Probing the dynamics of polyatomic multichannel elementary reactions by crossed molecular beam experiments with soft electron-ionization mass spectrometric detection

摘要: In this Perspective we highlight developments in the field of chemical reaction dynamics. Focus is on advances recently made investigation dynamics elementary multichannel radical–molecule and radical–radical reactions, as they have become possible using an improved crossed molecular beam scattering apparatus with universal electron-ionization mass spectrometric detection time-of-flight analysis. These improvements consist implementation (a) soft ionization by tunable low-energy electrons which has permitted us to reduce interfering signals originating from dissociative processes, usually representing a major complication, (b) different crossing-angle set-ups extend range collision energies over can be studied, very low (a few kJ mol−1, interest astrochemistry or planetary atmospheric chemistry) quite high (several tens temperature combustion systems), (c) continuous supersonic sources for producing wide variety atomic radical reactant beams. Exploiting these new features it tackle polyatomic such those occurring many environments ranging plasmas terrestrial/planetary atmospheres interstellar clouds. By measuring product angular velocity distributions, after having suppressed mitigated, when needed, problem species (reactants, products, background gases) detection, essentially all primary products identified, each channel characterized, branching ratios determined function energy. general information, besides being fundamental relevance, required predictive description chemistry via computer models. Examples are taken recent on-going work (partly published) reactions oxygen acetylene, ethylene allyl radical, great importance combustion. A relevance chemistry, that carbon also discussed briefly. Comparison theoretical results wherever possible, both at level electronic structure calculations potential energy surfaces dynamical computations. Recent complementary CMB well kinetic exploiting photo-ionization synchrotron radiation noted. The examples illustrated article demonstrate type now obtainable might complement kinetics experiments hence contribute bridging gap between microscopic thermal kinetics, enhancing significantly our basic knowledge reactivity understanding occur real-world environments.