EPR of V2+ in SrCl2

The X-band EPR spectrum of SrCl₂:V has been measured at liquid nitrogen temperature. A signal associated with V²⁺ in a site of trigonal symmetry is observed. The EPR data have been explained using the spin hamiltonian $\textcolor{red}{}\text{= μ}{}_{\mathrm{\beta }}\text{H}\text{g}\text{?}\text{S}\text{+ D[S}{}^2{}_{\mathrm{z}}\text{?}\text{1}\text{3}\text{S(SH)] +}\text{S}\text{A}\text{?}\text{I}$, with D ? hv, g_∥ = 1.957 ± 0.004, g₆ = 1.954 ± 0.004, A_∥ = 230 ± 5 MHz, A₆ = 235 ± 5 MHz. This V²⁺ defect is similar to those previously reported in fluoride crystals with the fluorite structure.     

Structure,vibrational study and conductivity of the trihydrated uranyl bis(dihydrogenophosphate): UO2(H2PO4)2·3H2O

The X-ray structure (293 K) of UO₂(H₂PO₄)₂·3H₂O has been refined (R = 0.062): M_r = 518g, space group: P2₁/c (Z = 4); $\text{a = 10.816(1)}\text{A}\text{?}$, $\text{b = 13.896(2)}\text{A}\text{?}$, $\text{c = 7.481(1)}\text{A}\text{?}$, β = 105.65(1)^°, $\text{V = 1082.7(2)}\text{A}\text{?}{}^3$; D_c = 3.17 Mg m^?3. The structure consists of infinite chains along the (101) axis with U atoms bridged by two H₂PO₄ groups. The U atom is surrounded by a pentagonal bipyramid of oxygen atoms, one of them being an equatorial water molecule. The cohesion between the chains is ensured by hydrogen bonds involving the two last water molecules. An assignment of IR and Raman bands with isotopic substitution spectra is proposed. A phase transition at 128 K was made evident by DSC and spectroscopy. The room-temperature phase is characterized by a high disorder of the OH bond orientation while in the low-temperature phase H₂O and POH species appear well oriented. The conductivity seems to occur by proton transfer and protonic-species rotation at the POH-water molecular interface between the chains. ac conductivity has been determined by means of the complex-impedance method ($\text{σ}{}_{\mathrm{<mtext>RT</mtext>}}\text{～ (3?12) × 10}{}^{\mathrm{?5}}\text{Ω}{}^{\mathrm{?1}}\text{cm}{}^{\mathrm{?1}}$; E ～ 0.20 eV).     

Infrared bands of 12C2HD

The rotational structure of about 40 bands of ¹²C₂HD observed in the region 6000?600 cm^?1 has been measured and interpreted with the purpose of determining a comprehensive set of molecular constants for this isotopic variety of acetylene. Combining these data with the results for ¹²C₂H₂ and ¹²C₂D₂, a reevaluation of the equilibrium internuclear distances for the acetylene molecule has been made: $\text{r}{}_{\mathrm{e}}\text{(CH) = 1.06215 ± 17 × 10}{}^{\mathrm{?5}}\text{A}\text{?}$ and $\text{r}{}_{\mathrm{e}}\text{(CC) = 1.20257 ± 9 × 10}{}^{\mathrm{?5}}\text{A}\text{?}$ were obtained. This paper presents all the molecular constants derived in this study.     

KL0-KS0 transmission regeneration on hydrogen

The energy dependence of the modulus and phase of the K_L⁰-K_S⁰ regeneration amplitude on hydrogen in the range of 14–50 GeV has been investigated at the Serpukhov 70 GeV accelerator.It has been established that the modulus of the modified regeneration amplitude decreases with increasing momentum as $\text{2|?}{}_{21}{}^0\text{(p)|/k = (0.84 ± 0.42) · p}{}^{\mathrm{?0.50\pm 0.15}}\text{mb}$. The amplitude phase is energy-independent and its mean value is ?₂₁⁰ = ?132° ± 5°. The results obtained are compared with other experiments and with predictions of different theoretical models.     

