Infrared photodetachment measurements near thresholds of C−

The relative cross section has been measured in the threshold regions of the following transitions: C^?(⁴S) + hv → C³P_0,1,2) + e^? and C^?(²D) + hv → C(¹D) + e^?. The electron affinity of carbon is determined EA(C) = 1.2629 ± = 0.0003 eV, and the binding energy of the metastable C^?(²D) state with respect to the C(³P₀) ground state is 0.033 ± 0.001 eV.     

The novel chain‐like anion ∞1[NaMo8O26(mim)2]3− in (Hmim)3[NaMo8O26(mim)2] (mim is 1‐methylimidazole)

Tris(1‐methylimidazolium) bis(1‐methylimidazole)hexacosaoxidooctamolybdatesodium, (C₄H₇N₂)₃[NaMo₈O₂₆(C₄H₆N₂)₂], prepared from an aqueous solution containing Na₂MoO₄ and 1‐methylimidazole, contains the novel chain‐like anion _∞¹[NaMo₈O₂₆(mim)₂]^{3 −} (mim is 1‐methylimidazole). The [Mo₈O₂₆(mim)₂]⁴⁻ building unit, which lies across a center of inversion, is comprised of eight edge‐sharing MoO₆ and MoO₅(N_mim) octahedra. These molybdate units are interlinked by sodium, itself exhibiting a sixfold coordination with O atoms.     

Transparent luminescent layers via ionic liquid-based approach to LaPO<Subscript>4</Subscript>:RE (RE = Ce,Tb, Eu) dispersions

Transparent layers containing the highly luminescent nanophosphors LaPO₄:Ce,Tb and LaPO₄:Eu are realized by ink-jet printing on standard transparencies and black paper. The luminescent material is non-agglomerated, 15 nm in size, and applied as a dispersion in ethanol for printing. The structured layers exhibit intense green (LaPO₄:Ce,Tb) or red (LaPO₄:Eu) emission. While printing on overhead transparencies, an optical transmission of about 90% is realized. This value, in fact, is limited due to the performance of the underlying polymer material. A microwave-assisted synthesis in ionic liquids as a novel concept of synthesis is prerequisite to gain the nanoscale phosphor materials. PACS 61.46.+w; 78.67.Bf; 81.07.-b     

Adhesion of Colloidal ZnO Particles on ZnS-Type Phosphor Surfaces

Chemical and physical aspects of the adhesion of colloidal ZnO particles (d(50)=81 nm) on the surface of ZnS-type phosphors have been studied. Here, the green-emitting phosphor ZnS:Cu,Al,Cu (d(50)=5.0 μm) applied in TV screens was chosen as model compound. The ZnS material was pretreated in various ways (H(2)O, HCl, H(2)O(2)) and reacted thereafter with a suspension containing colloidal ZnO particles. Analytical investigations (SEM, ESCA) have shown that the adhesion of colloidal ZnO particles is strongly affected by the degree of hydrolysis of the ZnS surface. Electroacoustic investigations (ESA) prove that both types of surfaces, hydrolyzed ZnS as well as colloidal ZnO, are positively charged. Even so, adhesion of ZnO particles is encouraged very much under these conditions, indicating that secondary attractive forces (electrostatic interaction, chemical bonding) determine the amount of colloidal ZnO adhered on a ZnS-type phosphor. Copyright 2000 Academic Press.     

Direct measurement of lifetimes of infrared multiple-photon dissociated molecules

A beam of mass selected SF ₅ ⁺ ions is crossed with a pulsed CO₂ laser beam. The distribution of lifetimes of infrared multiple-photon pumped SF ₅ ⁺ ion-molecules prior to dissociation into SF ₄ ⁺ +F has been measured directly using a time-of-flight ion-beam technique. The data provide new information on the distribution of the total internal energy of molecules excited by absorption of infrared radiation.     

Photodetachment measurements of H− near threshold

From the measured threshold dependance of the cross section the electron affinity of H is found to be 0.7539 eV ±0.002 eV.