Superfluid-to-normal phase transition and extreme regularity of superdeformed bands

We derive an exact semiclassical expression for the second inertial parameter B for superfluid and normal phases. Interpolation between these limiting values shows that the function B(I) changes sign at the spin I _c that is critical for the rotational spectrum. The quantity B proves to be a sensitive measure of the change in static pairing correlations. The superfluid-to-normal transition reveals itself in a specific variation of the ratio B/A versus the spin I with a plateau characteristic of the normal phase. We find this dependence to be universal for normal deformed and superdeformed bands. A long plateau with a small value of B/A ～ A ^?8/3 explains the extreme regularity of superdeformed bands.     

Magnetic susceptibility of multinary diamondlike semiconductors

Summary The magnetic susceptibility of some A^IB ₂ ^II C^IIIX ₄ ^VI (A^I=Cu, Ag; B^II=Zn, Cd; C^III=Ga, In; X^VI=Se, Te) diamondlike chalcogenides has been measured at RT. Coherently with the form of the relative A^IC^IIIX ₂ ^VI -B^IIX^VI phase diagrams, their magnetic susceptibility fulfils the sum rule typical of ideal solid solutions. Separate values of the diamagnetic and paramagnetic contributions to total magnetic susceptibility are reported and discussed according to a chemical-bond approach previously described. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.     

The theory of infrared dispersion of light in crystals with chalcopyrite lattice

The low-frequency dielectric tensor is calculated for A^IIB^IVC ₂ ^V and A^IB^IIIC ₂ ^VI crystals in terms of the long-wave frequencies of lattice vibrations, corresponding to various orientations of the wave vector. The qualitative shape of the spectrum of mechanical polaritons is obtained. The coefficient of light reflection is calculated as a function of the frequency and direction of propagation for a CdGeP₂ crystal.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 39–43, June, 1978.     

Isospin constraints for two particle distributions in proton proton interactions

From isospin invariance we derive inequalities which relate the (2I _A +1)(2I _B +1) two-particle spectra in the reactionp+p→A+B+ anything, where the measured particles in the final state belong to isospin multipletsI _A ,I _B =0, 1/2, 1.     

High frequency and static dielectric constants of zinc blende structured solids

A correlation is presented for the high frequency ε_∞ and static ε_o dielectric constants of A^IIB^{V I} and A^IIIB^V semiconductors with the zinc blende structure. The high frequency ε_∞ and static ε_o dielectric constants can be represented by an empirical linear relation that is a simple function of melting temperature T_m, atomic volume Ω and product of ionic charges (Z₁Z₂). Values of high frequency ε_∞ and static ε_o dielectric constants of A^IIB^{V I} and A^IIIB^V zinc blende semiconductors exhibit a linear relationship when plotted against the k_BT_m/Ω (k_B=Boltzmann’s constant), but fall on two straight lines according to the product of ionic charges of the compounds. The calculated results are compared with available experimental data and previous calculations based on phenomenological models.     

Two-photon multiterm nonadiabatic transitions

The resonance Raman scattering phenomenon via the predissociated state is described in the four crossing terms A-(1, 2)-B model when terms 1 and 2 strongly interact. The Green's function closed representation for the coupled intermediate electronic terms 1 and 2 is obtained. The transition amplitude I _{A-(1, 2)-B} is found in the WKB approximation. The resonance Raman scattering via the predissociated ³Π_Ou ⁺ state of the interhalogen molecules is treated in detail.     

Hyperfine-structure measurements on Dy161 and Dy163

In an atomic beam magnetic resonance experiment the hyperfine interaction constantsA andB of the⁵ I ₈ groundstate of Dy¹⁶¹ and Dy¹⁶³ were found to be Dy¹⁶¹:A=?(115.8±1)MHz, Dy¹⁶³:A=(162.9±0.6)MHz,B=(1102±15)MHz,B=(1150±20)MHz. Using an effective value for 〈r^?3〉, the magnetic moments and electric quadrupole moments of the Dy¹⁶¹ and Dy¹⁶³ nuclei were calculated to be Dy¹⁶¹:μ _I=?(0.47±0.09) n.m., Dy¹⁶³:μ _I=(0.66±0.13)n.m.,Q=(2.36±0.4)barns,Q=(2.46±0.4)barns.     

