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International audience; A β-decay experiment aiming at investigation of the low-spin structure of 100Zr was performed using the GRIFFIN spectrometer at TRIUMFISAC. Based on the obtained data, a new 2 + state is postulated which is degenerate in energy with the established (5+) level at 2209 keV.

Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new high-efficiency γ -ray spectrometer designed for use in decay spectroscopy experiments with low-energy radioactive ion beams provided by TRIUMF’s Isotope Separator and Accelerator (ISAC-I) facility. GRIFFIN is composed of sixteen Compton-suppressed large-volume clover-type high-purity germanium (HPGe) γ -ray detectors combined with a suite of ancillary detection systems and coupled to a custom digital data acquisition system. The infrastructure and detectors of the spectrometer as well as the performance characteristics and the analysis techniques applied to the experimental data are described.

The $\beta$-decay of neutron-rich $^{129}$In into $^{129}$Sn was studied using the GRIFFIN spectrometer at the ISAC facility at TRIUMF. The study observed the half-lives of the ground state and each of the $\beta$-decaying isomers. The level scheme of $^{129}$Sn has been expanded with thirty-one new $\gamma$-ray transitions and nine new excited levels, leading to a re-evaluation of the $\beta$-branching ratios and level spin assignments. The observation of the $\beta$-decay of the (29/2$^{+}$) 1911-keV isomeric state in $^{129}$In is reported for the first time, with a branching ratio of 2.0(5)$\%$.

The Ge80 structure was investigated in a high-statistics β-decay experiment of Ga80 using the GRIFFIN spectrometer at TRIUMF-ISAC through γ, β-e, e-γ, and γ-γ spectroscopy. No evidence was found for the recently reported 02+ 639-keV level suggested as evidence for low-energy shape coexistence in Ge80. Large-scale shell model calculations performed in Ge78,80,82 place the 02+ level in Ge80 at 2 MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in Ge80.

Spectroscopy of doubly magic $^{132}_{50}$Sn$_{82}$ has been performed with the GRIFFIN spectrometer at TRIUMF-ISAC following the $\beta$ decay of $^{132}_{49}$In$_{83}$. The analysis has allowed for the placement of a total of 70 transitions and 29 excited states in $^{132}$Sn. Detailed spectroscopy has also been performed on $^{131}$Sb, resulting from the $\beta$ decay of $^{131}$Sn, produced from the $\beta$-delayed neutron decay of $^{132}$In. Measurement of $\gamma$-rays in both $^{131}$Sn and $^{131}$Sb has led to the determination of the $\beta$-delayed neutron emission probability, $P_{n}$, from $^{132}$In. This is the first time the $P_{n}$ has been measured for this nucleus using $\gamma$ spectroscopy, and the new value of 12.3(4)% is consistent with the most recent $\beta-n$ counting experiment. Additionally, $\gamma$-$\gamma$ angular correlations have been performed in $^{132}$Sn, supporting the spin assignments of several excited states. Novel ab initio calculations are presented which describe several of the excited states, and these are compared to the experimental spectrum.

Three nearly degenerate pairs of doublet bands are identified in $^{131}$Ba. Two of them, with positive-parity, are interpreted as pseudospin-chiral quartet bands. This is the first time that a complete set of chiral doublet bands built on the pseudospin partners π(d5/2,g7/2) is observed. The chiral bands with opposite parity built on 3-quasiparticle configurations are directly connected by many E1 transitions, without involving an intermediary non-chiral configuration. The observed band structures in $^{131}$Ba have been investigated by using the reflection-asymmetric particle rotor model. The energies and the electromagnetic transition ratios of the three pairs of doublet bands observed in $^{131}$Ba are reproduced and they are interpreted as chiral doublet bands with three-quasiparticle configurations. It is the first time that multiple chiral bands are observed in the presence of enhanced octupole correlations and pseudospin symmetry.

The half-lives of three β-decaying states of 13149In82 have been measured with the GRIFFIN γ-ray spectrometer at the TRIUMF-ISAC facility to be T1/2(1/2−)=328(15)ms, T1/2(9/2+)=265(8)ms, and T1/2(21/2+)=323(55)ms, respectively. The first observation of γ rays following the βn decay of 131In into 130Sn is reported. The β-delayed neutron emission probability is determined to be P1n=12(7)% for the 21/2+ state and 2.3(3)% from the combined 1/2− and 9/2+ states of 13149In82 observed in this experiment. A significant expansion of the decay scheme of 131In, including 17 new excited states and 35 new γ-ray transitions in 13150Sn81 is also reported. This leads to large changes in the deduced β-branching ratios to some of the low-lying states of 131Sn compared to previous work with implications for the strength of the first-forbidden β transitions in the vicinity of doubly magic 13250Sn82. (Less)

The band built on the Kπ = 8−, T1/2 = 9.4 ms isomer of 130Ba has been identified, filling the gap in the systematics of the dipole bands built on the 8− isomers in the N = 74 isotones from 128Xe to 138Gd. The use of the GALILEO array in conjunction with its ancillaries EUCLIDES and Neutron Wall, helped to firmly place the newly identified transitions on top of the long-lived isomer. The extracted gK and gR gyromagnetic factors are in agreement with the 7/2+[404] ⊗ 9/2−[514] two-neutron Nilsson configuration. Particle-rotor model calculations give an understanding of the limited degree of K mixing. The experimental information on the Kπ = 8− isomer of 130Ba is now the most complete among the K isomers of the N = 74 isotones.

