Velocity selection and mass spectrometric detection of an H2S molecular beam and a collisional study of its interactions with rare gases

A molecular beam scattering study of the weakly bound complexes of water and hydrogen sulphide with the main components of air

“…According to the ILJ model, the functional form of the interaction potential V(r) is the following where The ε parameter defines the potential well depth; r m fixes the equilibrium distance and β depends on the hardness of the involved chemical species, determining the potential shape in the well region [34]. For the present systems we have used for all the cases β=9, a typical value for non-covalent interactions [8,26,32,34].…”

“…As for other cases previously studied [8,[24][25][26][27][28], such an approach is useful to identify the intermolecular potential components that may add to the ubiquitous van der Waals interaction. For example, we recently reported [27,28] integration of the change in electron density occurring upon the formation of rare gaswater complexes (computed with accurate ab initio methods and basis sets), we mapped the local charge displacement along the whole intermolecular region and were thus able to appraise CT effects free of the inherent ambiguity of charge decomposition models [27,28].…”

Polar molecules engaged in pendular states captured by molecular-beam scattering experiments

“…Although this choice provides a loss of velocity resolution because of the increased random motion of the target, it avoids condensation effects on the chamber walls and maintains the rotational distribution of the target molecules in the room temperature range. As previously [42,47,48], the absolute values of Q(v) have been obtained by an internal calibration of the NL factor, based on the direct measurement of the gas flow in the scattering chamber [49] and on the absolute values of the He-Ar cross section [50][51][52]. As stressed before, MBs used in the present investigation contain rotationally hot molecules showing an average rotational period comparable or shorter than the typical collision time [42,46,47,53].…”

“…Under these conditions only single-pair collisions occur, molecules show rotations and relative collision velocities confined in the thermal energy range, and inelastic effects promoting the quenching of interference patterns are significantly reduced, the elastic events being dominant [54]. Previous measurements of Q(v) for water, ammonia, and hydrogen sulfide molecules interacting with noble gas atoms or simple apolar molecules [41,42,47,48,55,56] provided wellresolved quantum interference oscillations. The analysis of their amplitude and frequency, achieved by the use of a radial interaction potential, led to an accurate characterization of the absolute scale of V (r), whose long-range attraction has been directly obtained from the measuredQ(v).…”

Rovibrational energies and spectroscopic constants for H2O−Ng complexes

“…The Improved Lennard-Jones model (ILJ) [32], found to be suitable to formulate V (R) for several systems of different nature and at increasing complexity [31,32,[35][36][37][38], stands out as an interesting model that eliminates most of the original LJ model inadequacies, particularly those from short and long range. This is accomplished in an elegant fashion through the consideration of a single extra parameter.…”