Molecular phase separation and cluster size in GeSe2 glass

The local vibrational modes and the microscopic nature of Te sites in GeSe₂-_xTe_x alloy glasses have been examined using Raman and¹²⁹I Mossbauer emission spectroscopy. Two distinct types (A, B) of chalcogen (Te) sites are observed. The Mossbauer site intensities I_B/I_A(x) reveal a power-law variation which on statistical grounds requires that these sites be formed in a cluster. The characteristic size of the cluster is found to be 60–75 A.     

Free states of the canonical anticommutation relations

Each gauge invariant generalized free state _A of the anticommutation relation algebra over a complex Hilbert spaceK is characterized by an operatorA onK. It is shown that the cyclic representations induced by two gauge invariant generalized free states _A and _B are quasi-equivalent if and only if the operatorsA ^1/2–B ^1/2 and (I–A)^1/2–(I–B)^1/2 are of Hilbert-Schmidt class. The combination of this result with results from the theory of isomorphisms of von Neumann algebras yield necessary and sufficient conditions for the unitary equivalence of the cyclic representations induced by gauge invariant generalized free states.Work supported in part by US Atomic Energy Commission, under Contract AT (30-1)-2171 and by the National Science Foundation.     

Spectral properties of chlorines and electron transfer with their participation in the photosynthetic reaction center of photosystem II

Structural factors that provide localization of excited states and determine the properties of primary donor and acceptor of electron in the reaction center of photosystem II (PSII RC) are studied. The results of calculations using stationary and time-dependent density functional theory indicate an important role of protein environments of chlorophylls P_A, P_B, B_A, and B_B and pheophytins H_A and H_B in the area with a radius of no greater than ≤10 Å in the formation of excitonic states of PSII RC. When the neighboring elements are taken into account, the wavelength of long-wavelength Q _y transition of chlorophyll molecules is varied by about 10 nm. The effect is less developed for pheophytin molecules (Δλ ? 2 nm). The following elements strongly affect energy of the transition: His^A198 and His^D197 amino-acid residues that serve as ligands of magnesium atoms affect P_A and P_B, respectively; Met^A183 affects P_A; Met^A172 and Met^D198 affect B_A; water molecules that are located above the planes of the B_A and B_B macrocycles form H bonds with carbonyl groups; and phytol chains of P_A and P_B affect B_A, B_B, H_A, and H_B. The analysis of excitonic states, mutual positions of molecular orbitals of electron donors and acceptors, and matrix elements of electron transfer reaction shows that (i) charge separation between B_A and H_A and P_B and B_A is possible in the active A branch of cofactors of PSII RC and (ii) electron transfer is blocked at the B_B - H_B fragment in inactive B branch of PSII RC.     

Ground state hyperfine structure of95Mo and97Mo

The hyperfine structure of the ground state 4d ⁵ 5s ⁷ S ₃ of⁹⁵Mo and⁹⁷Mo has been measured by the atomic beam magnetic resonance technique with the following results:⁹⁵Mo:A=?208.582060(10)MHz,B=37.050 (100) kHzC=?30 (10) Hz,D=?3 (3) Hz⁹⁷Mo:A=? 212.980930 (10) MHz,B?69.990(140)kHzC=?5 (10) Hz,D=0 (3) Hz. After application of corrections calculated according to second order perturbation theory, the hyperfine structure constants became:⁹⁵Mo: A_c=?208.582560(290)MHz,B _c =16.920(4300)kHzC _c=?30(270) Hz,D _c =? 3 (50) Hz⁹⁷Mo: A_c=212.981450(300) MHz,B _c =?90.780(4400)kHzC _c=?6(270) Hz,D _c =0 (50) Hz. With the known ratio ofg _I(⁹⁵Mo)/g _I(⁹⁷Mo) [1] a calculation of the hyperfine anomaly yields:₉₅ Δ ₉₇=?0.01009(17)%. The ratio of the uncorrectedB factors isB(⁹⁷Mo)/B(⁹⁵Mo)=?1.8890(47). Because of the relatively large effects of second order hyperfine structure, the ratio of the correctedBfactors differs considerably from the ratio of the uncorrectedB factors. From the correctedB factors the electric quadrupole moments may be evaluated by means of calculated radial integrals [2]. The results are:Q (⁹⁵Mo)=?0.019(12)barns,Q(⁹⁷Mo)=0.102(39)barns.     

