Photoionization studies of germanium and tin clusters in the energy region of 5.0–8.8 eV: Ionization potentials for Gen (n=2–57) and Snn (n=2–41)

Abstract

Photoionization thresholds for Gen (n⩽57) and Snn (n⩽41) are examined by laser photoionization with detection by reflectron time-of-flight mass spectrometry. Stimulated Raman anti-Stokes scattering of narrow bandwidth 193, 248, and 266 nm radiation is used to produce ionization light sources in the vacuum ultraviolet region (200–141 nm). A very similar size dependence of the ionization potentials (IPs) is found for germanium and tin clusters with fewer than 12 atoms, featuring a major maximum at n=10. The rather high IP of Ge10 compared with its neighbors is consistent with the results of a photodissociation study of Gen+. We also find a rapid decrease in the IPs for Gen between n=15 and 26, which is very similar to that for silicon clusters reported in our previous paper. On the other hand, the IPs of medium size Snn (n=15–41) clusters are found to decrease slowly without such a gap. The remarkable difference in the size dependence of the IPs for the Sin, Gen, and Snn clusters is discussed in relation to the existence of a structural transition in the medium-size Sin and Gen clusters.

Emission of charged particles from laser-induced germanium ecton, vacuum spark, and vacuum arc

“…This time interval was found to be significantly long, as expected for a single germanium ion, even when considering the voltage drop of the gate. It can be concluded that clusters with at least 8-10 atoms were primarily extracted to the anode, in agreement with the fact that these types of clusters are most likely to be formed by germanium [30,31]. In particular, massive ionized clusters can readily overcome the potential difference of the cathodic gap, which was measured to reach an equilibrium voltage of around 500 V, and escape the plasma through the aperture.…”

Electronic properties for small tin clusters Snn (n ≤ 20) from density functional theory and the convergence toward the solid state

“…Experimental values for ionization energies were extracted from ref. 49, the upper and lower bounds of the experimental ionization potentials are given in Figure 3, and those for electron affinities of negatively charged clusters were from ref. 48.…”

“…46 Measured photoionization and -emission spectra are reported in refs. [47][48][49]. Calculated dissociation energies, bond lengths, and harmonic frequencies of Si, Ge, and Sn dimers were compared with the experimental results in ref.…”

The SiSn Chemical Bond: An Integrated Thermochemical and Quantum Mechanical Study of the SiSn Diatomic Molecule and Small Si–Sn Clusters

“…The appearance energies (AEs) of the atomic and homonuclear species were determined by calibrating the energy scale with the well-established ionization energy of gaseous gold, [31] using the linear extrapolation method. [32] The values so obtained compare favorably with previous determinations (selected literature data are reported in parentheses), confirming that the observed ions were formed by primary ionization processes (values in eV): Si + , 8.1 AE 0.3 (8.149 [31] ); Sn + , 7.3 AE 0.4 (7.342 [31] ); Si 2 + , 7.8 AE 0.3 (7.4 AE 0.4, [33] 7.913 [34] ); Si 3 + , 8.2 AE 0.5 (8.0 [33] ); Si 4 + , 7.7 AE 0.5 (7.6 [33] ); Sn 2 + , 7.0 AE 0.4 (7.06-7.24, [35] 7.2 [36] ); Sn 3 + , 7.4 AE 0.5 (7.58-7.76 [35] , 6.8 [36] ). The AEs of the polyatomic heteronuclear species have been determined to be as follows: Si 2 Sn + , 8.1 AE 0.7; SiSn 2 + , 7.2 AE 0.7; SiSn 3 + , 7.4 AE 0.7.…”