Tungsten allylimido complexes Cl4(RCN)W(NC3H5) as single-source CVD precursors for WNxCy thin films. Correlation of precursor fragmentation to film properties

A mixture of the tungsten allylimido complexes Cl(4)(RCN)W(NC(3)H(5)) (3a, R = CH(3) and 3b, R = Ph) was tested as a single-source precursor for growth of tungsten nitride (WN(x)) or carbonitride (WN(x)C(y)) thin films. Films deposited from 3a,b below 550 degrees C contained amorphous beta-WN(x)C(y), while those deposited at higher temperatures were polycrystalline. Film growth rates from 3a,b ranged from 5 to 10 A/min over a temperature range of 450-650 degrees C, and the apparent activation energy for film growth was 0.15 eV. A plot of the E(a) values for deposition from Cl(4)(RCN)W(NR') [R' = Ph, (i)Pr, allyl] against the N-C imido bond strengths for the analogous amines R'NH(2) is linear, implicating cleavage of the N-C bond as the rate-determining step in film growth. The correlation of mass spectral fragmentation patterns for Cl(4)(RCN)W(NR') with film properties such as nitrogen content supports the significance of facile N-C bond cleavage in film growth.     

Über die Rolle der Flammentemperatur bei der flammenphotometrischen Analyse der Alkalimetalle

Zusammenfassung Einige Störungserscheinungen bei der flammenphotometrischen Analyse von Alkalimetallen wurden mit Rücksicht auf die Vorgänge in der Flamme theoretisch behandelt und gedeutet. Durch kontrollierte Flammentemperaturänderung konnte die Auswirkung von Anregung, Ionisation, thermischer Dissoziation und anderen Einzelvorgängen auf die Emission eingehender geklärt werden. Zur flammenphotometrischen Analyse werden unmittelbar in die Flamme sprühende Zerstäuberbrenner und Apparate mit Prismen bzw. Gittern empfohlen, weil bei solchen Einrichtungen einige schwer überblickbare, störende, kolloidchemische Parameter wegfallen. Die Sicherstellung einer ruhigeren Flamme mit Hilfe von Nebelabscheidern verliert bei Einrichtungen, die nur einen Teil der Flamme auf den 0,01 bis 1 mm breiten Spalt des Monochromators abbilden, sowieso ihren Zweck. Bei Zerstäubern mit Abscheider zeigt sich der Alkoholeffekt, das heißt die Form der Alkoholkonzentrations-Emissionskurve als von der Oberflächenspannungsänderung abhängig, obwohl sie sich aus der Überlagerung mehrerer Parameter ergibt. Auch bei den bekannten Eichkurven, mit deren Hilfe die günstigsten Brennund Zerstäubergasmischungen eingestellt werden, spielt neben der Zerstäubungsgeschwindigkeit die Flammentemperatur die überwiegende Rolle.Lithium und Natrium werden in der Knallgasflamme nur wenig ionisiert, so daß sie bei der flammenphotometrischen Analyse der Alkalimetalle nicht stören und nicht gestört werden. Kalium, Rubidium und Caesium erfahren dagegen in dieser Flamme eine bedeutende Ionisation, wodurch die Emission durch gegenseitige Zurückdrängung der Ionisation erhöht wird. Durch Zumischung von Stickstoff zu dem als Zerstäubergas benutzten Sauerstoff kann die Flammentemperatur ohne Änderung der übrigen Parameter um mehr als 1000° C herabgesetzt werden, womit die durch Ionisation verursachte Störung aufgehoben werden kann und die analytische Bestimmung der drei letzteren Elemente nebeneinander möglich wird. Die Wirkung der Flammentemperatur auf die Form der Eichkurven ist besonders beim Caesium auffallend, dessen Eichkurve infolge Temperaturerniedrigung aus einer S-förmigen in eine solche mit Sättigungscharakter übergeht. Der Anioneneinfluß wird auf die thermische Dissoziation der versprühten oder sich in der Flamme bildenden Salze zurückgeführt.

