Experimental studies of cluster ions containing water, ammonia, pyridine and bisulphate

摘要: Molecular cluster ions are fascinating subjects of study. Bridging the size gap between molecules and bulk, they often display non-trivial dependent behaviour properties. As an example, for some types there certain sizes that found in unusually high abundance a produced distribution, these referred to as “magic numbers”. Apart from being interesting their own right serving useful model systems number applications, molecular clusters have very real important role vast dynamic system we refer atmosphere. act precursors formation atmospheric particles. such, it is necessary learn much possible about formation, growth, physical properties chemistry clusters, because particles form will ultimately large effect on global climate. This work investigates ionic gas phase reactions with heavy water ammonia, also effects collision induced dissociation air. done beam experiments, using two different experimental setups. The first instrument quadrupole-time-of-flight instrument, consisting electrospray ion source, quadrupole mass filter, cell time-of-flight spectrometer. In this relative reaction cross sections were measured H(H2O)n, H(NH3)1(H2O)n H(pyridine)1–3(H2O)n colliding D2O; H(pyridine)1–2(H2O)n H(NH3)1(pyridine)1(H2O)n NH3. results H(pyridine)1(H2O)n + NH3 used improve kinetic positive composition. Abundance spectra evaporation patterns recorded all clusters. It was protonated containing pyridine do not magic numbers investigated range (≤ 1500 u), unlike water, ammonia. Furthermore same those H(NH3)1(H2O)n. Cluster D2O proceed through short-lived complex. add molecule subsequently lose D2O, HDO or H2O molecule; latter channels associated increase one atomic units, respectively. species requires proton mobility, known occur H(H2O)n channel leading observed ammonia molecule, which attributed bound place by Bronsted base. However, experiments indicate mobility three molecules, H(pyridine)2–3(H2O)n. Quantum chemical calculations suggest may be due transfer forming H3O, along wire hydrogen bonds. second double sector having magnetic sector, electrostatic sector. Collision H(NH3)m(H2O)n (m = 4–6) six prefer NH3, while four five H2O.