Infrared multiple-photon dissociation of N2H4 and CH3NH2 fluence dependence of the production of NH2

The multiple-photon dissociation of N₂H₄ and CH₃NH₂ by pulsed CO₂ laser light to produce NH₂(X?²B_I has been studied using the laser-induced fluorescence detection method. The relative NH₂ yield, represented by the fluorescence signal, has been measured as a function of the fluence from the threshold at about 0.1 J/cm² to about 100 J/cm², at different CO₂-laser lines and at pressures down to 10^?4 Torr.     

Zur Kenntnis von cis-Natriumhyponitrit

To the Knowledge of cis-Sodium Hyponitrite Surprisingly, cis-sodium hyponitrite can be prepared by reacting gaseous N₂O and solid Na₂O. For the first time, the structure of a simple salt of cis hyponitrous acid has been determinated unambigously. According to an abinitio structure determination based on powder data, cis-Na₂N₂O₂ crystallizes monoclinic (P2₁/c, a = 5.107(1); b = 9.211(1); c = 6.159(1) Å; β = 97.91(1)°; Z = 4). Results of spectroscopic investigations (vibrational spectroscopy, ¹⁵N-MAS-NMR) agree with the symmetry of the cis-N₂O₂^2? anion as it has been proved by the crystal structure. Consider able differences regarding some chemical and physical properties have been observed for samples of cis-Na₂N₂O₂ synthesized via different routes.     

Magnetic properties of erbium iron garnet in high magnetic fields up to 150kOe

The magnetic properties of single crystals of erbium iron garnet (ErIG) were studied in applied fields up to 150kOe between 1.4 and 300K. At low temperature, the macroscopic easy direction of the bulk magnetization is [100]; below the compensation temperature (80±2K), the magnetization presents non-linear field evolution. On the assumption of an isolated ground doublet, the anisotropy constantsK _i (i=1,2) of ErIG are given byK _i (Er)+K _i (YIG); theK _i are calculated as a function of theG andg tensor components. It is worthwhile noting that theK _i (Er) are strongly temperature dependent; so at low temperature the anisotropy of the garnet is determined by the rare earth ions, while in the 50 K regionK ₁(Er) becomes comparable toK ₁(YIG) with the opposite sign which results in a very weak anisotropy of the garnet. Above 50 K,K ₁(YIG) is predominant and the Fe³⁺ ions determine the garnet anisotropy.     

Drei Heterocubanartige (MII4O4)‐Typ Verbindungen (M = FeII,CoII, NiII)

By reaction of M^IICl₂·x H₂O (M = Fe (x = 4), Co, Ni (x = 6)) and LiOH·H₂O in diethylene glycol (DEG) rod‐like crystals of the composition M^II₄Cl₄(OCH₂CH₂OCH₂CH₂OH)₄ are formed. According to X‐ray diffraction data obtained by both, single crystals and powders, the Co^II and Ni^II compounds crystallize monoclinic with C2/c (Co^II₄Cl₄(OCH₂CH₂OCH₂CH₂OH)₄ ( 1 ): a = 2084.1(4), b = 919.0(2), c = 1754.0(4) pm, β = 124.3(1)°, Z = 4; Ni^II₄Cl₄(OCH₂CH₂OCH₂CH₂OH)₄ ( 2 ): a = 2055.2(4), b = 932.1(2), c = 1727.4(4) pm, β = 125.2(1)°, Z = 4), whereas Fe^II₄Cl₄(OCH₂CH₂OCH₂CH₂OH)₄ ( 3 ) crystallizes tetragonal with (a = 1251.4(2), c = 915.3(2) pm, Z = 2). All compounds exhibit analogous molecular structures which are built of a heterocubane‐type core consisting of four metal ions and four deprotonated oxygen atoms of four coordinated diethylene glycol molecules. Neutrality of charge is realized by additional coordination of four chloride anions. In addition to the structural characterization, the thermal and magnetical properties of the title compounds are investigated in detail.     

Exclusive radiative and electroweak b\to d and b\to s penguin decays at NLO

We provide standard model expectations for the rare radiative decays , and , and the electroweak penguin decays and at the next-to-leading order (NLO), extending our previous results to transitions. We consider branching fractions, isospin asymmetries and direct CP asymmetries. For the electroweak penguin decays, the lepton-invariant mass spectrum and forward-backward asymmetry is also included. Radiative and electroweak penguin transitions in are mainly interesting in the search for new flavor-changing neutral current interactions, but in addition the decays provide constraints on the CKM parameters . The potential impact of these constraints is discussed.Received: 16 January 2005, Published online: 16 March 2005 Corresponding author: Th. Feldmann