Magnetic field effect on tunnel ionization of deep impurities by terahertz radiation

A suppression of tunnelling ionization of deep impurities in terahertz frequency electric fields by a magnetic field is observed. It is shown that the ionization probability at external magnetic field, B, oriented perpendicular to the electric field of terahertz radiation, E, is substantially smaller than that at B || E. The effect occurs at low temperatures and high magnetic fields

Molecular Conductors from Neutral-Radical Charge-Transfer Salts:Preparation and Characterization of an Iodine-Doped Hexagonal Phase of 1,2,3,5-Dithiadiazolyl ([HCN2S2]∙)

Sublimation of 1,2,3,5-dithiadiazolyl in vacuo affords a triclinic phase of the dimer [HCN2S2]2. The crystals belong to the space group P¯1, a = 6.816(3), b = 13.940(2), c = 14.403(3) Å, α = 116.830(14), β = 98.64(3), γ = 99.18(3)°, FW = 212.4 (for [HCN2S2]2·[N2]0.08) Z = 6. The crystal structure consists of stacked dimers, with three dimers per asymmetric unit. Pairs of asymmetric units, related by an inversion center, generate a pinwheel motif consisting of six dimers. The columnar structure associated with these pinwheels forms close-packed sets of “molecular tubes”. Cosublimation of the radical in the presence of iodine in the mole ratio (HCN2S2:I = 5:1) yields an iodine-doped hexagonal phase of composition [HCN2S2]6[I]1.1. Crystals of this material belong to the space group P61, a = b = 14.132(16), c = 3.352(5) Å, FW = 128.20, Z = 6. The crystal structure consists of sixfold pinwheels in which the now evenly spaced HCN2S2 rings form a spiral about the 61 axis. The iodine atoms lie within the columnar cavity of the pinwheels in a disordered array wrapped tightly about the sixfold screw axis. The single-crystal conductivity of the doped material is 15 S cm-1 at room temperature. Raman spectroscopic and magnetic susceptibility measurements on the doped material are reported

A 1-Year Prospective French Nationwide Study of Emergency Hospital Admissions in Children and Adults with Primary Immunodeficiency.

PURPOSE: Patients with primary immunodeficiency (PID) are at risk of serious complications. However, data on the incidence and causes of emergency hospital admissions are scarce. The primary objective of the present study was to describe emergency hospital admissions among patients with PID, with a view to identifying "at-risk" patient profiles. METHODS: We performed a prospective observational 12-month multicenter study in France via the CEREDIH network of regional PID reference centers from November 2010 to October 2011. All patients with PIDs requiring emergency hospital admission were included. RESULTS: A total of 200 admissions concerned 137 patients (73 adults and 64 children, 53% of whom had antibody deficiencies). Thirty admissions were reported for 16 hematopoietic stem cell transplantation recipients. When considering the 170 admissions of non-transplant patients, 149 (85%) were related to acute infections (respiratory tract infections and gastrointestinal tract infections in 72 (36%) and 34 (17%) of cases, respectively). Seventy-seven percent of the admissions occurred during winter or spring (December to May). The in-hospital mortality rate was 8.8% (12 patients); death was related to a severe infection in 11 cases (8%) and Epstein-Barr virus-induced lymphoma in 1 case. Patients with a central venous catheter (n = 19, 13.9%) were significantly more hospitalized for an infection (94.7%) than for a non-infectious reason (5.3%) (p = 0.04). CONCLUSION: Our data showed that the annual incidence of emergency hospital admission among patients with PID is 3.4%. The leading cause of emergency hospital admission was an acute infection, and having a central venous catheter was associated with a significantly greater risk of admission for an infectious episode

Magnetic field effect on tunnel ionization of deep impurities by far-infrared radiation

The probability of electron tunneling from a bound to a free state in an alternating electric and a constant magnetic field is calculated in the quasiclassical approximation. It is shown that the magnetic field reduces the probability of electron tunneling. The application of the external magnetic field perpendicular to the electric field reduces the ionization probability at high magnetic fields, when cyclotron resonance frequency becomes larger than reciprocal tunneling time. The increase of electric field frequency to values larger than the same reciprocal tunneling time enhances the influence of magnetic field

Magnetic-field-dependent energy levels in a highly anisotropic electronic material

Contains fulltext : 112818.pdf (publisher's version ) (Open Access

FIR-spectroscopy of the FI-SDW excitation spectrum in a quasi-1D organic conductor

Contains fulltext : 29389.pdf (publisher's version ) (Open Access

Far-infrared spectroscopy of the field-induced spin-density-wave gap in (TMTSF)2ClO4

Contains fulltext : 112805.pdf (publisher's version ) (Open Access

C60 thin film transistors

N-channel field effect transistors with excellent device characteristics have been fabricated by utilizing C60 as the active element. Measurements on C60 thin films in ultrahigh vacuum show on-off ratios as high as 10e6 and field effect mobilities up to 0.08 cm2/V s.