Several new bands have been identified in 130Ba, among which there is one with band-head spin 8+. Its properties are in agreement with the Fermi-aligned \nu h11/2^2 , 7/2+[523] \otimes 9/2-[514] Nilsson configuration. This is the first observation of a two-quasiparticle t-band in the A=130 mass region. The t-band is fed by a dipole band involving two additional h11/2 protons. The odd-spin partners of the proton and neutron S-bands and the ground-state band at high spins are also newly identified. The observed bands are discussed using several theoretical models, which strongly suggest the coexistence of prolate and oblate shapes polarized by rotation aligned two-proton and two-neutron configurations, as well as prolate collective rotations around axes with different orientations. With the new results, 130Ba presents one of the best and most complete sets of collective excitations that a gamma-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the A = 130 mass region., Comment: 8 pages, 7 figures

Ablative fractional laser (AFL) increases uptake of topically applied skin agents. The coagulation zone (CZ) surrounding vertically ablated channels may influence uptake of drugs.To investigate impact of CZ thickness on skin fluorescence intensities (FI) of a hydrophilic molecule by means of fluorescence microscopy (FM) and fluorescence confocal microscopy (FCM). Second, to compare FI of hydrophilic and lipophilic test molecules by FCM.Microchannels with CZ thicknesses of 0, 20, and 80 µm were generated by microneedles or AFL (10,600 nm). Channels were 700 µm deep and number of channels kept constant per skin area. After 4 hours of incubation, FI induced by sodium fluorescein (NAF, hydrophilic, logarithmic partition-coefficient (logP) = -1.52, MW = 376.26) were quantified in both CZ and surrounding skin by FM (0-1,500 µm) and FCM (0-90 µm). FI of NAF and carboxyfluorescein (CAF, lipophilic, logP = 2.9, MW = 376.32) were compared by FCM.By FM, NAF-induced FI were higher in CZ than in surrounding skin (P ≤ 0.001). Highest NAF-FI were induced in skin pretreated with a thin CZ (CZ-20 µm), assessed by both FM and FCM and in particular, FI were higher than in skin pretreated with no CZ (CZ-0 µm) (FM P ≤ 0.041, FCM P 0.012). Skin FI remained constant to a depth of 500 µm, which corresponded to approximate depth of microchannels (CZ-0 µm, CZ-20 µm, CZ-80 µm: 0-500 µm P ≥ 0.107). In accordance with FM data, FCM showed higher FI within CZ than in surrounding skin, but gradually decreased to zero at a depth of 90 µm. NAF-FI were higher than CAF-FI (P ≤ 0.036), and highest CAF-FI were induced by CZ-0 µm and CZ-20 µm compared to CZ-80 µm (P ≤ 0.009).The influence of the CZ thickness on skin FI differs between small hydrophilic and lipophilic test molecules. Results may have clinical relevance for laser-assisted drug delivery. Lasers Surg. Med. 51:68-78, 2019. © 2018 Wiley Periodicals, Inc.

Background. Healthcare systems in industrialised countries are challenged to provide care for a growing number of older adults. Information technology holds the promise of facilitating this process by providing support for care staff, and improving wellbeing of older adults through a variety of support systems. Goal. Little is known about the challenges that arise from the deployment of technology in care settings; yet, the integration of technology into care is one of the core determinants of successful support. In this paper, we discuss challenges and opportunities associated with technology integration in care using the example of a mobile robot to support physical therapy among older adults with cognitive impairment in the European project STRANDS. Results and discussion. We report on technical challenges along with perspectives of physical therapists, and provide an overview of lessons learned which we hope will help inform the work of researchers and practitioners wishing to integrate robotic aids in the caregiving process.

High rate film deposition via Gas Flow Sputtering was used to develop both metallic titanium films and ceramic titania coatings for implants. The structure formation of the coatings can be described by a modified model of structure zones according to Thornton. The potential of Gas Flow Sputtering for designing implant surfaces with controlled morphology and roughness is demonstrated.

The β-decay half lives of nuclei near the r-process path are critical information required for abundance calculations, especially those near neutron number N = 82. Specifically, the nuclei below doubly-magic 132Sn are key, and play an important role in the formation and shape of the second r-process abundance peak. The half lives in this region are challenging to measure due to the significant β-delayed neutron decay branches and the population of isomeric states with half lives comparable to the ground states. However, by measuring the time distribution of γ rays, these complications can be eliminated. This requires, however, a very effcient γ-ray spectrometer since the production of isotopes in this region is very limited. The new GRIFFIN array at TRIUMF-ISAC provides the high effciency required for these measurements. Recent improvements in the quality of the beams produced at TRIUMF, employing the IG-LIS device, are outlined, as well as the current status of the ARIEL facility. The GRIFFIN spectrometer and its use are briefly described. The experiment to measure the half lives of 128-130Cd is outlined and the results given, and some examples of the power of GRIFFIN to expand decay schemes, specifically for the decay of 128Cd to 128In, are given.

