Solvay

About: Solvay is a company organization based out in Brussels, Belgium. It is known for research contribution in the topics: Catalysis & Polymer. The organization has 6083 authors who have published 7004 publications receiving 105745 citations.

Space-time formulation of quantum transitions

Abstract: In a previous paper we have studied dressed excited states in the Friedrichs model, which describes a two-level atom interacting with radiation. In our approach, excited states are distributions (or generalized functions) in the Liouville space. These states decay in a strictly exponential way. In contrast, the states one may construct in the Hilbert space of wave functions always present deviations from exponential decay. We have considered the momentum representation, which is applicable to global quantities (trace, energy transfer). Here we study the space-time description of local quantities associated with dressed unstable states, such as, the intensity of the photon field. In this situation the excited states become factorized in Gamow states. To go from local quantities to global quantities, we have to proceed to an integration over space, which is far from trivial. There are various elements that appear in the space-time evolution of the system: the unstable cloud that surrounds the bare atom, the emitted real photons and the ``Zeno photons,'' which are associated with deviations from exponential decay. We consider a Hilbert space approximation to our dressed excited state. This approximation leads already to decay close to exponential in the field surrounding the atom, and to a line shape different from the Lorentzian line shape. Our results are compared with numerical simulations. We show that the time evolution of an unstable state satisfies a Boltzmann-like $\mathcal{H}$ theorem. This is applied to emission and absorption as well as scattering. The existence of a microscopic $\mathcal{H}$ theorem is not astonishing. The excited states are ``nonequilibrium'' states and their time evolution leads to the emission of photons, which distributes the energy of the unstable state among the field modes.

Method For Making a Chlorhydrine by Reaction Between a Polyhydroxylated Aliphatic Hydrocarbon and a Chlorinating Agent

Abstract: The invention concerns a method for making a chlorhydrine from a polyhydroxylated aliphatic hydrocarbon, a polyhydroxylated aliphatic hydrocarbon ester, or a mixture thereof, and a chlorinating agent, the chlorinating agent containing at least one of the following compounds: nitrogen, oxygen, hydrogen, chlorine, a hydrocarbon organic compound, a halogen organic compound, an oxygen-containing organic compound and a metal.

Process for stabilising particulate alkali metal percarbonate

Abstract: The invention relates to a process for stabilising particulate alkali metal percarbonate and especially sodium percarbonate by coating it with an aqueous solution of a boric acid and a solubilising amount of an alkali metal or ammonium salt, such as in particular sodium and/or potassium chloride and/or sulphate and thereafter drying. The presence of such a neutral salt enables a greater weight of coating agent based on boric acid to be applied to the percarbonate in a given volume of aqueous solution, compared with boric acid alone.

Herstellung von Fluorverbindungen

Abstract: Inorganic and organic compounds containing fluorine can, for example, be produced from corresponding compounds containing chlorine by exchanging chlorine and fluorine using fluorinating agents. It was found that monocylic or bicyclic compounds having at least two nitrogen atoms, at least one of said nitrogen atoms being incorporated into the ring system, can be used as a catalyst or fluorinating agent for chlorine-fluorine exchange reactions. As a result sulphurylchlorofluoride, sulphurylfluoride or carboxylic acid fluoride can be produced. It is also possible to achieve HF addition to C-C multiple bonds and chlorine-fluorine exchange with respect to carbon atoms. Mono or dichloromalonic acid esters can, for instance, be converted into difluoromalonic acid esters. Preparation is simplified by using suitable solvents in order to force the reaction mixtures into a 2-phase zone.