Polarization spectroscopy of the E0g+-B0u+ band system of Br2

The E-B (0_g⁺-0_u⁺) band system of Br₂ has been investigated at Doppler-limited resolution using polarization labeling spectroscopy. Merged E state data for the three naturally occurring isotopes in the range v_E = 0–16, expressed in terms of the constants for ⁷⁹Br₂, are (in cm^?1) Y_0,0 = 49 777.962(54), Y_1,0 = 150.834(22), Y_2,0 = ?0.4182(28), Y_3,0 = 6.6(11) × 10^?4, Y_0,1 = 4.1876(28) × 10^?2, Y_1,1 = ?1.607(16) × 10^?4, and Y_0,2 = 1.39(39) × 10^?8. The bond distance is $\text{r}{}_{\mathrm{<mtext>e</mtext>}}\text{= 3.194}\text{A}\text{?}$, and the diabatic dissociation energy to $\text{Br}{}^{\mathrm{+}}\text{(}{}^3\text{P}{}_2\text{) +}\text{Br}{}^{\mathrm{?}}\text{(}{}^1\text{S}{}_0\text{)}\text{is 34 700 cm}{}^{\mathrm{?1}}$.     

Lifetimes of the low-lying 72− states in 113, 115Cd

The half-lives of the $\text{7}\text{2}{}^{\mathrm{?}}$ states at 522.6 and 393.9 keV in ¹¹³Cd and ¹¹⁵Cd have been determined to be 0.322±0.012 and 0.75± 0.03 ns, respectively. Values of the $\text{B(}\text{E}\text{2,}\text{7}\text{2}{}^{\mathrm{?}}\text{→}\text{11}\text{2}{}^{\mathrm{?}}$) and the energy difference in odd Cd (A = 113–119) are compared with those in neighbouring even Cd. The level properties are interpreted in the framework of the triaxial rotor model.     

Measurement of the 2S12−2P12 splitting in the (μ−4He)+ muonic ion

The measurement of the $\text{2S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→ 2P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ energy transition in muonic helium is presented. The energy difference S¹ is found to be S_exp¹ = 1381.3±0.5 meV. This result agrees with the expected value $\text{S}\text{?}{}^1\text{= 1381.2±0.3}\text{meV}$ obtained assuming the previously measured value for the $\text{2S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→ 2P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ energy difference.     

The electronic isotope shift in the A2Π-X2Σ+ bands of BeH,BeD and BeT

The 0-0, 1-1, 2-2, and 3-3 bands of the A²Π-X²Σ⁺ transition of the tritiated beryllium monohydride molecule have been observed at 5000 Å in emission using a beryllium hollow-cathode discharge in a He + T₂ mixture. The rotational analysis of these bands yields the following principal molecular constants.

$\text{A}{}^2\text{Π:}\text{B}{}_{\mathrm{e}}\text{= 4.192}\text{cm}{}^{\mathrm{?1}}\text{; r}{}_{\mathrm{e}}\text{= 1.333}\text{A}\text{?}$

$\text{X}{}^2\text{Σ:}\text{B}{}_{\mathrm{e}}\text{= 4.142}\text{cm}{}^{\mathrm{?1}}\text{; r}{}_{\mathrm{e}}\text{= 1.341}\text{A}\text{?}$

$\text{ω}{}_{\mathrm{e}}\text{′ ? ω}{}_{\mathrm{e}}\text{″ = 16.36}\text{cm}{}^{\mathrm{?1}}\text{; ω}{}_{\mathrm{e}}\text{′X}{}_{\mathrm{e}}\text{′ ? ω}{}_{\mathrm{e}}\text{″X}{}_{\mathrm{e}}\text{″ = 0.84}\text{cm}{}^{\mathrm{?1}}$

From the pure electronic energy difference (E_Π - E_Σ)_BeT = 20 037.91 ± 1.5 cm^?1 and the corresponding previously known values for BeH and BeD, the following electronic isotope shifts are derived

$\text{ΔE}{}_{\mathrm{e}}{}^{\mathrm{i}}\text{(}\text{BeH}\text{?}\text{BeT}\text{) = ?4.7 ≠ 1.5}\text{cm}{}^1\text{, ΔE}{}_{\mathrm{e}}{}^{\mathrm{i}}\text{(}\text{BeH}\text{?}\text{BeT}\text{) = ?1.8 ≠ 1.5}\text{cm}{}^1$

and related to the theoretical approach given by Bunker to the problem of the breakdown of the Born-Oppenheimer approximation.     

The dipole moment of thioformaldehyde in its singlet and triplet π1 − n excited states

Laser-induced fluorescence excitation has been used to measure Stark splittings of selected lines in the $\text{A}\text{?}{}^1\text{A}{}_2\text{-}\text{X}\text{?}{}^1\text{A}{}_1$ and $\text{a}\text{?}{}^3\text{A}{}_2\text{-}\text{X}\text{?}{}^1\text{A}{}_2$ band systems of H₂CS in electric fields up to 13 kV/cm. The derived excited state a-axis dipole moments are 0.820 ± 0.007 D for the 4¹ level of the ¹A₂ state; 0.838 ± 0.008 D for the zeroth vibrational level of ¹A₂; and 0.534 ± 0.015 D for the zeroth vibrational level of the ³A₂ state. These results are compared with the corresponding values of H₂CO, and interpreted in terms of the changing localization of the π and $\text{π}{}^1$ orbitals accompanying electronic excitation.     