With the Strip Hollow Cathode (SHC) process a new plasma-assisted chemical vapor deposition (PACVD) process was introduced, which was shown to meet the requirements of dynamic steel strip coating with plasma polymer films from several monomers, utilizing the hollow cathode effect. The operating pressure is in the upper fine vacuum range; the SHC process therefore does not require an extensive vacuum environment. Now, this process has been applied to the deposition of silicon oxide, titanium oxide and amorphous carbon films. The films were deposited onto steel and other conducting sheet substrates, even on coil coated steel strip with a polymer film thickness of at least 50 μm. All films show a dense, pinhole-free structure and are highly uniform in film thickness. The hardness of amorphous carbon and silicon oxide polymer films exhibited values of 19 and 3 GPa, respectively, which is well suited for many scratch protection applications. Additionally, measurements of dielectric breakdown strength yield values higher than 10 MV/cm for both 300 nm and 600 nm thick silicon oxide films. Ellipsometric measurements yield a refraction index of 1.47 (550 nm) in the case of silicon oxide. Color and tribological properties such as hardness, Young's modulus, and scratch resistivity have been evaluated.

The MBE growth of type III HgTe/Hg 1− x Cd x Te heterostructures will be discussed. Spin–orbit (s–o) coupling is particularily large in HgTe based quantum wells; the observed value of 17 meV is at least two to three times larger than values reported in the literature for III–V heterostructures or any other system. Rashba spin–orbit splitting in n type modulation doped quantum wells (QWs) has been investigated as a function of the 2DEG density and compared with self-consistent Hartree calculations based on an 8×8 k · p model. Furthermore the presence of two periodic SdH oscillations in p type QWs with an inverted band structure has been observed and is the first direct evidence that these heterostructures are indirect semiconductors.

Sol–gel indium tin oxide films (ITO) of different thickness (120±25−40 to 560±25−40 nm) and of various compositions (In:Sn=90:10, 70:30 and 50:50) prepared from In metal and Sn salt were deposited on silica-coated (∼200 nm thickness) sheet glass substrate by the spinning technique. The films were cured in reducing atmosphere (N2+H2O vapour) at 500±5 °C, and these were of bixbyite-type structure with cubic In2O3 phase. Directional hemispherical reflectance (Rh) and transmittance (Th) of the films were measured in the wavelength range 0.25–18 μm. The Rh in the IR region was found to be maximum (∼0.62 at 10 μm) for In:Sn=70:30 resulting in minimum thermal emissivity (ed=0.36). The thermal emissivity (ed) was evaluated from the relation, ed=1−Rh−Th (Th≈0 for sheet glass in the wavelength range 5–18 μm), and it was in the range 0.36–0.85. The achieved sheet resistance of the films was in the range 55–1700 Ω/□. Resistivity of the films of relatively low sheet resistance measured by van der Pauw method at ambient temperature was in the range (1.4±0.2)×10−3 to (3.5±0.6)×10−3 Ω cm, and it was minimum for In:Sn=70:30 which resulted in maximum carrier concentration. Free electron carrier concentration (N) and Hall mobility (μ) of the films were in the range (1.4±0.4)×1020 to (4.8±1.3)×1020 cm−3 and (9.5±2.4) to (13±3) cm2/V s, respectively. The Hall mobility of the films passes through minima with an increase in tin content.

We present evidence of the influence of the substrate (GaAs and CdZnTe) on the magnetic properties and on the surface structure of (001) zinc-blende MnTe grown by molecular beam epitaxy. High-resolution X-ray diffraction and atomic force microscopy were employed in the characterisation of the MnTe structure. The temperature dependence of collective spin excitations (magnons) was determined via Raman scattering and subsequently analysed in order to study selected magnetic properties. Differences in both the Neel temperature and magneto-elastic coupling between the MnTe layer and the given substrate were demonstrated, and mechanisms contributing to these effects are discussed. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The band structure of HgTe quantum wells (QWs) has been determined from absorption experiments on superlattices in conjunction with calculations based on an 8×8 k · p model. The band structure combined with self-consistent Hartree calculations has enabled transport results to be quantitatively explained. Rashba spin–orbit, (SO) splitting has been investigated in n-type modulation doped HgTe QWs by means of Shubnikov–de Haas oscillations (SdH) in gated Hall bars. The heavy hole nature of the H1 conduction subband in QWs with an inverted band structure greatly enhances the Rashba SO splitting, with values up to 17 meV . By analyzing the SdH oscillations of a magnetic two-dimensional electron gas (2DEG) in modulation-doped n-type Hg 1− x Mn x Te QWs, we have been able to separate the gate voltage-dependent Rashba SO splitting from the temperature-dependent giant Zeeman splitting, which are of comparable magnitudes. In addition, hot electrons and Mn ions in a magnetic 2DEG have been investigated as a function of current. Nano-scale structures of lower dimensions are planned and experiments on sub-micrometer magneto-transport structures have resulted in the first evidence for ballistic transport in quasi-1D HgTe QW structures.

The effective g-factor of modulation doped n-type HgTe single quantum wells, SQWs, has been determined by the coincidence method in tilted magnetic fields to lie between 15 and 35. For symmetrically doped samples the effective g-factor has been found to be constant for different filling factors; however, for asymmetric SQWs, a large increase with increasing filling factor has been observed. This can be ascribed to a combination of Zeeman spin splitting and Rashba spin–orbit splitting. Reasonable agreement has been achieved between theoretical calculations based on the 8×8 k · p method and experimental results.

