Magnetic linear dichroism in photoemission from an ultrathin iron silicide film

The effect of magnetic linear dichroism in photoemission of Fe 3p electrons was used to investigate the magnetic properties of the Si(100)2 × 1 surface on which iron films up to 10 monolayers thick were deposited at room temperature under ultrahigh vacuum. The experiments were performed with linearly polarized light (at a photon energy of 135 eV) incident at an angle of 30° to the surface. The photoelectron spectra were measured in a narrow solid angle oriented along the normal to the sample surface for two opposite magnetization directions which were parallel to the surface plane and perpendicular to the polarization vector of the light wave. An analysis of the data obtained showed that the effect has a threshold character and appears after deposition of eight Fe monolayers, when the ferromagnetic silicide Fe₃Si is formed on the surface.     

Investigation of the stability of Mn<Subscript>12</Subscript> single molecule magnets

The stability of single crystals and monolayers of Mn₁₂ single molecule magnets under the influence of X-ray radiation and other possibly disruptive influences has been investigated by means of synchrotron radiation. Clear evidence for radiation induced sample degradation was found for both single crystals and monolayers. The comparison with spectra obtained after damaging the molecules by Ar⁺ sputtering, metal evaporation or water moistening indicates a possibility to distinguish between radiation damage and other external influences. The results clarify some of the previous conflicting reports on the integrity of Mn₁₂ molecules deposited on surfaces and are linked to the investigations aiming at studies of the electronic and magnetic properties of individual Mn₁₂ clusters.     

YCo2: intrinsic magnetic surface of a paramagnetic bulk material

Here we report on results of a spin-resolved photoelectron spectroscopic (SRPES) study of YCo2 thin films (150 A-thick) grown on a W(110) substrate. The films were prepared by co-deposition of stoichiometric amounts of Y and Co onto a clean W surface followed by thermal annealing leading to (2x2) overstructure with respect to W(110) in the low-energy electron diffraction pattern indicated formation of a structurally ordered YCo2(111) surface. While no clear spin asymmetry was observed for bulk-sensitive SRPES data taken at hnu=1253.6 eV, the more surface-sensitive SRPES data obtained at hnu=21.2 eV photon energy revealed a clear spin-asymmetry probing the validity of the recent theoretical prediction.     

Complexation of heterocyclic azo compounds with transition metal ions as found by the laser-induced desorption/ionization method

The Pd, Mn, La, and Rh complexes with the heterocyclic azo compounds were studied by the laser-induced electron transfer desorption/ionization (LETDI) method. The optimum parameters of laser irradiation were found, and the compositions of the complexes were determined. The quantum chemical simulation of the compositions of the complexes was performed on the basis of the data of mass spectrometry. It is shown that laser-induced electron transfer desorption/ionization is an effective tool for the high-sensitive determination and identification of metal complexes.     

Possibility of using an UV–nano-TiO<Subscript>2</Subscript>–K<Subscript>2</Subscript>Cr<Subscript>2</Subscript>O<Subscript>7</Subscript> system for the determination of COD

The results of a study of the optimum oxidation conditions in the system UV?nano-Т?О₂–K₂Cr₂O₇ in a specially designed photoreactor are presented. The basic parameters of the photocatalytic oxidation of glucose and acetic acid were studied and optimized. The oxidation of organic compounds under the optimized conditions was studied. Nano-TiO₂ was shown to be a promising photocatalyst in the design of new oxidation systems for analytical purposes.     

Spin-resolved photoelectron spectroscopy of the MgO/Fe(110) system

The surface structure and electronic properties of ultrathin MgO layers grown on epitaxial Fe(110) films were investigated at room temperature by means of electron diffraction, Auger electron spectroscopy, scanning tunneling microscopy, and spin-resolved photoelectron spectroscopy. The spin polarization at the Fermi level (E_F) of the Fe(110) film decreases sharply with increasing thickness of the MgO layer. This behavior arises from the formation of a thin FeO layer at the MgO(111)/Fe(110) interface, as revealed by structural and spectroscopic investigations. The strong attenuation of the intrinsic spin polarization is qualitatively attributed to the scattering of spin-polarized electrons at the unoccupied d-orbitals of Fe²⁺. PACS 68.35.-p; 68.55.-a; 73.20.r; 75.70.Cn; 79.60.-I     

Quantification of boron in water by of spectrophotometry and thermal lens spectrometry using reaction with beryllon III

The conditions for the thermal lens quantification of boron in aqueous solutions with a detection limit of 0.3 ng/mL are found (λ = 532 nm, laser power 40 mW); this value of the detection limit is an order of magnitude lower than that attainable in conventional spectrophotometry. A 1: 1 composition of an aqueous ethylene glycol mixture is proposed, using which as a medium the detection limit for boron was reduced to 0.1 ng/mL. Using spectrophotometry and thermal lens spectrometry, boron was quantified in mineral water; the results agree with the data acquired by the reference method of inductively coupled plasma atomic emission spectrometry.     

Conservative–dissipative forces and heating mediated by fluctuation electromagnetic field: Two plates in relative nonrelativistic motion

We calculate heating rate, attractive conservative and tangential dissipative fluctuation electromagnetic forces felt by a thick plate moving with nonrelativistic velocity parallel to a closely spaced another plate in rest using relativistic fluctuation electrodynamics. We argue that recently developed relativistic out of equilibrium theory of fluctuation electromagnetic interactions [A.I. Volokitin, B.N.J. Persson, Phys. Rev. B78 (2008) 155437; arXiv:/cond-mat.other/0807.1004v1, 2008] has serious drawbacks.     

Spectrophotometric and thermal lens determination of aluminum with 3-sulfo-5-nitro-4′-diethylamino-2,2′-dihydroxyazobenzene

The conditions of the spectrophotometric and thermal lens determination of aluminum with sulfo-5-nitro-4′-diethylamino-2,2′-dihydroxyazobenzene have been compared. The limit of spectrophotometric detection of aluminum in aqueous solutions has been found to be 8 ng/mL. On the basis of the conditions of spectrophotometric determination, the conditions for thermal lens determination have been proposed (532.0 nm, exciting radiation power of 42 mW); they provide a decrease of the detection limit down to 0.6 ng/mL and an increase of the sensitivity coefficient by an order of magnitude. It has been shown that, in the case of the thermal lens determination of aluminum in water-organic mixtures (50 vol % of dimethyl sulfoxide or 30 vol % acetonitrile), the sensitivity coefficient is respectively 9.1 and 6.3-fold higher as compared with the thermal lens determination in water. As a result, the detection limits are reduced 2.5 and 10-fold, respectively. Aluminum has been determined by thermal lens spectrophotometry in Moscow’s tap water using the standard addition method, its concentration being 0.79 ± 0.07 mg/L, which is above the threshold limit value of the aluminum content of drinking water.