Electron paramagnetic resonance of 61Ni+ in CuGaS2

EPR of ⁶¹Ni⁺ doped CuGaS₂ at 4.2 K leads to the following experimental data: $\text{g = 1.918 ± 0.006 A  < 12 × 10}{}^{-4}\text{cm}{}^{-1}\text{, g}{}_{\mathrm{\perp }}\text{= 2.328±0.006 A}{}_{\mathrm{\perp }}\text{= (65±2) × 10}{}^{-4}\text{cm}{}^{-1}$. High axial field splitting of ²T₂ state stabilizes the center against Jahn-Teller interaction. Covalency reduction factor k is 0.76.     

Chemical diffusion in nonstoichiometric chromium sulfide,Cr2+yS3

Using the re-equilibration kinetic method the chemical diffusion coefficient in nonstoichiometric chromium sesquisulfide, Cr_2+yS₃, has been determined as a function of temperature (1073–1373 K) and sulphur vapour pressure (10?10⁴ Pa). It has been found that this coefficient is independent of sulphur pressure and can be described by the following empirical equation: $\text{D}\text{?}\text{Cr}{}_{\mathrm{2+y}}\text{S}{}_3\text{=50.86}\text{exp(-39070 cal/mole/}\text{RT)}\text{(cm}{}^2\text{s}{}^{\mathrm{?1)}}$. It has been shown that the mobility of the point defects inCr_2+yS₃ is independent of their concentration and that the self-diffusion coefficient of chromium in this sulfide has the following function of temperature and sulphur pressure: . (cm²s^?1).     

Electron paramagnetic resonance of Gd3 in YCl3·6H2O

The electron paramagnetic resonance spectrum of Gd³⁺ in YCl₃·6H₂0 with $\text{1}\text{100}$ dilution of Gd/Y ions, has been studied with an X-band spectrometer at 295, 77 and 1.77°K and with a K-band spectrometer at 295 and 77°K. The individual values of all the parameters are evaluated from the data at the three temperatures. In particular, the following values for the g-tensor and the zero-field splitting parameters b₂⁰ and b₂² are obtained from X-band data: at 295°K, g_zz = 1.994±0.005, g_xx = 1.992±0.005, g_yy = 1.997±0.005, b₂⁰ = 1.898 ±0.015 GHz, b₂² = ?2.247 ± 0.015GHz; at 77°K, g_zz = 1.999±0.008, g_xx = 2.000±0.008, b₂⁰= 1.978 ±0.022 GHz, b₂² = ?1.574±0.022GHz; at 1.77°K, g_zz = 2.002±0.010, g_xx = 1.990 ±0.010, b₂⁰ = 2.011 ± 0.025 GHz, b₂² = ?1.650 ±0.025 GHz. (The K-band values are found to be consistent with the X-band values). From the angular dependence of the data in the ZX plane (i) the angle X₀ which the Z axis makes with the a vector of the unit cell, is determined to be 58.00 ±0.25° and (ii) the existence of pseudo-symmetry axes at ±5° from the Z axis in the ZX plane as found by heat capacity and specific heat data has been confirmed. An estimate is also made of the extent of admixture of the excited ${}^6\text{P}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ state with the ground state ${}^8\text{S}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$.     

Measurement and interpretation of the 1-0 band of 14N16O at 1900 cm−1

The wavenumbers of the vibration rotation band lines of ¹⁴N¹⁶O are reported for the ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{-}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{-}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and ${}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{-}{}^2\text{Π}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ subbands of the 1-0 transition in the infrared. The full set of spectroscopic constants for this band has been determined by direct approach using the analysis of Zare, Schmeltekopf, Harrop, and Albritton. In addition to the band origin ν₀ and the B, D, H constants for the lower and upper vibrational levels, the following spin-orbit coupling constants have been derived: $\text{A}\text{?}{}_0\text{= 123.02772 ± 0.00011}$ and $\text{A}\text{?}{}_1\text{= 122.78248 ± 0.00011}$ (in cm^?1). Apparent centrifugal corrections to these constants have been determined and the values obtained for them are $\text{A}\text{?}{}_{\mathrm{<mtext>D</mtext><mtext>0</mtext>}}\text{= (0.347573 ± 0.00051) × 10}{}^{\mathrm{?3}}$ and $\text{A}\text{?}{}_{\mathrm{<mtext>D</mtext><mtext>1</mtext>}}\text{= (0.337135 ± 0.00050) × 10}{}^{\mathrm{?3}}\text{cm}{}^{\mathrm{?1}}$. Λ-Type doubling constants evaluated by using both grating and tunable laser data are also reported.     

