Torsional bands of hydroxylamine

Infrared absorption spectrum of NH₂OH has been observed in its gaseous state, and the fine structures of the bands at 386 and 751 cm^?1 assignable, respectively, to the fundamental and overtone of the torsional vibration of this molecule have been examined. Band center frequencies for the n = 1 ← 0, 2 ← 1, 3 ← 2, 2 ← 0, and 3 ← 1 transitions (where n is the vibrational quantum number of the torsional oscillation) have been determined to be 386.2, 365.1, 346.3, 751.2, and 711.3 cm^?1, respectively. On the basis of these data, a discussion is given on the internal-rotation potential function.     

Some unusual reactions of dimers of F-propene with thiols

Reactions of $\text{F}$-2- and -4-methly-2-pentenes with thiols were found to involve an oxidation-reduction system. 1,4-Elimination of sulfenyl fluorides from thio-substituted perfluoroolefins to form 1,3-dienes and disulfides is suggested as the reaction pathway.     

Tribochemical reaction dynamics of phosphoric ester lubricant additive by using a hybrid tight-binding quantum chemical molecular dynamics method

To study the atomistic behavior of the phosphoric ester molecule on the nascent Fe surface under boundary lubrication conditions, we adopted a hybrid tight-binding quantum chemical molecular dynamics method. First, we investigated chemical interactions between phosphoric ester and the nascent Fe surface. Phosphoric ester was shown to interact with the nascent Fe surface, forming both covalent and ionic bonds. Formation and dissociation dynamics of covalent bonds during tribochemical reaction was clearly observed during the simulation. The effect of friction condition on the tribochemical reaction dynamics was then studied, and it was indicated that friction would influence the formation and the dissociation of covalent bonds. By using a hybrid tight-binding quantum chemical molecular dynamics method, we obtained insights on initial tribochemical reaction processes for the formation of tribofilm from the phosphoric ester molecule on the nascent Fe surface.     

Enantio- and diastereoselective hydrogenation via dynamic kinetic resolution by a cationic iridium complex in the synthesis of beta-hydroxy-alpha-amino acid esters

Anti-selective asymmetric hydrogenation of alpha-amino-beta-keto esters via dynamic kinetic resolution under low hydrogen pressure has been achieved by an easily-handled cationic iridium complex with tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BARF) as a counterion.     

Raman Scattering Tensors in Biological Molecules and Their Assemblies

INTRODUCTION

The tensor associated with a Raman band plays an important role in determining the band intensity and its structural significance. Each Raman tensor interrelates two electric vectors, that of the exciting radiation (i.e. laser photon) and that of the Raman scattered radiation (i.e. the inelastically scattered photon which results from the exchange of a vibrational quantum between the exciting photon and the molecule). The Raman tensor is obtained formally as the first derivative of the molecular polarizability tensor, the derivative being taken with respect to the vibrational normal coordinate. In other words, the Raman tensor associated with a vibrational Raman band is an indicator of how the polarizability of the molecule oscillates with the molecular normal mode of vibration.     

Transverse wave generation mechanism in rotating detonation

Detonation engines are expected to be included in a number of aerospace thrusters in the future. Several types of detonation engines are currently under examination, including the rotating detonation engine (RDE). Although the RDE has been explored experimentally, its rotating detonation propagation mechanism is not well understood. This paper clarifies the detonation mechanism and dynamics of the RDE by 2D and 3D simulation using compressible Euler equations with a full chemical reaction mechanism of H₂/O₂ and H₂/Air, especially from the triple-point and transverse detonation points of view. A total variation diminishing (TVD) scheme is used for the mixture of H₂/Air, and an advection upwind splitting method difference vector (AUSMDV) scheme is used for the mixture of H₂/O₂. The use of an AUSMDV scheme provides a much clearer detonation structure than does the TVD scheme. We focus on the complex interaction mechanism of the detonation front and burned mixture gases. We found out that at this interaction point, an unreacted gas pocket appears and ignites periodically to generate transverse waves at the detonation front and maintain detonation propagation.     

Optical observation of ion displacement in pyroelectric BaMnF4

Two anomalous behaviors are observed in the Raman spectra of BaMnF₄ at room temperature. One is that the number of Raman lines is smaller than that expected for the orthorhombic crystal structure with C _2ν ¹² symmetry, the other is that, of the b(aa)c, a(bb)c, and b(cc)a scattering geometries giving the same A₁-symmetry spectrum, the number of Raman lines in the b(aa)c spectrum is considerably smaller than those in the other two spectra. It is suggested that rotation of MnF₆ octahedra about c-axis occurring in the orthorhombic phase is responsible for the former behavior, and Ba²⁺-ion displacement along a-axis for the latter one.