Sol–gel indium tin oxide films (ITO) of various composition (In:Sn atomic ratio=90:10 to 30:70) prepared from salt-based precursors were deposited on bare and SiO2 coated (∼200 nm thickness) sheet glass substrates. The films were cured in air and then annealed under N2/H2O at ∼500 °C to obtain ITO films of thickness 250–320 nm. Directional hemispherical reflectance (Rh) and trasmittance (Th) of the films were measured in the wavelength range 0.25–18 μm. The reflectance of the films at 10 μm (near the peak wavelength of black body radiation) was in the range 0.18–0.55. The thermal emissivity (ed) was evaluated from the relation: ed=1−Rh−Th (Th≈0, for sheet glass in the wavelength range 5–18 μm) and it was in the range 0.47–0.90. Reflectance (Rh) was also evaluated from measured sheet resistance values (R□), from the relation Rh=(1+2e0c0R□)−2, where e0 and c0 are the permittivity of electron in vacuum and velocity of light, respectively. Specific resistivity of the films, measured by van-der Pauw method at ambient temperature was in the range 1.7±0.3×10−3 to 6.6±1.2×10−3 Ω cm. The sheet resistance (R□) of the films was in the range 68–212 Ω/□. Free electron carrier concentration (N) and Hall mobility (μ) of the films were in the ranges (0.66±0.18)×1020 to (3.7±1.0)×1020 cm−3 and (4.4±1.5) to (20±5) cm2/V s, respectively. These values were utilized to evaluate plasma wavelength (λP) of the conducting films which were in the range 1.72±0.24–4.07±0.58 μm. Considerable variations of the above properties were observed with increasing Sn content but minimum thermal emissivity and maximum IR reflectivity were observed in the case of In:Sn=70:30.

We employ spin-quantum-beat spectroscopy to investigate the carrier-density dependence of the spin-precession frequency and the magnitude of the Faraday rotation of Cd1−x Mn x Te samples at fixed magnetic field. We find an onset of saturation of the Faraday rotation at carrier densities as low as 4× 1016 cm−3 and attribute it to electrons (not holes which dominate in other types of experiments). The spin splitting at fixed magnetic field remains density dependent down to 3 × 1015 cm−3 (the lowest density accessible in our measurements) which suggests a direct influence of the carrier-density on the sp–d exchange not mediated by screening effects.

A large Rashba spin splitting has been observed in the first conduction subband of n-type modulation doped HgTe quantum wells with an inverted band structure via an investigation of Shubnikov–de Haas oscillations as a function of gate voltage. Self-consistent Hartree calculations of the band structure based on an 8 × 8 k ⋅ p model quantitatively describe the experimental results. It has been shown that the heavy-hole nature of the H1 conduction subband greatly influences the spatial distribution of electrons in the quantum well and also enhances the Rashba spin splitting at large electron densities. These are unique features of type III heterostructures in the inverted band regime. The βk3∥ dispersion predicted by an analytical model is a good approximation of the self-consistent Hartree calculations for small values of the in-plane wave vector k∥. This is in contrast to the commonly used αk∥ dispersion for the conduction subband in type I heterojunctions.

The MBE growth of Hg 1− x Cd x Te alloys and type III HgTe/Hg 1− x Cd x Te heterostructures has been discussed, including similarities and differences between the (0 0 1) and (1 1 2)B orientations. Furthermore the MBE growth of HgTe based quantum wells (QWs) with the incorporation of Mn are additional topics. An investigation of the optical properties of type III superlattices with a normal band structure has lead to information about band structure of these heterostructures as well as information about the interface and the semimetallic QW. For example, by means of the full 8×8 Kane Hamiltonian in the envelope function approximation, it has been demonstrated that the energy separation between the H1–E1 and L1–E1 intersubband transition energies is primarily determined by the valence band offset, Λ, between HgTe and CdTe. This has led to unambiguous values for the offset and its temperature dependence, i.e. Λ( T )=570±60 meV and dΛ/d T =−0.40±0.04T meV/K. Furthermore the energy gap of HgTe at room temperature has also been determined. Magneto-transport measurements of n-type QWs show very pronounced Shubnikov-de Haas (SdH) oscillations and well developed quantum Hall plateaus for temperatures up to approximately 60 K. A large Rashba spin–orbit splitting of the first conduction subband, H1, has been observed in HgTe/Hg 1− x Cd x Te QWs with an inverted band structure. Self-consistent Hartree calculations of the band structure based on the above model allows us to quantitatively describe the experimental results and demonstrates that the heavy hole nature of the H1 subband greatly influences the spatial distribution of electrons in the QW and thus enhances the Rashba spin splitting, i.e. Δ E H1 = βk ∥ 3 . Furthermore, the presence of two periodic SdH oscillations in p-type QWs with an inverted band structure has been observed and is the first direct evidence that these heterostructures are indirect semiconductors. The influence of Mn in the upper barrier on the 2D electrons in the well has been investigated as a function of their separation. With spacer thicknesses of 10 and 15 nm, no appreciable change is observed, however, a reduction of the spacer thickness to 5 nm results in an increase in the maximum population difference between the two Rashba spin split H1 subbands by a factor of approximately two.

