Two monoclinic polymorphs
of [Ag(NH
3
)
2
]MnO
4
containing a unique
coordination mode of permanganate ions
were prepared, and the high-temperature polymorph was used as a precursor
to synthesize pure AgMnO
2
. The hydrogen bonds between the
permanganate ions and the hydrogen atoms of ammonia were detected
by IR spectroscopy and single-crystal X-ray diffraction. Under thermal
decomposition, these hydrogen bonds induced a solid-phase quasi-intramolecular
redox reaction between the [Ag(NH
3
)
2
]
+
cation and MnO
4
–
anion
even before losing the ammonia ligand or permanganate oxygen atom.
The polymorphs decomposed into finely dispersed elementary silver,
amorphous MnO
x
compounds, and H
2
O, N
2
and NO gases. Annealing the primary decomposition
product at 573 K, the metallic silver reacted with the manganese oxides
and resulted in the formation of amorphous silver manganese oxides,
which started to crystallize only at 773 K and completely transformed
into AgMnO
2
at 873 K.
The behavior of single layer van der Waals (vdW) materials is profoundly influenced by the immediate atomic environment at their surface, a prime example being the myriad of emergent properties in artificial heterostructures. Equally significant are adsorbates deposited onto their surface from ambient. While vdW interfaces are well understood, our knowledge regarding atmospheric contamination is severely limited. Here we show that the common ambient contamination on the surface of: graphene, graphite, hBN and MoS2 is composed of a self-organized molecular layer, which forms during a few days of ambient exposure. Using low-temperature STM measurements we image the atomic structure of this adlayer and in combination with infrared spectroscopy identify the contaminant molecules as normal alkanes with lengths of 20-26 carbon atoms. Through its ability to self-organize, the alkane layer displaces the manifold other airborne contaminant species, capping the surface of vdW materials and possibly dominating their interaction with the environment.
H+3 is the simplest triatomic molecule and plays an important role in laboratory and astrophysical plasmas. It is very stable both in terms of its electronic and nuclear degrees of freedom but is difficult to study in depth in the laboratory due to its ionic nature. In this communication, experimental results are presented for the strong field dissociation of the isotopic analogue D+3, using 30 fs, 800 nm laser pulses with intensities up to 1016 W cm−2. By employing a novel experimental set-up, ions were confined in an electrostatic ion trap so that dissociation of the molecule could be studied as it radiatively cools. It was determined that dissociation could only be observed for molecules in ro-vibrational states relatively close to the dissociation limit, while more tightly bound states demonstrated remarkable stability in even the strongest fields.
Deformation behaviour of rolled AZ31 sheets that were subjected to the accumulative roll bonding was investigated. Substantially refined microstructure of samples was achieved after the first and second pass through the rolling mill. Sheets texture was investigated using an X-ray diffractometer. Samples for tensile tests were cut either parallel or perpendicular to the rolling direction. Tensile tests were performed at temperatures ranging from room temperature up to 300 °C. Tensile plastic anisotropy, different from the anisotropy observed in AZ31 sheets by other authors, was observed. This anisotropy decreases with an increasing number of rolling passes and increasing deformation temperature. Grain refinement and texture are the crucial factors influencing the deformation behaviour.
An electrostatic trapping scheme for use in the study of light-induced dissociation of molecular ions is outlined. We present a detailed description of the electrostatic reflection storage device and specifically demonstrate its use in the preparation of a vibrationally cold ensemble of deuterium hydride (HD + ) ions. By interacting an intense femtosecond laser with this target and detecting neutral fragmentation products, we are able to elucidate previously inaccessible dissociation dynamics for fundamental diatomics in intense laser fields. In this context, we present new results of intense field dissociation of HD + which are interpreted in terms of recent theoretical calculations.
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