Iodine Charge-Transfer Salts of Benzene-Bridged Bis(1,2,3,5-diselenadiazolyl) Diradicals. Electrocrystallization and Solid-State Characterization of 1,3- and 1,4-[(Se2N2C)C6H4(CN2Se2)][I]

Electroreduction of 1,3- and 1,4-benzene-bridged bis(diselenadiazolium) salts [1,4-Se][SbF6]2 and [1,4-Se][SbF6]2 in acetonitrile, at a Pt wire and in the presence of iodine affords the 1:1 charge-transfer salts [1,4-Se][I] and [1,3-Se][I]. Crystals of [1,4-Se][I] belong to the monoclinic space group C2/m, with FW = 598.9, a = 10.586(2), b = 16.713(2), c = 3.5006(14) Å, β = 104.26(2)°, V = 600.2(3) Å3, Z = 2. Crystals of [1,3-Se][I] belong to the orthorhombic space group Ima2, with FW = 598.9, a = 28.489(7), b = 3.543(2), c = 12.283(2) Å, V = 1239.8(8) Å3, Z = 4. In the presence of an excess of iodine, electrocrystallization of [1,4-Se]2+ affords the mixed iodide/triiodide salt [1,4-Se][I][I3], space group C2/c, FW = 979.59, a = 12.862(3), b = 15.063(2), c = 9.028(3) Å, β = 100.62(2)°, V = 1719.1(7) Å3, Z = 4. The structures of the two 1:1 compounds consist of perfectly superimposed stacks of molecular units interspersed by columns of disordered iodines. Interstack contacts in both structures are limited, indicative of 1-dimensional electronic structures. Variable-temperature single-crystal conductivity measurements on [1,4-Se][I] reveal weakly metallic behavior at room temperature, with a phase transition to a semiconducting state occurring at about 240 K. Magnetic susceptibility measurements on [1,4-Se][I] are consistent with the conductivity data; the magnetic susceptibility of [1,3-Se][I] behaves similarly. The crystal structures and transport properties are discussed in light of extended Hückel band structure calculations.

Charge-Transfer Complexes of 4-Phenyl-1,2,3,5-dithiadiazolyl and 4-Phenyl-1,2,3,5-diselenadiazolyl with Iodine. Preparation and Solid-state Characterization of [PhCN2E2]3[I3] (E = S, Se) and [PhCN2S2][I3]

The 1:1 reaction of the heterocyclic radicals [PhCN2E2]∙ (E = S, Se) and iodine affords the mixed valence salts [PhCN2E2]3[I3], while reaction of PhCN2S2 with an excess of iodine affords the simple salt [PhCN2S2][I3]; the solid-state structures of these complexes have been determined by X-ray crystallography. Crystals of both of the mixed valence compounds belong to the triclinic space group P¯1; for E = S, a = 10.278(4), b = 11.508(2), c = 13.333(4) Å, α = 114.97(2), β = 99.21 (3), γ = 92.65(2)°, FW = 308.15, Z = 6; for E = Se, a = 10.368(6), b = 10.818(8), c = 13.421(8) Å, α = 80.64(5), β = 81.20(5), γ = 75.18(6)°, FW = 401.95, Z = 6. Crystals of the simple salt belong to the monoclinic space group P21/a; a = 7.366(4), b = 11.734(1), c = 15.166(2) Å, β = 95.92(3)°, FW = 1303.99(7), Z = 4. In each of the mixed valence compounds the molecular (asymmetric) unit consists of a trimeric [PhCN2E2]3+ cation and an associated triiodide anion. Within the cations the mean interannular E-E contacts are 3.181/3.377 Å (E = S/Se). The packing patterns of the two compounds show important differences. For E = S the crystal structure does not exhibit stacking of the trimeric molecular building blocks, but for E = Se the trimer units form dovetailed stacks in which consecutive layers are oriented in a trans-antipodal fashion. This arrangement introduces close interannular contacts between the blocks along the stack, as well as close lateral contacts. The asymmetric unit of [PhCN2S2][I3] consists of a single PhCN2S2+ cation and an associated triiodide anion; there are no unusual stacking features. The magnetic and conductivity properties of [PhCN2Se2]3[I3] are reported, and the results discussed in the light of extended Hückel band structure calculations.