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The electro-optical Kerr effect induced by a slowly varying electric field in liquid helium at temperatures below the lambda point is investigated. The Kerr constant of liquid helium is measured to be (1.43+/-0.02(stat)+/-0.04(sys)) x 10(-20) (cm/V)(2) at T=1.5 K. Within experimental uncertainty, the Kerr constant is independent of temperature in the range T=1.5 K to 2.17 K, which implies that the Kerr constant of the superfluid component of liquid helium is the same as that of normal liquid helium. Pair and higher correlations of He atoms in the liquid phase account for about 23% of the measured Kerr constant. Liquid nitrogen was used to test the experimental setup; the result for the liquid nitrogen Kerr constant is (4.38+/-0.15) x 10(-18) (cm/V)(2). Kerr effect can be used as a noncontact technique for measuring the magnitude and mapping out the distribution of electric fields inside these cryogenic insulants. 相似文献
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Streptomyces omiyaensis SSM 5670 was characterized by its ability to use compression moulded samples of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as its sole carbon source. Biodegradation of PHBV in liquid mineral salts medium was investigated using scanning electron microscopy, gravimetric measurements, capillary viscometry, tensile testing and wide angle X-ray spectroscopy. The biodegradation of PHBV proceeds via surface erosion mechanism, resulting in the formation of pits by microbial attack. PHBV specimens lost about 45% of their original weight after 45 days of exposure. During the degradation process the elastic modulus reduces less than 10%. The formation of pores and microcracks initiated at the degraded pits determines the reduction of the elongation and stress at break. However, the true stress at break is practically independent of the degradation time. No significant changes of PHBV molecular weight or crystallinity were observed during biodegradation. The polymer chain cleavage occurred only at the specimen surface and does not discriminate between crystalline and amorphous states. 相似文献
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Voronov DL Anderson EH Gullikson EM Salmassi F Warwick T Yashchuk VV Padmore HA 《Optics letters》2012,37(10):1628-1630
Diffraction efficiency of multilayer-coated blazed gratings (MBG) strongly depends on the perfection of the sawtooth-shaped layers in the overall composite structure. Growth of multilayers on sawtooth substrates should be carefully optimized to reduce groove profile distortion and, at the same time, to avoid significant roughening of multilayer interfaces. In this work, we report on a way to optimize growth of sputter-deposited Mo/Si multilayers on sawtooth substrates through variation of the sputtering gas pressure. We believe a new record for diffraction efficiency of 44% was achieved for an optimized MBG with groove density of 5250 lines/mm at the wavelength of 13.1 nm. 相似文献
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M. U. Belyi A. S. Kolesnik B. A. Okhrimenko V. P. Yashchuk 《Journal of Applied Spectroscopy》1989,50(5):523-529
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 50, No. 5, pp. 808–814, May, 1989. 相似文献
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Troitskii B. B. Domrachev G. A. Semchikov Yu. D. Khokhlova L. V. Anikina L. I. Denisova V. N. Novikova M. A. Marsenova Yu. A. Yashchuk L. M. 《Russian Journal of General Chemistry》2002,72(8):1276-1281
Fullerene-C60 inhibits thermal and thermooxidative degradation of copolymers of methyl methacrylate with styrene, butyl acrylate, glycidyl methacrylate, and hydroxyethyl methacrylate. 相似文献
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Seltzer SJ Michalak DJ Donaldson MH Balabas MV Barber SK Bernasek SL Bouchiat MA Hexemer A Hibberd AM Kimball DF Jaye C Karaulanov T Narducci FA Rangwala SA Robinson HG Shmakov AK Voronov DL Yashchuk VV Pines A Budker D 《The Journal of chemical physics》2010,133(14):144703
Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10?000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C[Double Bond]C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials. 相似文献
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T Y Ogulchansky M Y Losytskyy V B Kovalska S S Lukashov V M Yashchuk S M Yarmoluk 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2001,57(13):2705-2715
Spectral properties of carbocyanine dye 3-methyl-2-[3-methyl-2-(3-methyl-2,3-dihydro-1,3-benzothiazole-2-iliden)-1- butenyl]-1,3-benzothiazole-3-il iodide (Cyan betaiPr) in water solution, as well as in the presence of different types of double stranded DNA have been studied. While in water solution of 'free' dye Cyan betaiPr stays mainly in monomeric form, in the presence of DNA the dye molecules form J-aggregates. The molecular structure of these J-aggregates causes the Davydov splitting of their absorption band, corresponding to the first electronic transition. A study of site-specificity showed that in the presence of poly (dA/dT) the majority of Cyan betaiPr molecules form J-aggregates, while in the presence of poly (dGC/dGC) dye molecules stay mainly in monomeric form and in presence of chicken erythrocytes DNA both J-aggregate and monomeric forms of dye are present. We suppose that Cyan betaiPr molecules aggregate in DNA groove, which serves as a template for J-aggregate forming. An increase of ionic strength of solution leads to the release of dye molecules from DNA grooves and prevents J-aggregates formation. 相似文献
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Nonlinear magneto-optical rotation is investigated at high light powers where the rotation is significantly modified by ac Stark shifts. These shifts are shown to change the overall sign of rotation for closed F-->F+1 transitions compared to the low light power limit. The effect is demonstrated by measurements in rubidium and density matrix calculations. The results are important for applications of nonlinear optical rotation such as sensitive magnetometry. 相似文献