A series of gate controlled n-type asymmetrically modulation doped HgTe quantum wells (QWs) with Mn in one of the barriers have been investigated. From a Fourier analysis of the Shubnikovde Haas (SdH) oscillations, the population difference of the two spin split H1 subbands has been determined for three QWs with different spacer thicknesses between the quantum well and the Mn ions. This population difference shows a significant enhancement in the QW with a 5 nm spacer compared to the QWs with 10 and 15 nm thick spacers. The latter results agree with the predictions for Rashba spin-orbit splitting, however, we must assume that Mn in the QW with the thin spacer increases the asymmetry of the QW.

Femtosecond transmission spectra of highly polar CdTe are compared to more covalent GaAs contrasting semiclassical kinetics with two-time quantum kinetics based on the Dyson equation. Nonequilibrium heavy holes in CdTe show ultrafast energy redistribution via the Fröhlich mechanism even if photoexcited below the LO phonon energy. This subthreshold relaxation is a genuine quantum kinetic effect. It gains importance if the polaron self-energy is comparable to the phonon energy. Conservation of the free-particle energies is not required under these conditions.

The surface termination and geometric structure of molecular beam epitaxially (MBE)-grown HgSe(001) has been studied by means of X-ray photoelectron spectroscopy (XPS) and high-resolution low-energy electron diffraction. The surface exhibit a c (2×2) reconstruction and is terminated by Hg. In addition, the valence band offset of the HgSe/CdSe(001) heterostructure has been investigated by k -resolved ultraviolet photoemission (UPS). Special care was taken to determine the true position of the VB maximum in the Brillouin zone ( Γ -point) by using Ar–I excitation during the angle-dependent UPS measurements. Thus, the valence band discontinuity was determined as 0.58±0.05 eV. This value and recent results for the HgTe/CdTe heterojunction support the trend expected by theory predicting a larger Δ E VBO for selenides than for tellurides.

Stimulated by recent photoemission results which suggest a positive fundamental energy gap in HgSe, we have investigated the electronic structure of molecular beam epitaxially grown HgSe(001) $c(2\ifmmode\times\else\texttimes\fi{}2)$ layers by a combination of direct ultraviolet photoemission spectroscopy (UPS) and inverse (IPES) photoelectron spectroscopy. Our UPS results do not support the finding of additional peaks above the valence band maximum (VBM) of Gawlik et al. [Phys. Rev. Lett. 78, 3165 (1997)]. A comparison of angle-integrated UPS and IPES spectra and ab initio calculated density of states of HgSe and HgTe demonstrates dissimilar behavior of the two compounds in the dispersion of the conduction bands between 0 and 2 eV above the VBM. Our results are compatible with the common view that HgSe is a semimetal.

Nondegenerate four-wave-mixing allows one to monitor the femtosecond relaxation of free carriers in GaAs and CdTe at densities as low as $2\ifmmode\times\else\texttimes\fi{}{10}^{15}$ ${\mathrm{cm}}^{\ensuremath{-}3}.$ The energy relaxation time of electrons via LO-phonon emission is determined to be $240\ifmmode\pm\else\textpm\fi{}20$ fs in GaAs. In more polar CdTe, this time constant is found to be as short as $70\ifmmode\pm\else\textpm\fi{}15$ fs which is even shorter than the phonon oscillation period of 200 fs.

The application of Multichannel Silicone Rubber Traps for the direct analysis of organic compounds in water was studied. The optimum collection flow rate for a 10 mL sample was found to be ca. 150 μL·min–1. The effect of methanol on the retention power of the trap was evaluated. The addition of a methanol fraction of up to 40% to the water standards did not show any loss in collection efficiency. It was shown that the extraction of organic compounds from water with the multichannel trap is uncomplicated, i. e. methanol is not required to achieve accurate analyses, concentration of the sample onto the trap is by gravity flow, and excess water remaining in the multichannel trap after water extraction is removed by centrifugation. With the use of the multichannel silicone rubber trap a wide boiling point range of compounds were analyzed from aqueous samples at levels of 1–4 μg·L–1.

We have investigated the valence band offset (ΔE VBO ) of the molecular beam epitaxially grown heterostructure HgTe/CdTe(001) by k-resolved ultraviolet (UPS) and X-ray (XPS) photoemission. Our angle-dependent UPS measurements at two different photon energies demonstrate that the dispersion of the valence band (VB) must be checked carefully in order to find the true position of the VB maximum in the Brillouin zone. With this information the valence band discontinuity was determined as (0.53 ± 0.03) eV, which is different from previously found photoemission values but now agrees well with magneto-optical investigations. In addition, we have determined the energy gap of CdTe(001) and HgTe(001) by a combination of UV and inverse photoemission. The energy gap of CdTe is determined to (1.57 ± 0.06) eV and that for HgTe as (0.0 ± 0.06) eV. We therefore conclude that HgTe is a semi-metal with inverted band structure in agreement with other results.