---

Summary Several disturbing phenomena encountered in the flame photometric analysis of alkali metals were studied theoretically and explained with respect to the processes in the flame. The effect on the emission of excitation, ionization, thermal dissociation and other individual processes were cleared up to a considerable extent. Atomizing burners functioning in the immediate vicinity of the flame were recommended for flame photometric determinations, and also equipment provided with prisms or lattices, since such devices eliminate several disturbing colloid chemical parameters, which are difficult to survey. The obtaining of a quiet flame with the aid of vapor deflectors has no purpose in any case with devices which reflect only a part of the flame on the 0.01 to 1 mm wide slit of the monochromator. When the atomizing is done in connection with a deflector, the alcohol effect appears, namely, the form of the alcohol concentration-emission curve becomes dependent on the change in surface tension, although it results from the overlapping of several parameters. Likewise, in addition to the atomizing rate, the flame temperature plays the dominant role in the familiar calibration curves, with whose aid the most favorable combustion and atomizing mixtures are set up.Lithium and sodium are only slightly ionized in the oxyhydrogen flame, so they do not interfere in the photometric determination of the alkali metas and vice versa. In contrast, potassium, rubidium and cesium undergo considerable ionization in this flame, whereby the emission is increased through mutual repression of the ionization. By mixing nitrogen with the atomizing gas (oxygen), the flame temperature can be lowered by more than 1000° without change of the other parameters, and this averts the disturbance due to the ionization and so makes possible the analytical determination of the three latter elements. The effect of the flame temperature on the form of the calibration curves is especially striking in the ease of cesium, whose calibration curve, because of temperature lowering, changes from an S-form into one having a saturation character. The anion influence is, ascribed to the thermal dissociation of the sprayed salts or of those that form in the flame.

---

Résumé Sur la base des phénomènes qui se produisent dans les flammes, on procède à une étude théorique et à une interprétation de quelques perturbations constatées lors de l'analyse des métaux alcalins par photométrie de flamme. Il a été possible de déterminer l'influence exacte de l'excitation, de l'ionisation, de la dissociation thermique et d'autres processus élémentaires par variation contrôlée de la température de flamme. Pour l'analyse photométrique les auteurs recommandent l'emploi de brûleurs pulvérisateurs permettant une projection directe dans la flamme ainsi que d'appareils à prismes ou à réseaux: on évite ainsi des perturbations imputables à des phénomènes de chimie colloïdale qu'il est difficile de discriminer. L'emploi d'un séparateur de brouillard permettant l'obtention d'une flamme calme est sans objet lorsqu'on emploie des monochromateurs de largeur de fente de 0,01 à 1 mm qui ne fournissent que l'image d'une partie de la flamme. L'effet »d'alcool« se manifeste d'autre part lorsqu'on emploie des pulvérisateurs équipés de séparateurs, dans la mesure où la forme de la courbe d'émission en fonction des concentrations alcooliques se modifie suivant les variations de la tension superficielle, bien qu'elle résulte de la superposition des effets de plusieurs paramètres. La vitesse de pulvérisation et la température de la flamme jouent également un rôle prépondérant lors de l'établissement des courbes d'étalonnages classiques qui permettent de régler à leur composition optimum les mélanges de gaz combustible et de gaz de pulvérisation.Le lithium et le sodium étant fort peu ionisés dans la flamme du gaz tonnant, il en résulte que lors de l'analyse des métaux alcalins par photométrie de flamme ils n'apportent ni ne subissent aucune perturbation. Par contre, le potassium, le rubidium et le césium sont sensiblement ionisés dans cette flamme de sorte que l'émission est élevée par l'effet de rétrogradation réciproque de l'ionisation. L'addition d'azote à l'oxygène employé comme gaz de pulvérisation permet d'abaisser la température de la flamme à une valeur supérieure à 1000° C sans apporter de variations parmi les autres paramètres: il s'ensuit la disparition des perturbations dues à l'ionisation et la possibilité do doser chacun des trois derniers éléments en présence des autres. L'effet de la température de flamme sur la forme de la courbe d'étalonnage est particulièrement remarquable dans le cas du césium: un abaissement de la température transforme en effet une courbe en S en une courbe correspondant à un phénomène de saturation. L'influence des anions est attribuée à la dissociation thermique des sels qui sont projetés dans la flamme ou qui s'y forment.