Static moments of the first excited states of 32, 34S and 204, 206Pb

The reorientation effect in Coulomb excitation has been used to measure the following static quadrupole moments: $\text{Q}{}_2\text{+ (}{}^{32}\text{S}\text{) = ?0.066 ± 0.017}\text{b}\text{, Q}{}_2\text{+ (}{}^{34}\text{S}\text{) = 0.026 ± 0.023}\text{b}\text{, Q}{}_2\text{+ (}{}^{204}\text{Pb}\text{) = 0.19 ± 0.14}\text{b}$. Interference effects from higher excited states have been included in the analysis, with the signs of the E2 matrix elements taken from an anharmonic model. The value obtained for $\text{Q}{}_2\text{+ (}{}^{32}\text{S}\text{)}$ is in disagreement with two previous measurements. We attribute the discrepancy to the smaller internucleon separation distances involved in the previous experiments, which can cause deviations from Coulomb excitation cross sections. The other quadrupole moments have not been measured previously. The B (E2: 0⁺ → 2⁺) measured were: $\text{0.0305 ± 0.0016 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{32}\text{S}\text{), 0.025 ± 0.004 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{34}\text{S}\text{),}\text{and}\text{0.166 ± 0.009 e}{}^2\text{·}\text{b}{}^2\text{(}{}^{204}\text{Pb}\text{)}$. From the angular distribution of the de-excitation γ-rays of the Pb nuclei following recoil into vacuum, we have determined the following $\text{g-}\text{factors}\text{: ¦g}{}_2\text{+ (}{}^{204}\text{Pb}\text{)¦ < 0.08}$ (two standard deviations), $\text{¦g}{}_2\text{+ (}{}^{206}\text{Pb}\text{)¦ = 0.07}{}^{\mathrm{+\; 0.07}}{}_{\mathrm{?\; 0.03}}$. Our value of $\text{g}{}_2\text{+ (}{}^{206}\text{Pb}\text{)}$ is in agreement with a previous measurement.     

Charge density wave commensurability in 2H-TaS2 and AgxTaS2

The charge density wave transition in 2H-TaS₂near 75 K has been observed to be incommensurate, using electron diffraction, with $\text{q}{}^1\text{= (}\text{0.338}\text{±}\text{0.002}\text{)a}{}^1{}_0$ along the 〈10.0〉 directions which, within the experimental uncertainty, remains temperature independent to about 14 K. Incommensurate charge density formation is also observed in Ag_xTaS₂ samples for $\text{x?}\text{0.26}$ with an increase in q¹ to $\text{(}\text{0.347}\text{±}\text{0.002}\text{)a}{}^1{}_0$ when x?0.26. Within the experimental error q¹ appears to be temperature independent to 25 K.     

Transverse spin correlation function of the one-dimensional spin-12 XY model

The transverse spin pair correlation function p^x_n=<S^x_mS^x_m+n>=<S^x_mS^x_m+n> is calculated exactly in the thermodynamic limit of the system described by the one-dimensional, isotropic, spin-$\text{1}\text{2}$, XY Hamiltonian

$\text{H=?2J}\text{∑}\text{l=1}\text{N}\text{(S}{}^{\mathrm{x}}{}_{\mathrm{l}}\text{S}{}^{\mathrm{x}}{}_{\mathrm{l+1}}\text{+S}{}^{\mathrm{y}}{}_{\mathrm{l}}\text{S}{}^{\mathrm{y}}{}_{\mathrm{l+1}}\text{)}$

. It is found that at absolute zero temperature (T = 0), the correlation function ρ^x_n for n ≥ 0 is given by

$\text{ρ}{}^{\mathrm{x}}{}_{\mathrm{2p}}\text{=}\text{1}\text{4}\text{2}\text{π}{}^{\mathrm{2p}}\text{Π}\text{j=1}\text{p?1}\text{4j}{}^2\text{4j}{}^2\text{?1}{}^{\mathrm{2p?2j}}\text{if}\text{n=2p}$