Die paramagnetischen Rhenium(II)-Nitrosylkomplexe [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)], [Re(NO) · Cl2(OPPh3)2(OReO3)] und [Re(NO)Cl2(OPPh3)3](ReO4) entstehen bei der Reaktion von [ReOCl3(PPh3)2] mit NO-Gas in CH2Cl2/EtOH. Im Verlauf der Reaktion konnen diese und zwei weitere ReII-Komplexe mit 5 d5 „low-spin”-Konfiguration EPR-spektroskopisch und massenspektrometrisch nachgewiesen werden. Die Kristallstrukturanalyse weist fur die isolierten Nitrosylkomplexe linear koordinierte NO-Liganden (Re–N–O-Winkel zwischen 171,9 und 177,3°) aus. Im Endprodukt der Reaktion, [Re(NO)Cl2(OPPh3)3][ReO4] (monoklin, P21/c, a = 13,47(1), b = 17,56(1), c = 24,69(2) A, β = 95,12(4)°, Z = 4), sind drei OPPh3-Liganden meridional koordiniert. Die Zwischenprodukte [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)] (triklin, P 1, a = 10,561(6), b = 11,770(4), c = 18,483(8) A, α = 77,29(3), β = 73,53(3), γ = 64,70(4)°, Z = 2) und [Re(NO)Cl2(OPPh3)2(OReO3)] (monoklin P21/c, a = 10,652(1), b = 31,638(4), c = 11,886(1) A, β = 115,59(1)°, Z = 4) konnen neben [Re(NO)Cl3(Ph3P)2], [Re(NO) · Cl3(Ph3P)(Ph3PO)] und [ReCl4(Ph3P)2] bei kurzeren Reaktionszeiten isoliert werden. Synthesis, Structures, and EPR-Spectra of the Rhenium(II) Nitrosyl Complexes [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)], [Re(NO)Cl2(OPPh3)2(OReO3)], and [Re(NO)Cl2(OPPh3)3](ReO4) The paramagnetic rhenium(II) nitrosyl complexes [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)], [Re(NO)Cl2(OPPh3)2 · (OReO3)], and [Re(NO)Cl2(OPPh3)3](ReO4) are formed during the reaction of [ReOCl3(PPh3)2] with NO gas in CH2Cl2/EtOH. These and two other ReII complexes with 5 d5 ”low-spin””-configuration can be observed during the reaction EPR spectroscopically. Crystal structure analysis shows linear coordinated NO ligands (Re–N–O-angles between 171.9 and 177.3°). Three OPPh3 ligands are meridionally coordinated in the final product of the reaction, [Re(NO)Cl2(OPPh3)3][ReO4] (monoclinic, P21/c, a = 13.47(1), b = 17.56(1), c = 24.69(2) A, β = 95.12(4)°, Z = 4). [Re(NO)Cl2(PPh3)(OPPh3)(OReO3)] (triclinic P 1, a = 10.561(6), b = 11.770(4), c = 18.483(8) A, α = 77.29(3), β = 73.53(3), γ = 64.70(4)°, Z = 2) and [Re(NO)Cl2 (OPPh3)2(OReO3)] (monoclinic P21/c, a = 10.652(1), b = 31.638(4), c = 11.886(1) A, β = 115.59(1)°), Z = 4) can be isolated at shorter reaction times besides the complexes [Re(NO)Cl3(Ph3P)2], [Re(NO)Cl3(Ph3P) · (Ph3PO)], and [ReCl4(Ph3P)2].

The molecular beam epitaxial growth and the optical properties of (1 1 2)B oriented HgTe/Hg 1-x Cd x Te superlattices (SLs) are compared with those of (0 0 1) orientated SLs. First of all, the Hg 1-x Cd x Te barriers have a much higher Cd concentration than those in (0 0 1) grown under similar conditions, i.e. x = 0.95 ± 0.02 as opposed to x = 0.68 ± 0.02 at a growth temperature of 180 C. In addition the optical absorption edges are appreciably sharper than those in (0 0 1) oriented SLs grown under similar conditions, by a factor of at least two. Analogously, the full-width at half-maximum of the photoluminescence (PL) peaky e.g. 8 meV for a band gap of 100 meV at 4 K. is at least a factor of two narrower than that in our best (0 0 1) oriented SLs. This can be explained by a more homogeneous growth laterally, i.e. in the plane perpendicular to the growth direction: either more homogeneous quantum well and barrier thicknesses or a more homogeneous interface width.