     

Beitr?ge zur Hochfrequenztitration des Aluminiums

Zusammenfassung Verfasser untersuchten die Hochfrequenztitration des Aluminiums mit Bariumhydroxyd, Natriumhydroxyd und Triäthylamin als Maßlösungen. Es wird festgestellt, daß die während der Bildung der Aluminiumisopolybase auftretenden Brechungspunkte für die Bestimmung der Aluminiumkonzentration nicht geeignet sind. Jene Schnittpunkte welche die Abscheidung des Aluminiumhydroxyds und die Bildung des Aluminats anzeigen, können im Falle starker Basen nur schwierig ausgewertet werden. Bessere Auswertungsmöglichkeiten ergeben sich bei Anwendung von Triäthylamin, doch dauert die Titration zu lange.Ein rasch ausführbares indirektes Hochfrequenzverfahren für die Bestimmung des Aluminiums ergibt sich, wenn man die saure aluminiumhaltige Lösung mit Bariumhydroxydlösung versetzt und den zugegebenen Laugeüberschuß mit Essigsäure zurückmißt. Beim Endpunkt der Rücktitration liegt das Aluminium als Aluminat vor.     

Norditerpenoid Alkaloids from the Aerial Parts of Aconitum cochleare Woroschin

From the aerial parts of Aconitum cochleare Woroschin, two new norditerpenoid alkaloids named aconitilearine ( 1 ) and N‐deethylmethyllycaconitine ( 2 ) were isolated along with the eight known norditerpenoid alkaloids 3 – 10 . The structures for the new compounds were established on the basis of ¹H, ¹³C, DEPT, homonuclear ¹H,¹H‐COSY, NOESY, HSQC, and HMBC NMR studies.     

When size matters: exploring the potential of aminocyclopropenium cations as head groups in triphenylene-derived ionic liquid crystals in comparison with guanidinium and ammonium units

The influence of the size of a single ionic head group on the mesomorphic properties of hexaalkoxytriphenylenes was investigated by synthesising three derivatives with increasing head group diameter. The derivatives were investigated with optical polarising microscopy (POM), differential scanning calorimetry (DSC) and X-ray scattering (WAXS, SAXS). For the derivative with the small trimethylammonium head group, an enantiotropic mesophase was found. The derivative with the bigger tetramethylguanidine head group only showed a monotropic phase and the derivative with the largest bisdiisopropylaminocyclopropenium head group displayed no liquid crystaline properties at all.     

A New Diterpenoid Alkaloid from the Roots of a White‐Flowering Aconitum orientale Sample

From the roots of a white‐flowering Aconitum orientale Miller sample, collected in Artvin‐?av?at, Turkey, a new diterpenoid alkaloid named aconitorientaline ( 1 ) was isolated, along with the known diterpenoid alkaloids septentiriodine, lappaconitine, finaconitine, ranaconitine, puberanidine and delstaphinine (Fig.). The structure of 1 was established on the basis of ¹H‐ and ¹³C‐NMR, DEPT, ¹H,¹H‐COSY, NOESY, HSQC, and HMBC studies. All the known compounds were identified by comparison of their ¹H‐ and ¹³C‐NMR data and co‐TLC behavior with those of authentic samples.     

Use of liquid chromatography coupled to low- and high-resolution linear ion trap mass spectrometry for studying the metabolism of paynantheine, an alkaloid of the herbal drug Kratom in rat and human urine

The Thai medicinal plant Mitragyna speciosa (Kratom in Thai) is misused as a herbal drug of abuse. During studies on the main Kratom alkaloid mitragynine (MG) in rats and humans, several dehydro analogs could be detected in urine of Kratom users, which were not found in rat urine after administration of pure MG. Questions arose as to whether these compounds are formed from MG only by humans or whether they are metabolites formed from the second abundant Kratom alkaloid paynantheine (PAY), the dehydro analog of MG. Therefore, the aim of the presented study was to identify the phase I and II metabolites of PAY in rat urine after administration of the pure alkaloid. This was first isolated from Kratom leaves. Liquid chromatography–linear ion trap mass spectrometry provided detailed structure information of the metabolites in the MSⁿ mode particularly with high resolution. Besides PAY, the following phase I metabolites could be identified: 9-O-demethyl PAY, 16-carboxy PAY, 9-O-demethyl-16-carboxy PAY, 17-O-demethyl PAY, 17-O-demethyl-16,17-dihydro PAY, 9,17-O-bisdemethyl PAY, 9,17-O-bisdemethyl-16,17-dihydro PAY, 17-carboxy-16,17-dihydro PAY, and 9-O-demethyl-17-carboxy-16,17-dihydro PAY. These metabolites indicated that PAY was metabolized via the same pathways as MG. Several metabolites were excreted as glucuronides or sulfates. The metabolism studies in rats showed that PAY and its metabolites corresponded to the MG-related dehydro compounds detected in urine of the Kratom users. In conclusion, PAY and its metabolites may be further markers for a Kratom abuse in addition of MG and its metabolites.     