NMR-ON measurements of123, 124, 131I in nickel

The magnetic hyperfine splitting frequencies of¹²³INi,¹²⁴INi and¹³¹INi in a zero external magnetic field have been determined by the NMR-ON method as 258.9(1), 165.9(1) and 179.5(2) MHz, respectively. With the known values of the magnetic moments, the magnetic hyperfine fields have been deduced:B _HF(¹²³INi)=30.17(5) T,B _HF(¹²⁴INi)=30.14(9) T,B _HF(¹³¹INi)=30.06(4) T; the weighted average isB _HF(INi)=30.11(4) T. The small difference of theB _HF(¹³¹INi) with those of¹²³INi and¹²⁴INi is discussed comparing with results of the hyperfine splitting frequency of iodine in iron host.     

Tetragonal distortion for AIBIIICVI2 chalcopyrite compounds

Pauli-force constants and Simons-Bloch radii for the atoms of groups IB, III and VI are reported. The latter have been used to define a dimensionless quantity ΔX_ch which is found to be correlated in an analytical way with the observed tetragonal distortion δ of A^IB^IIIC^VI₂ type chalcopyrite compounds.     

Systematic behavior ofB(E2) values in the yrast bands of doubly even nuclei

The experimental information onB(E2) transition rates in the yrast bands of doubly even nuclei (126≦A≦184) is systematized. The strength functionS _exp≡B(E2,I→I?2)×E(I→I?2) is found to reveal characteristic behavior significant for structure studies of yrast bands. The energy-weightedB(E2,I→I?2) values (S _exp) and 2?/?²(?: moment of inertia) are plotted versus the rotational frequency squared ?²ω² for each nucleus. In strongly deformed nuclei (N≧90), theS _exp curves smoothly increase for low rotational frequencies suggesting that up to spin valuesI≈8 the ratioQ ₀ ² ? is nearly constant (Q ₀: quadrupole moment). This is not the case in nuclei with a soft core (N≦88). In the relevant discussion, the hydrodynamical model as well as the CAP effect are considered. The results in the backbending region are qualitatively discussed in terms of the two-band crossing model. Evidence is found supporting the prediction of an oscillating behavior of the yrast-yrare interaction.     

Current algebra calculation of e+e-→4π± and determination of ϱ′(1600) parameters

A current algebra calculation of e⁺e^-→4π^± cross section is carried out using the axial current matrix element obtained from τ→π?ν. Assuming ?′→?+2π(I=0, l=0), the following results are obtained: for the A₁ resonance, 1.05?m_A ?1.15 GeV; for ?′, Γ?′(total)≈0.23 GeV, M_?′≈1.5 GeV, Γ(?′→e⁺e^-)≈0.4 keV×B^?1(?′→?′ →?π⁺π).     

The study of the ground state rotational bands in U 233 and U 235 by the inelastic scattering of deuterons

The ground state rotational bands in the odd isotopes of uranium U 233 and U 235, were studied by the inelastic scattering of 13.1 MeV deuterons. Seven members of these bands were seen in both nuclei. By fitting the experimental energies of the levels to the relation E(I)= =AI(I+1)+B[I(I+1)]², the parametersA andB were determined. Their values and the upper limits of the quadrupole reduced transition probabilities determined from the cross sections were: U 233:A=(5.93±0.10)keV,B=(?0.002±0.001)keV,B(E2,5/2→7/2)= =(6.51±0.66)×10^?48 e² cm⁴,B(E2,5/2→9/2)=(2.80±0.37) X 10^?48 e² cm⁴. U 235:A=(5.36±0.04)keV,B=(?0.0017±0.0004) keV,B(E2,7/2→9/2)=(8.05±0.71) × × 10^?48 e² cm⁴,B(E2,7/2→11/2)=(2.17±0.39) X 10^?48 e² cm⁴.     