Dichloro-2-(N,N-dimethylaminomethyl)-phenylgold(III), [Au(damp-C,N)Cl2], hergestellt durch Umsetzung von [Hg(damp)Cl] mit Na[AuCl4], kristallisiert monoklin, Raumgruppe P21/c mit a = 7,896(3); b = 9,487(2); c = 15,107(6) A; β = 100,22(3)°, Z = 4. Die Kristallstruktur besteht aus monomeren [Au(damp-CN)Cl2]-Einheiten mit quadratisch-planar koordinierten Goldatomen. Die kleinsten Gold-Gold-Abstande betragen 4,977 A. [Au(damp-C,N)(OOCCH3)2] wird durch Reaktion von [Au(damp-C,N)Cl2] mit AgOOCCH3 in CH2Cl2 hergestellt und aus feuchtem CH2C12 als [Au(damp-C,N)(OOCCH3)2] · 0,5 H2O kristallisiert: monoklin, Raumgruppe C2/c a = 16,626(8); b = 10,640(1); c = 16,271(7) A; β = 91,90(2)°, Z = 8. Das Goldatom ist quadratisch-planar koordiniert. Die Acetatoliganden binden jeweils einzahnig. Das in das Kristallgitter eingebaute Losungsmittel ist durch Wasserstoffbrucken in die Festkorperstruktur eingebunden. Die Chloroliganden von [Au(damp-C,N)Cl2] konnen leicht durch zweifach negativ geladene Chelatliganden ausgetauscht werden. Die Reaktion mit Na2mnt in Aceton er gibt in nahczu quantitativer Ausbeute den Neutralkomplex [Au(damp-C,N)(mnt)], der in der orthorhombischen Raumgruppe Pna21 kristallisiert (a = 7,651(1); b = 14,476(1); c = 13,353(1) A, Z = 4). Das Goldatom befindet sich in einer quadratisch-planaren Koordinationsumgebung. Die Au-S-Abstande betragen 2,363(2) bzw. 2,270(2) A. Gold(III) Complexes with 2-(N,N-dimethylaminomethyl)phenyl (damp−). Syntheses and Structures of [Au(damp-C,N)Cl2], [Au(damp-C,N)(OOCCH3)2] and [Au(damp-C,N)(mnt)] (mnt2− = 1.2-dicyanoethene-1.2-dithiolate) Dichloro-2-(N,N-dimethylaminomethyl)phenylgold(III), [Au(damp-C,N)Cl2], was prepared by the reaction of [Hg(damp)Cl] with Na[AuCl4] and crystallizes monoclinic, space group P21/c a = 7.896(3), b = 9.487(2), c = 15.107(6) A, β = 100.22(3)°, Z = 4. The crystal structure consists of monomeric [Au(damp-C,N)Cl2] units with square-planar coordinated gold atoms. The shortest Au-Au distances are 4.977 A. [Au(damp-C,N)(OOCCH3)2] can be synthesized by the reaction of [Au(damp-C,N)Cl2] and AgOOCCH3 in CH2Cl2. Single crystals of the composition [Au(damp-C,N)(OOCCH3)2]. 0.5 H2O were obtained from moist CH2Cl2: monoclinic, space group C2/c, a = 16.626(8), b = 10.640(1), c = 16.271(7) A, β = 91.90(2)°, Z = 8. The gold atom is square-planar coordinated. The acetato ligands are bound monodentately. The solvent water forms strong hydrogen bridges to the complex molecules in the solid state structure. The chloro ligands in [Au(damp-C,N)Cl2] can easily be replaced by dianionic chelate ligands. The reaction with Na2mnt (mnt2− = 1.2-dicyanoethene-l.2-dithiolate) gives in almost quantitative yield the neutral complex [Au(damp-C,N)(mnt)], which crystallizes orthorhombic, space group Pna21 with a = 7.651(1), b = 14.476(1), c = 13.353(1 ) A, Z = 4. The gold atom is square-planar coordinated. The Au-S distances are 2.363(2) A and 2.270(2) A, respectively.

Established standard methods for analyzing semi-volatile pollutants by capillary gas chromatography are cumbersome, time-consuming, and expensive. With the longer term aim of replacing the sample preparation procedures with convenient concertrating and thermal desorption steps, thick film silicone rubber traps were constructed in a novel multi-channel configuration. Tests were performed to determine breakthrough volumes and thermal desorption characteristics for total transfer of the trap contents to a capillary column. Initial results are very promising.

p-type HgTe/Hg0.3Cd0.7Te(001) quantum wells (QWs) have been grown with molecular-beam epitaxy (MBE) on Cd0.96Zn0.04Te substrates using modulation doping techniques. Both plasma-excited nitrogen and evaporated cadmium arsenide have been utilized for in situ doping during MBE growth. A comparison of the electrical and structural properties of QWs fabricated by the two doping techniques has been made. Two-dimensional hole concentrations in nitrogen-doped QWs (up to 1.0×1012 cm−2) were significantly higher than in arsenic-doped QWs (below 0.5×1012 cm−2). However, by means of a gate-controlled Hall bar, hole densities up to 1.1×1012 cm−2 have been achieved in the latter system. Hall mobilities up to 1.0×105 cm2/(V s) have been measured. Whereas all samples exhibit pronounced although irregular Shubnikov–de Haas oscillations, quantum Hall plateaus in the arsenic-doped samples are broader and better defined.

We have observed a characteristic modulation in the amplitude of the Shubnikov–de Haas (SdH) oscillations and a large shift of node position with increasing temperature in the semimagnetic semiconductor Hg1−xMnxTe. The positions of the oscillation extrema are almost temperature independent, with the exception that their phase changes by π after passing the nodal point. These features can be explained in terms of the exchange interaction between conduction electrons and the localized spin moments of Mn ions. The antiferromagnetic temperature and effective spin have been deduced from the temperature-dependent node position in the SdH oscillations.

