the ions. Thus the low conductivity of the hydronium ion is related to this and other structural features.     

20Ne + n → 21Ne(T = 32) resonances

$\text{T =}\text{3}\text{2}$ resonances in ²¹Ne have been studied in measurements of the total neutron cross section of ²⁰Ne using the 190 m neutron time-of-flight facility of the Karlsruhe Isochronous Cyclotron. The high time-of-flight resolution of 6.6 ps/m enabled the study of sharp $\text{T =}\text{3}\text{2}$ resonances in ²¹Ne with an effective energy resolution of up to 4000. Five $\text{T =}\text{case3}\text{2}$ levels have been observed as sharp resonances allowing the precise determination of total width Λ, partial decay with Λ_no and resonance energy E_R. The c.m. resonance parameters of the first $\text{T =}\text{3}\text{2}$ state in ²¹Ne are E_R = 2098.6 ± 0.3 keV, Λ = 2.2 ± 0.5 keV and Λ_no = 0.21 ± 0.05 keV. Upper limits for the partial decay widths are deduced for those $\text{T =}\text{3}\text{2}$ levels which do not appear as resonance anomalies. A search for additional $\text{T =}\text{3}\text{2}$ states was undertaken. The resonance energies are discussed in the framework of the isbobaric mass multiplet equation. The decay widths are compared with shell-model predictions of isospin mixing and the systematics of isospin-non-conserving particle decays.     

The reaction π−p → ηn up to pη1 = 450 MeV/c: experimental results and partial-wave analysis

An accurate measurement of $\text{d}\text{σ}\text{d}\text{Ω}\text{(π}{}^{\mathrm{?}}\text{p}\text{→ η}\text{n}\text{)}$ at 1531 MeV total energy (expanded) up to l = 4 Legendre polynomials) requires reconsideration of previous angular distribution fits which were expanded only up to l = 2 and of subsequent partial-wave analysis. An energy-dependent partial-wave analysis has been performed here for $\text{p}{}_{\mathrm{\eta }}{}^1$ up to 450 MeV/c. In addition to the well-known S₁₁ (1520 MeV) resonance, either the P₁₁ (1532 MeV) or the P₁₃ (1530 MeV) resonance is found to be strongly coupled to the η-n channel. In both cases, the P₁₁ (1729 MeV) resonance is needed as is the weakly coupled D₁₃ (1525 MeV) resonance. The decay states in the ηn channelare compared to the SU(3) and SU(6)_W predictions.     

nπ1 Transitions in tetramethyl-1,3-cyclobutanedithione-h12 and -d12

The polarized low-temperature crystal absorption spectra of tetramethyl-1,3-cyclobutanedithione-h₁₂ and -d₁₂ have been measured in the visible region, and $\text{nπ}{}^1$ excited states identified as follows: ³A_u with origin ($\text{h}{}_{12}\text{d}{}_{12}$) at $\text{16 829}\text{16 836}\text{cm}{}^{\mathrm{?1}}$; ¹A_u and ¹B₁₀ with nearly degenerate origins near 18 000 cm^?1; and probably ¹A_u and ¹B_1g near 19 500 cm^?1. The singlet excited states lie close together and perturb each other strongly. As in the corresponding dione, $\text{CH}\text{CD}$ stretching vibrations of the substituent methyl groups are active in intensity borrowing, and the effects of excitation are delocalized over the entire molecule.     

Crystal field effects in PrAl2

We re-examine the crystal field interpretation of inelastic neutron scattering results on PrAl₂. With the crystal field parameters x = 0.75 and W = 0.315 meV and the molecular field parameter $\text{λ}\text{=}\text{145 kOe}\text{μ}\text{B}$ we can explain the crystal field effects of susceptibility, spontaneous magnetization, specific heat capacity and electrical sensitivity of PrAl₂ rather well.     

Laser excitation spectra of He2

Metastable $\text{a(2sσ)}{}^3\text{Σ}{}_{\mathrm{u}}{}^{\mathrm{+}}$ He₂ molecules are produced by a dc discharge in a flowing He stream. Laser excitation downstream of the discharge produces excitation spectra for a number of He₂ states. LIF spectra are observed for the $\text{(npπ)}{}^3\text{Σ}{}_{\mathrm{g}}{}^{\mathrm{+}}$ series for n = 4–9, excepting 5 and the $\text{(npπ)}{}^3\text{Π}{}_{\mathrm{g}}$ series for n = 5–15.     

Lattice dynamics of the transition metal pentatellurides ZrTe5 and HfTe5

Fresh Raman data collected from the (001) face of a ZrTe₅ single crystal and from polycrystalline powders of ZrTe₅ and HfTe₅ are presented. A simple model assuming only central interactions between nearest neighbour atoms is used for lattice dynamical calculations at $\text{k}\text{=}\text{0}$. The model accounts for the observations and places emphasis on the virtually lacking dynamical coupling between the two basic structural units in these pentatellurides [trigonal-prismatic (MTe₃)_n rods and zig-zag (Te₂)₂ chains].     

Electrical properties of narrow gap semiconductor PtSb2

Results of measurements of conductivity, Hall and Seebeck coefficients of tellurium doped n-type crystals of platinum antimonide are presented. The Hall coefficient and the Seebeck coefficient undergo sign inversion twice, below and above room temperature. The detailed analysis of the experimental results revealed that below 200 K PtSb₂ can be described by a simple conduction and valence band model. The energy gap E_g = (110?0.15 × T) (meV), the electron conductivity mass m_n^c/m₀ = 0.35, acoustic phonon limited electron mobility 〈μ_a〉_n = 3 × 10⁶ T^{?$\text{3}\text{2}$} ($\text{cm}{}^2\text{V · s}$) and mobility ratio 〈μ_a〉_n/〈μ_a〉_p = 0.4 are determined. However, at higher temperatures a more complicated valence band model is needed to account for the experimental results. The arguments for the existence of subsidiary valleys in the valence band are presented.     

EPR lineshape in ethylenediammonium chloromanganate (II), [C2H10N2] [MnCl4]

The EPR line shape has been measured on a single crystal of ethylene diammonium chloromanganate (II) as a function of field orientation with respect to the expected two dimensional network of manganese ions. The angular variation of the linewidth may be described by the expression δH= α + β(3 cos²δ ? 1)² with α = 20 and β = 4, and the lineshape may be described by I(H ? H₀) ? F [exp (? At ? Bt ln ($\text{t}\text{t}{}_0\text{)]}$ (where F refers to the Fourier transform of the bracketed function) with $\text{|}\text{B}\text{A}\text{| = 1.9 ± 0.8}$.     

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.