The experimental and simulated LET spectrum and charge spectrum from CR-39 detectors exposed to irons near CRaTER at BNL

Human will be sooner or later return to the moon and will eventually travel to the planets near Earth. Space radiation hazards are an important concern for human space flight in deep space where galactic cosmic rays (GCR) and solar energetic particles are dominated and radiation is much stronger than that in LEO (Low Earth Orbit) because in deep space there is no magnetosphere to screen charged particle and no big planet nearby to shadow the spacecraft.Research indicates that the impact of particle radiation on humans depends strongly on the particles' linear energy transfer (LET) and the radiation risk is dominated by high LET radiation. Therefore, radiation research on high LET should be emphasized and conducted systematically so as to make radiation risk as low as reasonably achievable (ALARA) for astronauts.Radiation around the moon can be measured with silicon detectors and/or CR-39 plastic nuclear track detectors (PNTDs). At present stage the silicon detectors are one of the preferred active dosimeters which are sensitive to all LET and CR-39 detectors are the preferred passive dosimeters which are sensitive to high LET (≥5 keV/μm water). CR-39 PNTDs can be used as personal dosimeters for astronauts. Both the LET spectrum and the charge spectrum for charged particles in space can be measured with silicon detectors and CR-39 detectors.Calibrations for a detector system combined with the silicon detectors CRaTER (Cosmic Rays Telescope for the Effects of Radiation) from Boston University and Massachusetts Institute of Technology, and the CR-39 PNTDs from JSC (Johnson Space Center) – SRAG (Space Radiation Analysis Group) were conducted by exposing the detector system to the accelerator generated protons and heavy ions. US space mission for the radiation measurement around the moon using CRaTER was carried out in 2009.Results obtained from the calibration exposures indicate an excellent agreement between LET spectrum and charge spectrum measured with CR-39 detectors and simulated with PHITS (Particle and Heavy Ion Transport System).This paper introduces the LET spectrum method and charge spectrum method using CR-39 PNTDs and the Monte Carlo simulation method for CR-39 detectors, presents and compares the results measured with CR-39 PNTDs and simulated for CR-39 detectors exposed to heavy irons (600 MeV/n) in BNL (Brookhaven National Laboratory) in front and behind the CRaTER.     

Jet quenching from soft QCD scattering in the quark–gluon plasma

We show that partons traversing a quark–gluon plasma can lose substantial amounts of energy also by scatterings, and not only through medium-induced radiation as mainly considered previously. Results from Monte Carlo simulations of soft interactions of partons, emerging from a hard scattering, through multiple elastic scatterings on gluons in an expanding relativistic plasma show a sizeable jet quenching which can account for a substantial part of the effect observed in RHIC data.     

Self-Assembly of Aminocyclopropenium Salts: En Route to Deltic Ionic Liquid Crystals

Aminocyclopropenium ions have raised much attention as organocatalysts and redox active polymers. However, the self-assembly of amphiphilic aminocyclopropenium ions remains challenging. The first deltic ionic liquid crystals based on aminocyclopropenium ions have been developed. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction provided insight into the unique self-assembly and nanosegregation of these liquid crystals. While the combination of small headgroups with linear p-alkoxyphenyl units led to bilayer-type smectic mesophases, wedge-shaped units resulted in columnar mesophases. Upon increasing the size and polyphilicity of the aminocyclopropenium headgroup, a lamellar phase was formed.