On kinetic phenomena in semiconducting compounds of AIBIIIC2 VI type with chalcopyrite lattice

A four-ellipsoid model of the vertex of the valence band, proposed earlier for some semiconducting compounds of type A^IB^IIIC₂ ^VI, is examined. The anisotropy of the galvano- and thermomagnetic effects is studied under the assumption of an anisotropic relaxation time and the presence of one scattering mechanism.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 46–51, July, 1973.     

Internal rotation in methyl silane by avoided-crossing molecular-beam spectroscopy

The avoided-crossing molecular-beam electric-resonance technique was applied to methyl silane in the ground torsional state. A new type of anticrossing is introduced which breaks the torsional symmetry and obeys the selection rules ΔJ = 0, K = +1 /a3 ?1. For these “barrier” anticrossings, the values of the crossing fields E_c yield directly the internal rotation splittings; the E_c are independent of the difference (A-B) in the rotational constants. Such anticrossings were observed for J from 1 to 6. Studies were also conducted of several “rotational” anticrossings (J, K) = (1, ±1) /a3 (2, 0) for which E_c does depend on (A-B). The normal rotational transition (J, K) = (1, 0) ← (0, 0) was observed in the ground torsional state using the molecular beam spectrometer. The present data on CH₃²⁸SiH₃ were combined with Hirota's microwave spectra and analyzed with the torsion-rotation Hamiltonian including all quartic centrifugal distortion terms. In addition to evaluating B and several distortion constants, determinations were made of the moment of inertia of the methyl top I_α = 3.165(5) amu-Ų, the effective rotational constant A^eff = 56 189.449(32) MHz, and the effective height of the threefold barrier to internal rotation V₃^eff = 592.3359(73) cm^?1. The correlations leading to these two effective constants are discussed and the true values of A and V₃ are determined within certain approximations. For the isotopic species CH₃³⁰SiH₃, barrier and rotational anticrossings were observed. The isotopic changes in A and V₃ were determined, as well as an upper limit to the corresponding change in I_α.     

Unravelling the visible spectrum of strontium monomethoxide

The bands of the A²E–X²A₁ and B²A₁–X²A₁ electronic transitions of SrO¹²CH₃ and the B²A₁–X²A₁ transition of SrO¹³CH₃ have been recorded at high resolution using a laser ablation jet source. The optical–optical double resonance population depletion technique was used to facilitate the assignment of the spectra. Rotational levels with K = 0, ±1 in the X²A₁ and B²A₁ states and K = 0, 1 and 2 in the A²E state have all been characterised. A perturbation affecting the B²A₁ state caused a reversal of the ordering of the spin-rotation components, F₁ and F₂, in the SrO¹²CH₃ isotopologue. This required the introduction of a modified rotational constant B_mod, affecting only the K = 1, F₂ component of the B²A₁ state, in order to model the SrO¹²CH₃ data in a global fit of the A²E–X²A₁ and B²A₁–X²A₁ transitions.     

Energy band structure and modulation spectra of A2B4C25 semiconductors

The results of the energy band structure calculations of A²B⁴C₂⁵ compounds are reviewed, and the differences in the energy spectra passing from A³B⁵ semiconductors to their closest ternary analogs are described. The origin of the lowest conduction band minima of A²B⁴C₂⁵ compounds was determined from the slopes of the fundamental absorption edge and the pressure coefficients of the energy gap. The investigations of the valence band structure from electroreflectance (ER), thermoreflectance (TR) and wavelength modulated absorption (WMA) spectra are reviewed. In the higher energy region the ER and TR spectra of A²B⁴C₂⁵ compounds were found to be more complicated in comparison with those of their binary analogs. A model of an assignment of the structures in optical spectra of A²B⁴C₂⁵ compounds is discussed.