,

$\text{ρ}{}^{\mathrm{x}}{}_{\mathrm{2p+1}}\text{=±}\text{1}\text{4}\text{2}\text{π}{}^{\mathrm{2p+1}}\text{Π}\text{j=1}\text{p}\text{4j}{}^2\text{4j}{}^2\text{?1}{}^{\mathrm{2p+2j}}\text{if}\text{n=2p+1}$

, where the plus sign applies when J is positive and the minus sign applies when J is negative. From these the asymptotic behavior as n → ∞ of |?^x_n| at T = 0 is derived to be $\text{|ρ}{}^{\mathrm{x}}{}_{\mathrm{n}}\text{| ～}\text{a}\text{n}$ with a = 0.147088?. For finite temperatures, ρ^x_n is calculated numerically. By using the results for ?^x_n, the transverse inverse correlation length and the wavenumber dependent transverse spin pair correlation function are also calculated exactly.     

Magnetic moments of Jπ = 192− mirror states in 43Ti and 43Sc

The time-differential perturbed angular distribution method was used to determine the g-factors of the $\text{(}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{)}{}^3\text{19}\text{2}{}^{\mathrm{?}}$ states in ⁴³Ti and ⁴³Sc. The results for the mass 43 mirror pair are: ${}^{43}\text{Ti}\text{: g = 0.760 ± 0.001, T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{, = 560 ± 6}\text{ns}$, ${}^{43}\text{Sc}\text{: g = 0.3286± 0.0007, T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 473 ± 5}\text{ns}$. Considering in addition the magnetic moments in A = 41 and 42, it is suggested that the deformed states considered by Johnstone and Castel and by Erikson are responsible for the observed large deviations from the Schmidt values.     

Heat capacity and thermodynamic properties of α-Fe2O3 in the region 300–1050 K. antiferromagnetic transition

The heat capacity of synthetic α-Fe₂O₃ has been measured in the range 300–1050K by adiabatic shield calorimetry with intermittent energy inputs and temperature equilibration in between. A λ-type transition, related to the change from antiferro- to paramagnetism in the compound, is delineated and a maximum heat capacity of about 195 JK^?1 mole^?1 is observed over a 3 K interval around 955 K. Values of thermodynamic functions have been derived and C_P (1000K), [H⁰(1000K)-H⁰(0)], and [S⁰(1000K)-S⁰(0)] are 149.0JK^?1 mole^?1, 115.72 kJ mole^?1, and 252.27 JK^?1 mole^?1, respectively, after inclusion of earlier low-temperature results [X⁰ (298.15K)-X⁰(0)]. The non-magnetic heat capacity is estimated and the thermodynamic properties of the magnetic transition evaluated. The results are compared with spin-wave calculations in the random phase approximation below the Néel temperature and the Oguchi pair model above. An upper estimate of the total magnetic entropy gives 32.4JK^?1 mole^?1, which compares favorably with that calculated for randomization of five unpaired electron spins on each iron, ΔS = 2R ln 6 = 29.79 JK^?1 mole^?1 for α-Fe₂O₃. The critical exponent α in the equation $\text{C}{}_{\mathrm{m}}\text{= (}\text{A}\text{α}\text{) [(|T}{}_{\mathrm{<mtext>n</mtext>}}\text{?T|/T}{}_{\mathrm{<mtext>n</mtext>}}\text{)?1]}{}^{\mathrm{?\alpha }}\text{+ B}$ is ?(0.50±0.10) below the maximum and 0.15±0.10 above, for T_n = 955.0K. The high temperature tail is discussed in terms of short range order.     

Lifetime of electronic states of CO2+

The radiative lifetimes of the $\text{A}\text{?}{}^2\text{Π}{}_{\mathrm{u}}$ and $\text{B}\text{?}{}^2\text{Σ}{}_{\mathrm{u}}{}^{\mathrm{+}}$ states of CO₂⁺ were measured by means of the delayed coincidence method. Excitation was performed by a pulsed electron beam incident on CO₂. The results of these measurements are 115 ± 5 nsec for the $\text{A}\text{?}{}^2\text{Π}{}_{\mathrm{u}}$ state and 126 ± 3 nsec for the $\text{B}\text{?}{}^2\text{Σ}{}_{\mathrm{u}}{}^{\mathrm{+}}$ state.     

The ππ and KK amplitudes,the S1 and the quark structure of 0++ resonances

The nature of mesons in the 0⁺⁺ nonet is studied. In particular we discuss the parameterization of the I = 0 S wave in terms of the S¹ and possible ? mesons. The S¹ parameters are determined by fitting to π^?π⁺ and K^?K⁺ production data. In particular we find .