Electric Deflection of Middle-Size Ammonia Clusters Containing (e^–, Na⁺) Pairs

Abstract

Effective polarizabilities of Na(NH3)n (n = 8-27) clusters were measured by electric deflection as a function of the particle size. A significant field-induced shift of the beam intensity profile without the occurrence of broadening revealed that the clusters behave as liquidlike polar objects in the conditions of the experiment (cluster temperatures were estimated in the range of 110-145 K). Most of the cluster polarity is attributed to the spontaneous promotion of the alkali atom valence electron to a diffuse state stabilized by the cluster solvent field, with the consequent formation of (e(-), Na(+)) pairs. The average modulus of the dipole of Na-NH3 clusters, μ0, was determined using the Langevin-Debye theory, and the data was compared with previous measurements obtained for Na-H2O clusters. Sodium-doped ammonia clusters exhibit much larger μ0 values and a step size dependence which is not present when the solvent is water. This evidence suggests that while the (e(-), Na(+)) structure is rather compact in Na(H2O)n clusters and remains almost unchanged during the solvation process, in Na(NH3)n the unpaired electron abandons the proximity of the Na(+) ion and gradually extends and occupies new solvent shells.

Magnetic deflection of neutral sodium-doped ammonia clusters

“…Considering the level of theory and experimental uncertainties, this is consistent with experimental results with values for the fundamental wavenumbers ranging from 195 cm À1 to 215 cm À1 for the stretching and 278 cm À1 for the bending fundamental. 66,67 At estimated cluster temperatures in the range of 110-145 K, 21 excited states of these lowfrequency vibrations (vibrational temperature B300 K) are barely populated. This situation changes drastically for the larger clusters Na(NH 3 ) nZ2 .…”

“…Effective polarizabilities of Na(NH 3 ) n were determined from electric deflection studies. 21 Yet, detailed knowledge of the magnetic properties of the solvated electron in free clusters is still not established. To the best of our knowledge, we present the first study on the magnetic properties of small (n = 1-4) sodium doped ammonia clusters Na(NH 3 ) n investigated via Stern-Gerlach deflection.…”

Infrared spectroscopy of Ca(NH3) complexes

“…In the case of alkali metals, the earliest experimental studies of M(NH)n complexes employed photoionization mass spectrometry, and in particular the measurement of ionization energies as a function of n. [3][4][5][6][7] Unfortunately mass spectrometry provides limited structural information and so more recent work has exploited optical spectroscopy, including resonanceenhanced multiphoton ionization spectroscopy and photodepletion spectroscopy. [9][10][11][12][13][14] Other experimental techniques, such as photoelectron spectroscopy 15 and electric deflection measurements, 16 alongside various theoretical studies, [17][18][19][20][21] have provided a considerably detailed picture of the solvation of alkali atoms by ammonia molecules.…”

Joint electric and magnetic beam deflection experiments and quantum chemical studies of MSn12clusters (M = Al, Ga, In): on the interplay of geometric structure and magnetic properties in nanoalloys

“…Electric and magnetic beam deection experiments are well established tools to investigate the Stark and Zeeman effects of isolated atoms and clusters. [1][2][3][4][5][6] In this way, the dielectric and magnetic susceptibilities can be determined, in order to systematically study the inuence of size, 7,8 geometry [9][10][11] and chemical composition [12][13][14] on the dielectric and magnetic behavior of nanoalloy clusters.…”