Nm For Cr Research Articles

Red sensitivity of dichromated cellulose triacetate as a holographic recording material

The red sensitivity of dichromated cellulose triacetate holographic recording material without any dye sensitization is reported. We suggest that the sensitivity is due to the absorption at 590 nm of the intermediate Cr(V) formed in the reducing process of chromium from Cr(VI) to Cr(III). In the experiment, the real-time transmission gratings are recorded with 632.8-nm irradiation from a He-Ne laser.

Crystal-field analysis of Cr3+ in grossular Ca3Al2(SiO4)3

Abstract The optical absorption and luminescence spectra of Cr 3+ in Ca 3 Al 2 (SiO 4 ) 3 natural garnet (Grossular) measured at room and LHeT were reported the first time in Mazurak [Opt. Mater., this issue]. The spectra have been used for determined energies of R 2 , R 1 , ZPL, vibrational modes and 2 E, 4 T 2 , 4 T 1 levels. We have extended our investigations, the spectra of Cr 3+ in Ca 3 Al 2 (SiO 4 ) 3 are analyzed using a C 3i crystal-field Hamiltonian. The energy levels and the crystal-field parameters B nm for Cr 3+ ion in Ca 3 Al 2 (SiO 4 ) 3 single crystal, including spin-orbit and ligand-field interactions, have been calculated. The resulting crystal-field parameters B nm represent very well the crystal-field interactions of Cr 3+ in Grossular Ca 3 Al 2 (SiO 4 ) 3 .

Seagoing method for the determination of chromium(III) and total chromium in sea water by electron-capture detection gas chromatography

A seagoing method for the determination of Cr(III) and total chromium in sea water is presented. The method employs electron-capture detection of the volatile trifluoroacetylacetone derivative of Cr(III) formed via solvent extraction with toluene; total chromium is determined as Cr(III) after reduction. Detection limits at sea are 0.062 and 0.255 nM for Cr(III) and total chromium, respectively. Accuracy for total chromium was verified by the analysis of standard reference materials from the National Research Council of Canada. The procedure has a precision of 1.3% at 4.7 nM total chromium, and has been applied to stored samples in the laboratory in addition to its use at sea.

Investigation of the laser properties of Cr/sup 3+/:LiSrGaF/sub 6/

A boule of Cr:LiSGAF (Cr/sup 3+/:LiSrGaF/sub 6/), the Ga analog of Cr:LiSAF, was grown, a laser sample was fabricated, and its efficiency was measured using a laser-pumped laser configuration. The laser performance near 820 nm and related properties of Cr:LiSGAF are reported. The use of Sr instead of Ca results in a red shift of the absorption and emission band (along with an increase in the emission cross section). Insight into the effect of a change in the identity of the substitutional site on the properties of the laser is provided. >

Luminescence during Eu, Fe and Cr implantation into CaF 2

A study has been made of luminescence from single crystal CaF 2 during ion-implantation with Eu. Fe, or Cr ions of 100 keV as a function of the implantation dose. It was found that the color of luminescence during ion-implantation into CaF 2 depended on the ion species and ion dose. The spectra for Eu-implanted specimens have four peaks at ~ 360, ~ 430, ~ 600 and ~ 690 nm. The spectra with Fe and Cr have three peaks at ~ 360, ~ 500 and ~ 650 nm, and the peak at ~ 500 nm for Fe and at ~ 360 nm for Cr is highest. These optical properties of implanted CaF 2 depended on aging time in atmosphere at room temperature after ion implantation. Channeling measurements were employed to determine the radiation damage and lattice sites of implanted elements. The change in color of luminescence is discussed with respect to the radiation damage.

Infrared spectroscopic study of Cr and Cu metallization of polyimide

Infrared spectra of polyimide films [pyromellitic dianhydride–oxydianiline (PMDA–ODA)]metallized with 1 nm of Cr or Cu are used to describe the nature of metal–polyimide bonds formed at the interface. Cr and Cu cause similar changes in the polyimide spectrum though larger changes were observed for the more reactive Cr. The spectral evidence indicates that the metals react predominantly with the PMDA part of the polyimide with only minor interactions with the ODA segment. The results confirm previous observations which suggest that the carbonyl groups on the polymer surface are the primary reaction sites; no complex formation between the metal atoms and the aromatic rings in the polymer chain was observed. These conclusions are supported by infrared studies of Cr or Cu metallized poly(ethylene terephthalate) thin films.

Intermetallic formation with indium solder

This study investigates metallurgical interactions between indium solder and thin film metal layers. Intermetallic formation is an important reliability concern with solder joints because the compounds are typically brittle phases that act as stress concentrators during thermal and power cycling of a device [1], Experiments were carried out for the thin film structure shown schematically in Figure 1. For convenience, 80 nm of Cr and 1.0 μm of Cu were e-beam evaporated on a Si substrate, followed by electroless plating ∼1μm Niklad 752 nickel (1%B). The substrate was diced, then tinned on a hot plate @ 180+/- 5*C using Blackstone #1452 flux. The solder was molten for times of 30,60,120, and 240 sec. Indium was etched away in concentrated HC1 to reveal the intermetallic formation. Shown in Figure 2 is a rod-like eutectic found in the solder bulk. Debye-Scherrer x-ray powder diffraction and energy dispersive x-ray spectrometry were used to identify the phases as In/ϕ-InCu.

Interstitial water chemistry of villefranche bay sediments: Trace metal diagenesis

Pore water aliquots were taken with an in situ close interval sampler: the “Peeper”. We report here the pore water concentration profiles of TCO 2, SO 4, TH 2S, Ca and the trace metals Mn, Cu, Pb, Cd and Cr from sediments of a relatively polluted area, the Villefranche Bay, on the French Riviera (close to Nice). We investigated the major ion concentrations in order to establish geochemical mass balances of organic matter oxidation. ΔTCO 2/ΔSO 4 was <−2.0, reflecting the precipitation of calcite as confirmed by the calcium profile. Reduction of sulfate led to increasing sulfide concentrations with depth. Trace metal interstitial water concentrations decreased from 63 to 5 nM, 18 to 4 nM and 6.6 to less than 2 nM for Cu, Pb and Cr, respectively. Cd showed a different pattern with top and deep values of 0.7 nM and a minimum of 0.27 nM. Thermodynamic calculations were performed which suggest the potential formation of mineral phases such as sulfides.

Photolysis of pentacarbonyl(selenocarbonyl)chromium(0), Cr(CO)5(CSe), in an Argon matrix at 20 K

AbstractU. v. photolysis (254 and 366 nm) of Cr(CO)5(CSe) isolated in an argon matrix at ca. 20 K produces a mixture of two isomeric forms of Cr(CO)4(CSe), Cr(CO)6 and molecular CO. The two Cr(CO)4(CSe) isomers are assigned square pyramidal geometries (CSe group axial, C4v symmetry; CSe group equatorial, Cs symmetry) by comparison with the results from a previous matrix isolation i.r. study of the products formed in the u.v. photolysis of the analogous thiocarbonyl complex, Cr(CO)5(CS). On further irradiation of the Cr(CO)4(CSe) species with visible light (λ &gt; 425 nm), the parent Cr(CO)5(CSe) molecule is regenerated.