Detectors in the far infrared based on HgTe/Hg1-xCdxTe superlattices (SL's) are superior to those based on Hg1-xCdxTe alloys. This is based on their band structure, however, it was concluded in an investigation of the hydrostatic pressure dependence of photoluminescence (PL) peaks investigation reported in Phys. Rev. B 48, 4460 (1993) that either the band structure model was incorrect or the observed PL peaks were related to impurities. In contrast, in optical absorption experiments, the hydrostatic pressure dependence of intersubband transitions agrees with theory, which corroborates the validity of the band structure model. The first advantage is the required precision of the growth parameters for the desired band gap or cut off wavelength (λco). More important is the possibility to significantly reduce leak currents by the appropriate choice of barrier thickness. Furthermore the absorption edge is much steeper and therefore the SL can be much thinner. Due to Auger suppression in these type III SL's, carrier lifetimes are significantly enhanced. Finally the SL is significantly less susceptible to a Burstein-Moss shift of the adsorption edge; at least an order of magnitude greater electron concentration is necessary in order to produce the same Burstein-Moss shift. A method for in situ p type doped quantum wells (QW's) and SL's with nitrogen and arsenic by means of molecular beam epitaxy (MBE) is discussed.

With the implementation of recombinant DNA technology in the pharmaceutical industry, some synthetic insulins have been developed in order to improve the therapy of diabetes. These analogues differ only slightly in the amino acid sequence, therefore displaying a great challenge for analytical chemistry. Within the work presented in this paper, capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC) with sodium dodecylsulphate (SDS) as micelle-forming agent, and microemulsion electrokinetic chromatography (MEEKC) with microemulsions consisting of SDS, n-octane and 1-butanol were investigated for the separation of human insulin and five synthetic analogues. Best results were achieved with a solvent-modified MEKC system consisting of 100 mM sodium dodecyl sulphate and 15% acetonitrile in 10 mM borate buffer (pH 9.2). A similar system based on perfluorooctanoic acid as micelle-forming agent in ammonium acetate (pH 9.2) was successfully employed for the hyphenation with a quadrupole/time-of-flight mass spectrometer via a sheath-flow interface. In this case, detection limits at 10 mg/L could be achieved.

The effective g factor of modulation doped n-type HgTe single quantum wells, SQW's, has been determined by the coincidence method in tilted magnetic fields to lie between 15 and 35. For symmetrically doped samples the effective g factor has been found to be constant for different filling factors; however, for asymmetric SQW's, a large increase with increasing filling factor has been observed. This can be ascribed to a combination of Zeeman spin splitting and Rashba spin-orbit splitting. Reasonable agreement has been achieved between theoretical calculations based on the $8\ifmmode\times\else\texttimes\fi{}8\mathit{k}\ensuremath{\cdot}\mathit{p}$ method and experimental results.

Properties of the valence-band structure of modulation-doped type-III $\mathrm{HgTe}/{\mathrm{Hg}}_{1\ensuremath{-}x}{\mathrm{Cd}}_{x}\mathrm{Te}(001)$ quantum wells (QW's) have been studied by means of magneto-transport experiments and self-consistent Hartree calculations using the full $8\ifmmode\times\else\texttimes\fi{}8\mathit{k}\ensuremath{\cdot}\mathit{p}$ Hamiltonian in the envelope-function approximation. A metallic top gate was used in order to investigate the band structure by varying the hole concentration or the Fermi energy. This resulted in direct experimental evidence of an indirect band gap in a quantum well with an inverted band structure. The Kramers degeneracy for finite k is removed, and only one spin-orbit split valence subband is occupied due to the indirect band structure. The fourfold symmetry of the $H2$ valence band at finite values of ${\mathit{k}}_{\ensuremath{\Vert}}$ is also reflected in a QW with a normal band structure, whose $H1$ valence band has four occupied secondary maxima at finite values of ${\mathit{k}}_{\ensuremath{\Vert}}$ in addition to the central maximum.

Magneto-intersubband scattering (MIS), which is a general feature in III-V semiconductor heterostructures with two occupied subbands, is demonstrated to be absent in both asymmetric and symmetric type-III HgTe quantum wells (QW's). The analysis of the temperature dependence of Shubnikov--de Haas (SdH) oscillations and their fast Fourier transforms, together with the excellent agreement between the measured longitudinal resistivity and the calculated oscillations in the density of states in a magnetic field within the framework of an $8\ifmmode\times\else\texttimes\fi{}8$ $\mathbf{k}\ensuremath{\cdot}\mathbf{p}$ model, completely rule out the MIS effect. The absence of the MIS effect in HgTe QW's is ascribed to a much more complex and irregular Landau level alignment which suppresses the intersubband scattering rate. A natural consequence of the absence of MIS is that the Rashba spin splitting can be properly identified from the SdH oscillations in a perpendicular magnetic field and at a constant temperature, in contrast to the recent findings for InAs QW's.

Ultrashort bursts of silicon $K\ensuremath{\alpha}$ x-ray radiation from femtosecond-laser-produced plasmas have been generated. A cross-correlation measurement employing a laser-triggered ultrafast structural change of a CdTe crystal layer (320 nm) shows a $K\ensuremath{\alpha}$ pulse duration between 200 fs and 640 fs. This result is corroborated by particle in cell simulations combined with a Monte-Carlo electron stopping code and calculations on the structural changes of the crystal lattice.

Ultrashort bursts of silicon K alpha x-ray radiation from femtosecond-laser-produced plasmas have been generated. A cross-correlation measurement employing a laser-triggered ultrafast structural change of a CdTe crystal layer (320 nm) shows a K alpha pulse duration between 200 fs and 640 fs. This result is corroborated by particle in cell simulations combined with a Monte-Carlo electron stopping code and calculations on the structural changes of the crystal lattice.