文摘
New molecular beam scattering experiments are reported for the ammonia鈥揾ydrogen system recording with unprecedented resolution 鈥済lory鈥?quantum interferences in the total cross sections. Direct comparison with the analogous water鈥揾ydrogen complex, investigated under the same experimental conditions, highlights relevant differences in the intermolecular interaction affecting the observables. Analysis of the electronic charge displacement accompanying formation of both complexes, calculated using very accurate ab initio methods, helps to rationalize the experimental findings and unveils the selective and crucial role of charge transfer in driving water interactions and formation of a weak hydrogen bond.